ML20247F971
| ML20247F971 | |
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| Site: | FitzPatrick  |
| Issue date: | 04/30/1994 |
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| EP-91-28, NUDOCS 9805200103 | |
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Text
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EASTERN LAKE ONTARIO RESEARCH ON-SHORE FLOW FIELD STUDY REPORT EP 91-28 PREPARED BY:
FINAL REPORT GALSON CORPORATION APRIL 1994 5.
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4 EASTERN LAKE ONTARIO RESEARCH ON-SHORE FLOW FIELD STUDY REPORT EP 91-28 PREPARED BY:
FINAL REPORT GALSON CORPORATION APRIL 1994
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EMPIRE STATE ELECTRIC ENERGY RESEARCH CORPORATION 9805200103 990226 PDR ADOCK 0500 3
1 Members of the Empire. State Electric Energy Research Corporation I
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CENTRAL HUDSON GAS &. ELECTRIC CORPORATION CONSOLIDATED EDISON COMPANY OF NEW YORK, INC.
LONG ISLAND LIGHTING COMPANY f;
NEW YORK POWER AUTHORITY i
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NEW YORK STATE ELECTRIC & GAS CORPORATION i
' NIAGARA MOHAWK POWER CORPORATION ORANGE AND ROCKLAND UTILITIES, INC.
ROCHC_ STER GAS AND ELECTRIC CORPORATION I
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Final Project Report ESEERCO Project EP 9128 Eastern Lake Ontario On-shore Flow Field Study NEW YORK POWER AUTHORITY April 1994 DOCUMENT REVIEW STATUS Prepared by:
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1 Cf ACCEmo Galson Corporation 2 0 ACCEND AS NOTED RESUBMfTTAL NOT RLIQUIRED 6601 Kirkville Road a
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ACCEND AS NOTED East Syracuse, New York 13057 RESUSMfTTAL REQl.HRED 4 O NOT ACCEND Principal Investigator
! p.menon o peceed ens not consam sampience w approval or mWon
! mass,cowsmas,ano es,wmandsamammnewedasesed r
i n, = senw and mes not maa supow hom u compunce we Christopher D. Bedford, CCM i coinewnsoppons;,, p, o '
' REVIEWED BY..
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anal Subcontracted Effon Supplied by:
DAT E:.....*2.I. d AWS Scientific, Inc Radian Corporation 3 Washington Square P.O. Box 201088 Albany, New York 12205 Austin, Texas 78720-1088 Principal Investigation Mike Marcus Principal Investigation Gary Zeigler The Research Foundation of the State Sonoma Technology, Inc.
I University of New York 5510 Skylane Boulevard.
SUNY - Brockport Suite 101 Brockport, New York 14420 Santa Rosa. California 95403 Principal Investigation Dr. Greg Byrd P6cip) Investigation Timothy Dye The Research Foundation of the State Sigma Research Corporation University of New York 196 Baker Ave SUNY - Oswego Concord, Massachusetts 01742 Oswego, New York 13126 Principal Investigation Dr. Lloyd Schulman
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Principal Investigator Dr. Robert Ballentine l
Prepan:d fon Empire State Electric Energy Research Corporation 1515 Broadway New York, New York 10036 Niagara Mohawk Power Corporation 300 Eric Boulevard, West -
Syracuse, NY 13202 j
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Copyright 01994 EMPIRE STATE ELECTRIC ENERGY RESEARCil CORPORATION. All rights reserved.
i LEGAL NOTICE i
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'Ihis repon was prepared as an account of work sponsored by the Empim State I
Electric Energy Research Corporation ("ESEERCO"). Neither ESEERCO, members of ESEERCO nor any person acting on behalf of either;
- a. Makes any warmnty or representation, express or implied with respect to die accuracy, completeness, or usefulness of the information contained in this repon, or diat ute 4
use of any infom1ation, appantus, method, or pmcess disclosed in this repon may not infringe.
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privately owned rights; or
- b. Assumes any liability with respect to the use of, or damages resulting from the use J
of, andy infonnation, apparatus, method or process disclosed in this repon.
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A bstract ne Eastem Lake Ontario On-Short Flow Field Study was designed to address several nuclear-specific meteorological issues in the coastal zone near Lake Ontario. Specifically, the following issues were investigated: Location and height of elevated stability layers; stability classification problems; vertical variation of wind speed; data bases for model validation studies; and suitability of new remote sensing technerogy. These issues wee studied through one-year of continuous site-specific metecmlogicd monitoring using reousdc sounders, meteorological towers, a microwave profiler, and a Radio Acoustic Sounding System (RASS). Continuous monitoring data was supplemented with intensive observatens to collect detailed infomiation during targeted meteorological conditions.
Acoustic sounders were esed to observe the occurrence of elevated mixed layers and stability gradients. The monitoring failed to identify a statistically significant number of thennal intemal boundary layers (TIBL). It is recommended that TIBL heights be estimated using robust empirical expressions. No justification for relocating the tall meteorological tower was determined. The cunent tall tower should be used to estimate release height winds. A 10 m tower located inland should be used to provide TIBL stability. Pennanent installation of an acoustic sounder is also recommended.
A micrometeorological tower was installed and opemted for a one-year period to measure stabi!ity using several techt.tes and investigate stability classification problems in near-shore areas. he results show thu L.:al conditions must be factored into determining the most appropriate stability class for dispersion modeling. In cases involving complex meteorology (i.e. coastal zones), consideration
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should be given to the collection of stability data at heights close to release elevation.
De vertical variation of wind speed was investigated by obtaining wind speed measurements at potential release elevations using a tethersonde and concunent measurements frt,m the 200 ft meteorological iower. He results indicated difficulty in estimating instantaneous wind speed at release elevations using established empirical expressions. Continuous measurements at release elevations are recommended for emergency response applications along with refined profile exponents for avemge winds used in routine release imprt assessments.
Detailed measurements of meteorological regimes were collected in onier to develop detailed data for the development and validation of cumerical models for predicting the transport and dispersion of pollutants in shoreline environments.This data, combined with the other measurements taken during this study should provide researchers with a data set suitable for developing and validating conceptual and numerical models of the dispersion meteorology along the southern shore of Lake Ontario.
1 A 915 MHz Profiler and RASS were operated for a period of one year to evaluate the technology as a l
possible replacement for existing tall meteorological towers at nuclear facilities. It was concluded that the new technology is not a replacement for tall towers but can provide irnpon mt supplemental information. Combined wi'h an existing 200 ft meteorological tower and sodar for profiling in the lowest portion of the boundary layer, the profiler and RASS can provide valuable information on plume level wind and temperature stmeture.
This study focussed on the unique meteorological pmblems fred by power generating frilities located in coastal environments. De infonnation and findings are applicable to facilities which must f
make esumates of the downwind dispersion of air pollutants in a coastal environment.
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Acknowledgements L
Galson Corporation wishes to xknowledge specifically the following Galson Employees for their -
'significant contributions to the data collection, data analysis and repon production associated with dds project:
- Christopher Bedford CCM - Senior Project Manager
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R. Leland Davis, CCM - Senior Consultant Mark Distler - Technical Suppon John Ferlito - Technician Robert Heman - Technician Scott Manchester i Technician Christopher Weigelt - Site Operator
- Additional acknowledgements and thanks are extended to the Subcontractors and their Project Managers:
AWS Scientific, Inc. (Mike Marcus)
Consultant (Dr. Roben Ballentine)
Radian Corporation (Gary Zeigler)
Sigma Research Corporation (Dr. Lloyd Schulman, CCM)
State University of New York State at Brockpon (Dr. Greg Byrd)
State University of New York State at Oswego (Dr. Len Ke',hishian)
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The following individuals also made significant contributions to the completion of this project:
Andrew Korik, CCM - Environmental Products and Services, Inc. (formerly of Galson Corp.)
Gar Lala-AWS Scientific,Inc.
John Neuschaefer - Radian Corporation David Vaello - Radian Corpration S' ave Weinbeck - SUNY-Brockpon Rich Woolley E.A. Science and Technology The most significant thanks go to the following ESEERCO representatives for their suppon, direction,
. and patience:
.Mr. Tom Galletta - Project Manger (NMPC),
James Burger. Program Manager (ESEERCO)
Roger Caiazza, CCM - Technical Consultant (NMPC) iii
a Table of Contents VOLUME I-FINAL REPORT Legal Nodce.....................................
..........................1 A bstme t.........................................
.........................11
- Acknowledgements........................................
...... 111 Table of Contents....................................
....................... iv.
- List of Figures.................................................
............ix List of Tables.........................................
......................x Executive Summary....................................
.....................xi In trodu ction......................................
.........................1 Secdon 1.0 Monitor Coastal Transition Zone latemal Boundary Layer.......
1-1 1.1 B ackground..................................
............1-1 1.1.1 Meteorology of the Coastal Transition Zone...
1.1.2 Applicadons to Nuclear Facilities.........................
1 - 1
............15 1.2 S tudy Objective.................... -..............
..........1-6 1.2.1 S tudy Goal.............................
' 1.2.2 Potential Applicadons for Research........................
1 - 6
............1-7 13 Appro ac h.................................
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............1-7
'13.1 Descripdon of the Monitoring Instrumentation..............
13.2 Sampling Approach........
1-8 133 Data Analysis.......................................
1 - 9 133.1 Detennination of Elevated Mixin.......................
133.2 Identification of TIBLS.......g Layers.............
1 - 11 1 - 12 l
....................1-13 1.4 Data Analysis Results......................
1 - 15 1.4.1 Multiple Mixing Layer Analysis......
1.4.2 TIBL Height Analysis..............................
1 - 15 1 - 1 6 1.5 Conclusions and Recommendations..................
Y' 1 - 18 L
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1 1.6 References........
1 - 20 i Section 2.0 ' ' Evaluation of Stability Classification Schemes 2.1 B ac kground '..................
. 2 -' l
. Stability Classification Schemes........................ '2 L 2.1.1 2.1.2.. Applications to Nuclear Facilities..
~2-3'
~ 2.2 Study Objective....
2 - 4 2.2.1
'S tudy G oal :.................................
........2-4 2.2.2 Potential Applications for Researth...............
2-4.
2.3 A ppro ac h................................................ 2 4 2.3.1 Description of Monitoring System........................ 2 - 5
- 2.3.2 Sampling Technique and Data Validation..........:......... 2-5 2.3.3 Dat a Anal ysi s ~......................................... '2 - 6 2.3.3.1 Objective Technique............................. = 2 - 6 2.3.3.2 Sigm a-theta.................................. 2 - 6 2.3.3.3. Delta-temperature............................... ' 2 '- 7
. 2.3.3.4 Solar Radiation / Delta-Temperature
..................'2-8' 2.3.3.5 Net Radiation and Wind. Speed..................... 2 - 8 2.3.3.6 Solar Radiation and Wind Speed (Day)/ Net Radiation and Wind
. Speed (Night)................................. 2 - 9 2.3.3.71 Richardson's and Bulk Richardson's Numbers.......... 2 2.3.4 Data Analysis ~.....................................
2 -- 1 1
. 2.4 Data Analysis Results.....................................
2.-l 1 1
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. 2.5 Conclusions and Recommendations............................
2 - 13
. '2.6 Re fere nces -.............................................
2 '- 16 LL Section 3.0; " Monitor Vertical Wind Profile.................................... 3 - 1 1
f 3.1 B ac kg ro u nd............................................. 3 ;..
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3.1.1 Vertical Wind Profile Estimates......................... 3 2 3.1.2 Applications to Nuclear Facilities........................ 3 - 4 '
3.2 Study Objective........................................... 3 - 4 3.2.1 S tudy Go'11........................................ 3 5 3.2.2 Potential Applications for Research........................ 3 5 V
3.3 Appro ac h................................................ 3 5
- 3.3.1.
Descripdon ' f Monitoring System............
o Sam pling Technique................................. 3 3.3.2 Data Analysis..................................... 3 - 6 z 3.3.3 '
.s Limitations of Study.................................. 3 3.3.4
..... 3-8
< 3.4 Data Analysis Results...................................... 3 - 9 3.'.1
, Summary of Test Conditions..........................
3 - 10 4
3.4.1.1 Test 1 - June 23,1992.........................
3 - 10 3.4.1.2 Test 2 - August 6, 1992.......................... 3 - 10 3.4.1.3 Test 3 - August 24,1992.......................
3;11 3.4.1.4 Test 4 - September 13, 1992.....................
3 - 1 1 3.4.1.5. Test 5 - October 5, 1992.......................
3 - 1 1 3.4.1.6 Test 6 - October 6, 1992.......................
3 - ~ 12 -
3.4.1.7 Test 7 - October 7,1992...............
3 3.4.1.8 Test 8 - May 10,1993..........................
3 3 12 3.4.2. Analysis of the 200 ft Benchmark Data..................... 3 - 13 3.4.3 Observed Wind Profile Exponents '......................
3 - 13 3.4.4
. Observed Wind Profiles Compared to Predicted.............. ' 3 - 15..
3.5 Conclusions and Recommendations............................
3 - 15
' 3.6 Re fere nces............................................. 3 - 17..
Section 4.0 Detailed Regime Measurements................................... 4 - 1.
I' 4.1 B ackgrou nd.......................................... 4 1 4.1.1-Imponant Meteorological Regimes Over Eastem Lake Ontario, 4 - 2 i
4.1.1.I' On-shore Flow
. 4-2 4.1.1.2 Lake B reeze.............................. 4 - 3 4.1.1.3 Land Breeze
..............................4-4 4.1.1.4 Low Level Jet (Noctumal Wind Maximum)........ 4 - 4 4.1.2 Applications to Nuclear Facilities..................... 4 - 5 I
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4-5 4.2 Study Objecdve 4-6 4.2.1 Study Goal...
4-6 4.2.2 Potendal Applications for Research 4-7 4.3 Approrh...
..... 4-7 4.3.1 Descripdon of Monitoring Systems...
.. 4-7 4.3.1.1 Meteorological Tower....
..... 4-7 4.3.1.2 Tethersonde.......
.. 4-8 4.3.1.3 Radiosonde.............
4.3.1.4 Monostade Acoustic Sounder..............
.. 4-9
. 4 - 10 4.3.1.5 Doppler Acousde Sounder.........
. 4 - 11 4.3.1.6 Microwave Profiler....................
4.3.1 J R ASS.........
........................4-11
. 4 - 12 4.3.2 Sampling Technique..
4.3.2.1 Subtask 1 - Simultaneous Soundings at Ginna and NMP4 - 12 4.3.2.2 Subtask 2 - Detailed Lake-induced Regime Case Studies 4 - 12 4.3.3 Data Analysis..
...........................4-14
.... 4 - 14 4.4 Data Summary..............
. 4 - 14 4.4.1 IOP Event Summaries........................
4.4.1.1 IOP Number 1 - May 20 to 22,1992 (On-shore Flow and Lake Breeze........
................. 4 - 14 4.4.1.2 IOP Number 2 - June 22 to 23,1992 (Land Breeze and Low Level Jet)............................... 4 - 16 4.4.1.3 IOP Number 3 - August 5 to 7,1992 (Ginna Comparison.
On-shore Flow and Lake Breeze)............... 4 - 16 4.4.1.4 IOP Number 4 - August 21 to 23,1992 (On-shore Flow and
... 4 - 18 Lake B re eze)...........................
4.4.1.5 IOP Number 5 - September 12 to 13 (Land Breeze, LU, Lake B re eze).................................. 4 - 19 4.4.2 Digital Data Files................................ 4 - 21 i
4.5 Conclusions and Recommendations......................... 4 - 21 vii I
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i Section 5.0 Evaluation of Wind and Temperatum Remote Sensing Technology......... 5 - 1 5.1 B ac kground.............................................. ~ 5 - 1 y
5.1.1 > Tower-based Instmmentation............................ 5 ' 2 5.1.2. Balloon-bome instmmentation......................... 5-2
' 5.1.3 ". Atmospheric Remote Sensing Instrumentation...............L5-3 5.1.3.1'. Acou'stic Sounders and Sodar..................... 5 - 3
' 5.1.3.2 Radar Wind Profiler............................ 5 - 4 '
5.1.3.3 Radio Acoustic Sounding System.................. 5 - 5 5.1.4 Applications to Nuclear Facilities......................... l 5 - 6 5.2 Study Objective............................................ 5 - 7 5.2.1 S tudy Goal......................................... 5 - 7 5.2.2 Potential Applications................................ 5 - 8
- 5.2.3. Limitations of Study...........,..................... 5 - 8 i
- 5.3 Field Monitoring Summaiy.................................. 5 - 9 5.4 Summary of Radar Profiler and RASS Evaluation.... -.............. 5 -12 j
f 5.5 Conclusions and Recommendations............................. 5 - 14 1
5.6 Refem nces...... :,..................................... 5 - 161 e
i VOLUME II APPENDICES
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_ Appendix 'A
- Stability Fmquency Distribution Tables--
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fAppendix B Wind Profile Data Summary i
Appendix C IOP Summary Data f.p Appendix D-1 Final Report to Galson Corporation: " Evaluation of the Perfonnance of. 915 MHz c
L Profiler During the Eastem Lake Ontario Onshom Flow Study
. ' ppendix D-2 Supplemental Report to Galson Corporation: "Results of Re-siting Experiment of the f
A 915 MHz Radar Wind Profiler at the Nine Mile Point Nuclear Power Generating Facility" t
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List of Figures Figure 1-1 Schematic of Wind Profile Modification in an Aerodynamic Intemal Boundary
,, 1 - 21 Layer -
Figum 1-2 Schematic of Temperatum Prufile Modification in a Thennal Intemal Boundary 1 - 22 Layer..........
Figum 1-3 Vertical Velocity Obtained by an Aircraft Flying through the TIBL (left) iuto Stable 1 - 23 Marine Air (Right)
Figum 1-4 TIBL Height vs Distance Inland Using Robust Formula (Hanna,1991)....
1 - 24 Figum 15 '
Field Monitoring Ama - Eastem Lake Ontario On-shore Flow Field Study...
1 - 25 Figure 1-6 Frequency of Multiple Mixing Heights at NMP by Month - November 1991 thmugh October 1992.....
......................................1-26 Figure 1-7 Frequency of Multiple Mixing Heights at NMP by Hour - November 1991 through October 1992.............................
................1-27 Figure 1-8 Estimated TIBL Height versus Distance from Shore: MAR-5-1992.......
1 - 28 Figure 1-9 Estimated TIBL Height versus Distance from Shore: APR 10-1992........
1 - 29 Figum 1-10 Estimated TIBL lleight versus Distance from Shore: MAY-6-1992...
1 - 30 Figum I-11 Estimated TIBL licight versus Distance form Shore: MAY-14-1992......
1 - 31 Figure 1-12 Estimated TIBL Height versus Distance from Shore: MAY-15-1992.......
1 - 32 Figure 2-1 Micrometeorological Tower Installation Schematic................... 2 - 17 Figure 31 Plots of Differences in Estimating the Wind Profile (using two different methodsE - 18 Figum 3-2 Schematic of the Tethersonde Boundary Layer Profiling System and Attached Instru ment Pac kage.......................................... 3 19 Figure 3-3 9MP vs Tethersonde 200 ft Wind Speed........................... 3 - 20 Figure 3-4 9MP 350 ft Predicted vs Tethersonde Observed 350 ft Wind Speed........
3 - 21 Figum 3-5 9MP 385 ft Predicted vs Tethersonde Observed 385 ft Wind Speed.........
3 '- 22 Figure 3-6 9MP 430 ft Predicted vs Tethersonde Observed 430 ft Wind Speed......... 3 -23 l
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List of Tables Table l-1 Percent Data Capture - Monostatic Sounders...
. 1 - 33 Table 12 Time Periods investigated for Potential TIBL Identification............
1 - 34 Table 1-3 Frequency (%) of Multiple Mixing Layers November 1991 through October 1992............................
1 - 3 5 Table 1-4 Observed Temperature, Precipitation and Sunshine Conditions Syracuse, NY 199 2.........................................
1 - 3 6 Table 2-1 Percent Data Capture - Micrometeorological Tower, All Hours October 1991 through September 1992....................
...... 2 - 18 Table 2-2 Summary of the Objective Stability Classification Scheme.............. 2 - 19 (used as the baseline for comparison to altemative schemes Table 2-3 Stability Classification Criteria Based on the Sigma-theta Method......... 2 - 20 Table 2-4 Delta Temperature Criteria..................................... 2 - 21 Table 2-5 Solar Radiation (DayySigma-theta (Night) Stability Classification Method... 2 - 22 Table 2-6 Daytime Williamson and Krenmayer Wind Speed Cormeted Net Radiation.. 2 - 23 Table 2-7 Williamson and K enmayer Wind Speed Correction Solar Radiation (DayyNet Rad iation (Night)............................................ 2 - 24 Table 2-8 Jo!r.t Frequency Table (Percent) of Objectively Detennined Stability Class versus the Delta-Temperature Method for the 2-10 Meter Tower.................. ' 2 - 25 Table 2-9 Joint Facquency Table (Percent) of Objectively Determined Stability Class versus the Sema-Theta Method for the 2-10 Meter Tower..................... 2 - 25 Table 2-10 Joint Frequency Table (Percent) of Objectively Determined Stability Class versus the Solar Radiation (davVDelta-Temnemtum (nicht) Method for the 2-10 Meter Towd
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Table 2-11 Joint Frequency Table (Percent) of Objectively Determined Stability Class versus the 3
Net-Radiation Method for the 2-10 Meter Tower..................,.. 2 - 26
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Table 2-12 Joint Frequency Table (Percent) of Objectively Detemnined Stability Class versus the W
Solar Radiation (davVNet Radiation (nicht) Method for the 2-10 Meter Tower. 2 - 26 J
Table 2-13 Joint Frequency Table (Percent) of Objectively Determined Stability Class versus the Richanison's Number Method for the 2-10 Meter Tower................ 2 - 26 Table 2-14 Joint Frequency Table (Percent) of Objectively Detemnined Stability Class versus the L
Sicma-Theta Method for 9MP at the 30 ft Level......
.............2-27 Table 2-15 Joint Frequency Table (Percent) of Objectively Determined Stability Class versus the y
Sicma-Theta Method for 9MP at the 30 ft Level.................... 2 - 27 Table 2-16 Joint Frequency Table (Percent) of Objectively Determined Stability Class versus the Sicma-Theta Method for 9MP at the 100 ft Level..................
2 - 27 Table 2-17 Joint Frequency Table (Perrent) of Objectively Determined Stability Class versus the
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Sicma-Theta Meth_od for 9MP at the 200 ft Level.................... 2 - 28 Table 2-18 Joint Frequency Table (Percent) of Objectively Determined Stability Class versus the Delta-Temocrature Method for 9MP between the 30 ft and 100 ft Level.... 2 - 28 Table 219 Joint Frequency Table (Pertent) of Objectively Determined Stability Class versus the Delta-Temperature Method for 9MP Between the 30 ft and 200 ft Level.
2 - 28 l
Table 31 Established Power Law P-factor Values,..
3 - 24 Table 3 2 Summary of Field Monitoring Data 3 - 25 Table 3-3 Summary of Measured Differences Between 9MP and Tethersonde 200 ft Elevati0n 26 Table 3-5 Summary of Calculated Power Law Coefficients (P) for 385 ft.......... 3 - 27 Table 4-1 IOP Monitoring Data Summary 4 - 23 x
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l l-EXECUTIVE
SUMMARY
The Eastern Lake Ontario On-Shore Flow Field Study (ELOOFFS) was designed to study unique meteorological conditions near the southeaster shore of Lake Ontario. The primary objective of the study was to collect meteorological data within 10 lan of the coastal transition zone in order to characterize meteorological parameters related to the tmnsport and diffusion from power genemting fxilities during on-shore flow conditions.-
In compliance with Federal Regulations regstding emergency planning, nuclear power generating facilities in the Urdted States are required to have " adequate methods, systems, and equipment for assessing and monitoring of the actual or potential offsite consequences of a radiological emergency condidon " In order to meet the meteorological aspects of this regulation, nuclear power generators must have the capability of making near real-time predictions of the transport and diffusion of effluent from their facilities. In order to make such predictions, meteorological data capable of describing the state of the atmosphere is vital.
~ Ihe ESEERCO sponsored Eastem Lake Ontario Meteorological Study (ELOMS) was recently I
' conducted to investigate mesoscale (ie. from 2 to 200 km) complexities in the vicinity of the lake Nuclear fxilities are concemed with conditions over even shorter distances (0 to 80 was designed to enhance the ELOMS results by addressing several nuclear-specific issues over sho distances. Specifically, this study investigated the following problems and issues:
Location and height of elevated stability layers Stability classification problems e
Venical variation of wind speed e
Data bases for ELOMS and related model validation studies Suitability of new ' remote sensing technology Five specific objectives wue identified in onler to target the research of this project:
I. Determine the most appropriate location for a meteorological tower to satisfy Nuclear Regulatory
,i Commission (NRC) guidance through measurements of the height of the thermal intemal bounda; layer (TIBL). Knowledge of the T1BL height assists in better assessing the stability of air into which specific plumes are released.
I II. Address problems related to stability classification using shoreline meteorological towers. Funhe investigation leads to recommendations on what methods should be used for assessing stabil
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111. Measure winds at release and plume heights and compare with other, standard measurement elevations. Determine if empirical expressions provide reliable, instantaneous wind speed estimates at different elevations.
IV. Make observations at Nine Mile Point (NMP) Nuclear Station and Ginna Nuc to detemiine the comparability of results and collect detailed data in suppon of validation studies for the ongoing mesoscale meteorological modeling ponion of the Eastem Lake Ontario j
Meteorological Study.
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Evaluate the potential of next generation atmospheric profiling technology using a Microwave l
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wind profiler and radio acoustic sounding system as an attemative to tall meteorological towers and Doppler Acoustic Sounders (SODAR) for measuring wind and temperature parameters in thei boundary layer.
Rese objectives were addressed thmugh one-year of continuous site-specific meteorological monitoring using monostatic acoustic sounders, meteomlogical towers, a microwave profiler, and Radio Acoustic Sounding System. Continuous monitoring data was supplemented with short-term, j
l intensive observations with field teans collecting detailed infomiation during targeted meteorological f
conditions using tethered and free-flying instmmentation (Tethersondes and Radiosondes).
He following summarizes the approach, conclusions and recommendations for each of the objecdves identified above:
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In order to obtain data regarding the variation of the boundary layer with inland Objective I:
distance from shore, three monostatic acoustic sounders were placed a locations f
pmgressively inland. The acoustic sounder is capable of identifying elevated mfxed layers by sensing acoustic backscatter characteristics of the atmosphere. Backscatter intensity is a function of thennal and velocity gradients. Inspection of the backscatter data allowed identification and interpretation of elevated mixing layers and related stability gradients.
f he one year of monitoring failed to identify a statistically significant number of I
TIBLs over Nine Mile Point. A few hours of intemal boundary layers were identified j
and showed reasonable agreement with the theoretical expressions for TIBL height as a function of inland distance. The limited data set was insufficient to develop or v'erify l
a site-specific TIBL height expression. Due to the limited TIBL data set, no justification can be made regarding the location of the meteorological tower. He I
sounder data did, however, clearly show evidence of more than one elevated mixing i
height approximately 25% of the time.
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Further analysis of the data is recommended. It is also recommended that the current practice of estimating TIBL height using robust empirical expressions such as thosei suggested during ELOMS, be continued. No justification for relocating the tall g-meteorological tower was detennined. He research suggests that the tall tower should j
be maintained at its current location in order to provide the best estimate of release height winds. In addition, a 10m tower located approximately I km inland is recommended in order to provide a measurement of the stability inside the TIBL.
4 Due to the apparent frequency of complex mixing layer pattems observed in the one-l.
year of sounder data, it is recommended that an acoustic sounder be made routinely available to operators at the facility in order to facilitate assessment of vertical stability l' variation on an operational basis.
iI To address problems atlated to the classification of atmospheric stability in the coastal
?
Objective II:
zone, a ify meter micmmeteorological tower was installed and operated for a one-year period.1:.itrumentation was installed to measure stability using seven commonly l
accepted techniques, and the stability classes determined from each technique 4
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il compared with those calculated using routine data from the NM tower.
The results showed that local conditions must be fact most appropriate stability class and, therefom, the selection of ap coefficients. In cases involving complex mercoro l
r clease elevation. Dispersion predictions for ground level releases shou l i l surface stebility classifications such as those obtained using the microm entative tower. Predictions for ele ~tted releases should e l
t NMP.
Specifically, for elevated releases, use of the f
flow. For near-surface thennal fluxes and mechanical effects and s the near-surfxe releases, use of the sigma-theta method from either th ")
30 ft level of the NMP tower are recommended. The sigma-theta include a site-specific surfre roughness correction.
The representativeness of empirical extrapolation of wind spee i
i d speed the highest measwed elevation was investigated by obtain ng w n Objective Ill:
filing me-surements at potential release elevations using a tethersonde l
system, and concurrent measurements fmm the existing 200 A comparison was conducted between the 200 ft measuremen elevations.
Based upon the limited data set collected during Ods study, the 5
d exponents employed to correct 200 ft wind speed to release f bi The 430 ft tend to over predict the xtual wind speed on an observation-s b
en application of a wind profile exponent becomes less reliable a f
scale the reference and predicted elevations increases. The occurrence o meso d
phenomena such as take breezes, land breezes, and noctum h
maximums are problematic for the application of wind profile expon large vertical variations in meteorological parameters observedI With respect to the current meteorological observing system, b
tion-wind speed provides a better estimate of release height wind spee nts specific basis than use of the power law. It is recommended t b
using a combination of tower, tethersonde and remote sensing instr performed on a regular basis (e.g. annually). Continuous m elevations are recommended by either employing a tall meteorologic id reliable remote sensing system, depending on the data recovery ob
~
Use of established wind speed profile exponents to detennine the elevations is most likely appropriate for routine release calculations.
profiles should be refined with xtual measmements betwe elevations.
l xiii j
l 4
1
.~
l Detailed measurements of specific meteorological regimes were collected in o develop a detailed data base for use in the development and validation Objective IV:
predicting the tmnsport and dispersion of pollutants from power gene located in shoreline environments. Difficulty in obtaining concurrent measurements Ginna and NMP in similar weather conditions made direct comparison betwee two sites impossible.
In general quality, high resolution data was obtained during weather con favomble for each of the targeted meteorological regimes. De data, combine I
other measurements taken during the Eastem Lake Ontario On-shore Flow as well as routine meteorological measurements in the area should pmvide with a data set suitable for developing and validating conceptual and numer of the dispersion meteorology along the southem shore of Lake Ontario.
Obtaining measurements of meteorological phenomena of concem to uti valuable and recommended as a suitable course of action to obtain detailed layer profiles whenever possible. Use of the monitoring data by res in the development and validadon of models over southem Lake Ontario s actively encoumged.
A 915 MHz Radar Profiler and Radio Acoustic Sounding System (RASS) wer operated for a period of one year in the vicinity of NMP. The purpose Objective V:
monitoring was to eva'uate the perfonnance of these new monitoring systems possible replacements for existing tall meteorological towers and data at levels well above that typically observed by the tall towers. The pr capable of providing supplemental information on wind direction an mnging from 400 to 12,000 ft above the surface, and the RASS can pm information between 400 and 500 ft..
Operational reliability of the systems was quite high during this st profiler system operated was a developmental version and not th version available. The system was available approximately 96 percent of t Data recovery, however, is dependent on operational status, weather, and conditions, This particular site suffered from ground clutter problems w data recovery. A data recover rate of 83 pertent was the best achieved.
A short test of the radar profiler at another location at the end of the moni program showed significantly improved data re the system since the antenna were not pointed over the lake where g would have been minimized.
Based upon this experience, the project team concluded that Ra are not a replrement for tall towers. They are, however, capable of s tower-based measurements with detailed observations between the the middle troposphere. Combined with the existing NMP 200 ft meteo and sodar for profiling in the lowest portion of the boundary layer, the xlv
NW[5+DiaNk -lkh,T
-. :2 i
i RASS can provide valuable information on plume level wind and temperature stmeture, particularly in lake breeze retum flow, and onshore flow conditions. Great care 'nust be taken in siting egripment to avoid sources of ground clutter. A thorough siting study which includes testing the profiler at candidate locations prior to pennanent installation at the selected site is highly recommended.
in summary, the field monitoring and data analysis conducted during ELOOFFS met most of t objectives set forward at the beginning of the project. In general, all the equipment op tiuuughout the monitoring program, although significant effon on the part of the site ope equipment manufacturer was necessary in order to achieve problems led to lower than expected data recovery (Objective V).
This study provides a detailed data set which focusses on the unique meteorological p nuclear power generating facilities located in coastal environments. The infonnation an resulting from this study are, in general, applicable to any facility which must make e downwind transpan and diffusion of haz.ardous air pollutants in a coastal environment.
se XV
w n h
L Introduction The transition between land and water can complicate attempts to quantify atmospheric conditions found in the coastal zone. His is tme at any shoreline location, including along the southem shore Lake Ontario where a number of nuclear, coal, and gas-fueled power plants are operated? The ~
Eastem Lake Ontario On-shore Flow Field Study (ELOOFFS) was established to address problems Thennal related to dispersion meteorology in the coastal transition zone. Of primary concem are:
Intemal Boundary Layers (TIBL), stability classification methods, and vertical wind speed profiles.-
' Additional issues relate to the application of new remote sensing equipment to monitor the coast L
zone meteorology and the availability of site-specific data for use in verifying mesoscale models.'
Summary of Problems and Objectives De primary objective of ELOOFFS was to collect meteorological data within 10 km of the transition zone in order to characterize transport and diffusion from power generating facilities du
- on-shore flow conditions. Five specific tasks were identified in order to target the research of this project.
Task -1: Monitor Coastal Transition Zone Intemal Boundary Layer Guidance documents issued by the Nuclear Regulatory Commission (NRC) recommend that the ' main meteorological tower at any coastal nuclear power facility be located within the TIBL at all times inl order to properly characterize dispersion conditions over land. The first specific objective of this study was to make measurements of TIBL height and elevated mixing layers in order to detennine the most appropriate location for a meteorological tower to satisfy NRC gusdance.
Knowledge of elevated mixing layers is expected to assist in~ assessing the stability of the atmosphere into which specific plumes.are released.
Task 2: Evaluation of Stability Classification Schemes f A' recent study commissioned by the Empire State Electric Energy Research -
,[
Corporation.(ESEERCO) looked at methods of classifying stability at Nine Mile Nuclear Power Station. Five methods were employed to clacsify stability into one of :
f seven stability classes using data collected with existing monitodng syxems. De study found that stability classification varied from scheme to scheme and that each of -
. the methods suffered from various problems. Because most air pollution models allow 1
__-____.________m_
I w
specification of only one stability class, this presents a problem to specifying stability in the coastal transition zone nemfore, the second objective of the project was to l
address stability classification problems associated with shomline meteorological towes.
Task - 3: Monitor Vertical Wind Profile NRC guidance recom'nends that measumments taken on the primary meteorological tower should be representative of the conditions at potential release elevations. If the highest measurement level on the tower is not at the same elevation as the highest release point, the measumments may not be adequate. At Nine Mile Point, the primary meteorological tower is 200 ft while the highest release point is 430 ft.
Herefore, the third specific objective of this study was to measure winds at release and plume elevations and perfonn an intercomparison between other measurements in order to justify sensing levels.
Task - 4: Detailed Regime Measurements Specific and detailed measurements of the unique meteorological regimes experienced over the southeaster Lake Ontario shore are lacking. To address this short-coming, die fourth specific objective was to make detailed observations of specific l
metcomlogical regimes in support of validation studies related to separate numerical l
modeling studies.
I
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Task - 5: Evaluation of Wind and Remote Sensing Technology l
I ne final objective of the study was to evaluate the potential for wind pmfiling technology as an altemative to tall meteorological towers and/or Doppler Acoustic Sounders (Sodar) for measuring wind speed and direction in the boundary layer.
Project Summary i
T k i involved the installation and operation of thee monostatic acoustic sounders for a period of one year in order to collect infomiation on the boundary layer over Nine Mile Point. De three sounders were placed at locations progressively inland from the shoreline. In this way, the height of the boundary layer as a function of distance from shore was monitomd. From this information, quantificatior of the TIBL and elevated mixing layers was developed.
in Task 2, stability classification schemes were evaluated using existing data sources as well as a l
specially designed 2-to 10ceter meteorological tower for making enhanced micrometeorological measurements. The data collected from this tower allowed the calculation of stability using a variety of methods and comparison with other, routinely used, techniques. An interromparison of all methods 2
?
I
.p-
. leads to recommendations for site-specific stability classification.
m; i l Tower for
. In order to assess the appropriateness of the Nine Mile Point Primary Metcomlog ca estimating wind speed at the release height, a field study was conducted as part of Tas measure the venical wind profile at the site. De field study employed a tethersonde boundary profiling' system to develop a compamtive data set. The tethersonde was flown a under a variety of meteorological conditions. The data set produced was used to compar 200 ft primary tower routinely used at the site. A data base of all measurements was p
- allowing a compamtive analysis between tethersoride and tower data.
t
- Task'4 involved the collection of detailed infonnation during meteorological regimes of sp concem in the coastal zone: on-shore flow fumigation, lake brecres, land breeze, and no level jets.This data is designed for use as verification data for numerical modelers and Finally, Task 5 evaluated the applicability of the new wind and temperature pmfilin use as a potential replacement for tall towers at Nine Mile Point and other nuclear frili elevated wind, stability, and temperature data is required. A 915 MHz profiler and Ra Sounding System (R ASS) were installed and operated concurrently with overall proje The perfonnance of the profiler was evaluated in tenns of data recovery, system rel perfonnance'as compared to other monitoring systems. A final ' recommendation w
~
whether the technology is viable as a replacement for a tall tower.
Benefits of Research Research results presented in this report are beneficial'to power generating facilities coastal tmnsition zone where dispersion metcomlogy is complicated by unique pheno from the land / water interface. De primary objective of this research was to collect m
~
- data within the coastal transition zone in order to better characterize transport and diffu
' power generating facilities located la these areas. The study addresses' reg
-siting of facilities in shoreline areas.
o He results of this field project are recommendations on where to site a meteorologica 3
i
[ 4.-
l.-
E-
to best assess stability within the TIBL: what stability classification technique (s) are best suited for detennining stability in the coastal transition zone for dispersion modeling purposes; what, if any,
. extrapolations are necessary to estimate the wind speeds at various release points; whether results of field studies at Nine Mile Point are applicable to other facilities; and, whether microwave wind profilers are a viable technology for detennining the venical wind profile in suppon of nuclear facility operations.
Report Organization
'Ihis repon is separated into two Volumes. Volume I contains the final repon text. Each section of the final project repon describes one of the five tasks in detall. The sections are organized to be independent repons summarizing the background, research applications, appmach, results, conclusions, and recommendations for each of the tasks outlined above. The reader may skip to that task report which addresses their particular concems. Taken as a whole however, the repon provides imponant details and insights to many of the meteorological issues which are relevant to nuclear facilities located in the coastal zone. Volume 11 provides the appendices which suppon the conclusions and recommendations outlined in Volume'I.
6 4
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Section 1.0 Monitor Coastal Transition Zone Internal Boundary Layer This Section summarizes the results of a monitoring prugram to detect the existence of coas boundary layers along the southeaster shore of Lake Ontario and make recommendations a pixement of a meteorological tower at the Nine Mile Point Nuclear Station (NMP). A br background description of the coastal intemal boundary layer phenomena investigated d study is presented in Section 1.1 and the study goals presented in Section 1.2. Descriptio equipment, monitoring program, and data analysis approach are provided in Section 1 analysis results summarized in Section 1.4. Section 1.5 presents some conclusions and recommendations resulting from this portion of the study.
1.1 Background
1.1.1 Meteorology of the Coastal Transition Zone At the coastal land / water interface, there is a unique step <hange in the surface characteristics which air Dows. De water is characterized by high heat capacity and low surface roughness; d u the temperature of the air over water is slow to change and flow is relatively smooth. On t hand, land surfaces are distinguished by large temperature changes and high surface roughn air over land experiences large temperature variations and flow is more turbulent.
As air flows from one surface type to the other, it is modified at the bottom, gmdually taking o characteristics typical of air resident over the new surface. The depth of the modified surfre lay increases with distance over the "new" surface' type. The layer of modified air near the surfxe referred to as an latemal Boundary Layer (IBL) because it grows within another boundary layer associated with the approach flow or the unmodified air. Two types of IBLs have been identif aerodynamic intemal boundary layer (AIBL) resulting from changes in surface roughne l
thennal intemal boundary layer (TIBL) resulting from changes in surface temperature.
1-1 1
The AIBL and TIBL each have imponant implications for the assessment of sta zone and, therefore, the transpon and diffusion of pollutants. A step change in s such as going from relatively smooth flow over water to more tud>ulent flow l
AIBL, producing a wind profile modification (Figure 1-1) and a change in sta surface temperature results in an adjustment in the vertical temperature profile (Fig likewise, a change in stability. The change in stability from inside to outside of the T measured in terms of the standard deviation of venical velocity (Figure 1-3).
To consider the AIBL and TIBL separately in the coastal zone is not really appropria occurring simultaneously. However, the surfxe roughness change is essentially constan temporal scales while the surface tempemture (land and water) has dmmatic variation ranging from several hours to one year. As a result, the TIBL is substantially ace difficult quantify since it depends on a number of continually changing meteorological parameters.
The most damatic IBLs occur when cold stable air over a lake or oce f
land heated by the daytime sun. His condition develops a TIBL. In order for a T
{
following conditions must exist:
i Wind direction onshom (ie. air flow from water to land).
Stable venical tempemture gradient over water.
f Neutral or unstable vertical temperature gradient over land.
Tme TIBL conditions occur only with unstable venical temperature gradients over lan fumigation under neutral stability classifications is possible, but most often results from mixing rather than thermal imbalances.
He TIBL is important to dispersion meteorology since a phenomena known as sho i
can occur when a pollutant plume intersects the boundary between an elevated stable layer(
)
surfxe-based unstable layer. When an elevated point source exists near the shoreline, plume would initially be emitted into the stable layers above the TIBL provided the win on-shore. However, the plume may eventually intersect the growing TIBL, where of the plume occurs in the unstable air of the TIBL. The sudden downward mixing plume'is referred to as shoreline fumigation. The occurrence of shoreline furnigation l i.
j j
1-2 i
~
3-x:..
increases in ground-level pollutant concentrations closer to the soume than would be expected if the phenomena was not occurring.
The NMP facility is located on the southeaster shore of Lake Ontario near Oswego in New York State, and is therefore subject to the potential of a TIBL meteorological regime. A previous frequency analysis using two years of site-specific meteorological data detennined that on-shore flow occurs approximately 50-percent of the time in the vicinity of the NMP facility (Galson,1990). The ana also showed that on-shore flow with meteorological conditions appropriate for the development of a TIBL occur approximately 5 percent of the time on an annual basis, and over 15 percent of the time during the months of May, June, and July. It was concluded that the occunence of TIBLs and associated shoreline fumigation conditions is potentially imponant when describing the transpon and diffusion of pollutants in the vicinity of NMP and other power genemting facilities with coastal locations.
As part of the Eastem Lake Ontario Meteorological Study-Phase III, a literature review of observations end TIBL formulations was conducted (11 anna,1991). The review found that no studies of TIBLs have been made specific to the Lake Ontario shore. Ilowever, several studies have been condticted on some of the other Great Lakes, including Lake Michigan (Lyons,1975), and Lake Eric (Ponelli, et.al.,1982). lianna (1991) compared previously developed fomiulas to describe die TIB height as a function of inland distance with observed TIBL heights from several field studies.
Empirical TIBL height equations were also compared to the observations.
Ilanna (1991) identified the following difficulties with theoretical expressions for TIBL height when compared to the existing' condition:
'lhe venical position of the TIBL is difficult to verify, since it can be defined as a 1) temperature, wind speed, and/or turbulence discontinuity.
Some observation studies have shown that there may actually be two TIBLs, the top of 2) the layer modified by the surface and the top of a second inner layer in which die boundary layer has reached an equilibrium with the underlying surfre. This situation
~
is funher complicated by TIBLs which form inside sea (lake) breeze circulations.
The wind speed profile (an imponant input to some TIBL height expressions) is not 3) spatially consistent, and can be different over water, at the coasdine, and over land.
1-3
l 4)
Sensible heat flux is not constant with distance from the shoreline. It is expected tha l
l boundary layer feedback will cause the heat flux to increase as the boundary layer i
deepens.
i 5)
The over-water tempenture gradient is not likely to be constant with height. Most boundary layer theories and observations suggest that the potential temperatum gradient is greatest near the surface.
I.
\\
6)
Water and surface temperatures are poorly defined. Temperature shows its largest t
J variation near the surface, and can vary by several degrees between surface skin j
temper.iture (ie. air tempenture 0.1 m above the surface) and the standard tempemture i
measurernent level.
To describe the TIBL height on the southeaster shore of Lake Ontario, Hanna indicated that theoretical equations would be prefemble to empirical equations. However, in real wodd appli the values of some of the pammeters necessary to solve theomtical equations are difficult to define
{
In a:idition, the equations may give unrealistic answers for certain combinations of parameter value Therefore, Hanna secommends using "rubust" empirical equations to estimate TIBL height. Such equations are stable with respect to input data, and agree reasonably well with the results of field experiments.
Specifically, Hanna (1991) recommends using one of the following empirical expressions de approximate the TIBL height (Hmt,in meters) as a function of inland distance (x, in meters):
k OCD (1985): Hmt = 0.1x when xs2000m Hmt = 200m + 0.03(x-2000) when x>2000m Hsu (1988):
Hmt = Ax where A a i. 9, 2.7,1.7, and 1.2 for over-land ir2 stability classes A, B, C, and D, respectively The TIBL heights predicted by these expressions are shown in Figure 1-4. The TIBL height equ}
all show a similar pattem, with the steepest slope near the shore, and decreasing slope farther inlan l
The deepest TIBLs are expected when instability is greatest (ie. Pasquill Stability Class A). 'Ihis j
makes intuitive sense since the convective currents are most intense under high thermal instab thus mixing thmugh a deeper lay is supported thermodynamically. As mentioned previously, TIB existence under neutral boundary layer conditions (ie. Pasquill Stability Class D) is mainly a result o 1
mechanical mixing, and the TIBL is weaker and more difficult to define. The OCD TIBL height 1-4 i
1
y ;_
~ :.a. - -
f model is the most conservative of the approxhes, and requires the user to determine only if appropriate conditions for TIBL development cxist. The lisu model is slighdy less conservative, and requires a slightiy more detailed assessment of the overland stability.
As compared to the unstable TIBL the severse situatiori of warm air advection over a colder surface has received > cry little attention. This situation may exist in winter along the southeast shore of Lake Ontario when warm lake air moves on-shore over cold, often snow covered land. Raynor et. al.
(1979) reponed on the stable IBL on the southem shore of Long Island, and developed an empirical relationship to predict growth of this type of IBL. Like the TIBL, the stable IBL also pmsents a problem when it is necessary to estimate the proper stability. In general, a plume release into or intersecting the stable IBL will remain in the stable layer where more traditional methods are adequate for estimating dispersion. Therefore, this study was intended to focus on the mom volatile conditions pmsented by an unstable TIBL, and cold air advection over a warm surface.
l.:.2 Applications to Nuclear Facilities The meteorological program at Nine Mile Point Nuclear Power Station and all other power generating fxilities employing nucicar technology in the United States is subject to Federal Regulation 10CFR50.47. The regulation is in place to provide prutection for the general public by requiring nuclear power generating fxilities to have adequate facilities to allow the" assessment and monitoring of actual or potential offsite consequences of a radiological emergency." The Nuclear Regulatory Commission has issued the following documentation to provide guidance to nuclear facilities in meeting the requimments of the regulations:
" Recommendations for Meteorological Measurement Programs rnd Atmospheric Diffusion Prediction Methods for Use at Coastal Nuclear Reactor Sites" (NUREG/CR-0936)
" Meteorological Programs in Suppon of Nuclear Power Plants" (NRC Safety Guide 1.23 Revision 1*)
Meteorological data collected in support of the meteorological programs are used for short-and long-tenn dose calculations, and emergency response plume trajectory and arrival times. Regulations and guidance make specific statements regarding the need, location, availability, quality, and type of i
1-5 l
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- meteorological measurements.
- De guidance documents listed above specifically identify coastal intemal bou L'
as a " problem area" with respect to detennining transpon and diffusion from nuclear 4in coas'tal areas. Cunently, the dispersion models employ robust transponable y
4 methods for simulating m the effect of shoreline fumigation on' downwind impacts for pollutant plumes.'In order to support dispersion estimates in areas where coastal intemal boundary layers may be a factor, th
. guidance documentation makes the following recommendations with' respect to mo
.1) -
De primary meteorological tower should be located so that the upper measur is always within the intemal boundary layer..
i
~ 2)
. A secondary meteorological tower should be placed at a location where measurem L
representative of the unmodified marine air can be obtained.
. 3)
' Instrumentation heights on the primary meteorological tower should be represe l-
~
of conditions within the intemal boundary layer while maintaining adequate sep
- between levels so that likely differences measured are greater than the' unc the instrumentation.
'This task is designed to further investigate the TIBL, and provide recommendation
' significance to the problem, specifically to nuclear facilities located in shoieline areas, L
1.2 Study Objective
' he objective of this study is to make measurements of the "I1BL in order to detennine the m
)
anort priate location for a meteorological tower to satisfy NRC guidance. Knowledge of the T i
height will assist in assessing the stability of the air into which specific plumes are releas i
provide required infonnation for the modeling of transport and diffusion of releases from coastal nuclear facilities, specifically the Nine Mile Point Nuclear Station and J.A. Fitzpatrick Nucle
. Plant.
l
- 1.2.1 Study Goal
. The following specific goals were identified as necessary to address the task objectiv I
1 0
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_.-_---..._._._.._-..----.-___.__.__----_D
pmeww -
.s i
I Successfully operate thme monostatic acoustic sounders in onier to collect infonnation 1) on the vertical profile of atmospheric turbulence.
I Develop software to read and interpret the bxkscatter data from the sounders, 2)
Identify the location of elevated mixing layers using automated techniques 3) supplemented with manual inspection by a meteorologist familiar with the operation of the site.
Detemiine the elevation of the TIBL at various inland distances tivough interpretation 4) of the sounder backscatter data during meteorological conditions favorable for TIBL development.
1.2.2 Potential Applications for Research Any utility with a source of atmospheric pollution located in a coastal or shomline area may potentially benefit from improved understanding of the dispersion meteorology in the coastal Detailed observations of the intemal boundary layer as a function of inland distance provides information on the vertical variability of stability pammeters as a plume travels inland. His infonnation may allow development of improved models to better predict the importance and loca of vertical stability layers and the potential for plume trapping or fumigation.
his research provides information of interest to utilities wishing to investigate the potential for bette predicting the dispersion meteorology associated with vertical variations in stability.
1.3 Approach De Nine Mile Point Nuclear Power Station is located on the southeaster shore upstate New York as shown in Figure 1-5. De shoreline mns essentially west to east at the however a bend to a southwest to northeast orientation is located immediately west of the facility.
De terrain slopes upward from the lake, inland, through a series of rolling hills and valleys. The j
elevation of the facility is approximately 270 ft above mean sea level (MSL). Terrain rises to f
approximately 480 ft MSL within 5 km south of the facility, i
Because of its coastal location, NMP is subject to meteorological conditions favomble for the l
1-7 1
l i
development of11BLs. Vuoughout much of the spring and summer months, the land area surrounding Lake Ontario is often warmer than the lake due to daytime solar heating. As a resuit, relatively unstable tempemture profiles develop during the daytime over the land while relatively stable profiles exist over the cooler water. When onshore winds carry the stable lake air onshore, there is a potential for a TIBL to develop and grow with inland distance as the stable lake air is modified from below by the warmer land surface.
1.3.1 Description of the Monitoring Instmmentation In onler to measum the boundary layer and identify elevated mixing layer (such as the TIBL), the single-axis monostatic acoustic sounder was selected. Acoustic sounding equipment is based upon principle that a volume of air scatters incident acousde energy. Scattering is due to wind speed and temperatum discontinuities in the sanpled volume of air. Most of the scattering occurs in the direction of propagation, but a small percentage of the energy is scattered back to the n me. An acoustic sounder transmits a strong acoustic pulse (typically around 100 watts) vertically into the atmosphere and listens for that portion of the transmitted pulse that is scattered back to the transmitter.
The monostatic sounder uses the sane acoustic driver to both transmit and receive the signal with a single vertically pointed antenna. Bistatic sounding systems employ separate transmitting and rec antennae.
Theoretical equations which relate the amount of retum signal to the velocity and thermal structure functions have been developed. The existence of a temperature gradient and small-scale turbulence create local instantaneous temperature differences greater than the mean vertical temperature gmdient.
A strong retum signal can be produced either by an unstable temperature gradient and little wind shear (convective boundary layer) or by a stable potential temperature gradient and large wind shear (stable boundary layer). As a result, qualitative atmospheric stability and temperature profiles can be developed. This stength allows the monstatic acoustic sounder to be used for sampling the bounda between marine and non<narine air during onshore flow.
Monostatic sounders can produce both facsimile and digital outputs of retum signal stmagth for analysis. The facsimile output is essentially a strip chart recording of the strength of retum signal 1-8 1
1 1
mm-
- vr
-mm
versus height for exh acoustic pulse. Dark shading indicates strong signal return while light shading indicates weak. Often, strong retums are associated with boundaries, such as the boundary between modified surface air in a TIBL and unmodified air above the TIBL in on-shore flow. In this way, the height of such mixing layers can be detemiined. Backscatter intensity data obtained using a monostatic sounder is converted from an analog signal to digital representation and stored in a computer for each of a user specified set of range gates or height inemments.
In addition to the qualitative results, one strength of sounders is their ability to detect shifts in the frequency of the transmitted acoustic pulse. Fr quency shifts are caused by the doppler effect and ar directly proportional to the speed of an air parcel moving away from or towards the tmnsmitter. In this way, vertical velocity (W) and standard deviation of vertical velocity (oW) can be calculated in each of the mnge gates. Atmospheric stability can be classified xcording to oW.
Acoustic sounders can reach heights as great as 1000 meters, depending on the atmospheric conditions.110 wever, this mnge is often limited in high winds, precipitation, and high ambient noise level environments. In addition, tixed echo soumes such as buildings and trees must also be avoided.
He limitations in siting acoustic equipment are numerous, and all must be taken into account when detenpining an appropriate location for the system.
1.3.2 Sampling Approach Tluhe acoustic sounders were deployed at positions progressively inland from the shore. He purpose of this arrangement was to allow measurement of the height variation of the boundary layer with distance from shore. Spatial boundary layer height data is critical to satisfying the siting criteria for the primary meteorological tower as outline in NRC guidance documents. The sounders were locat at approximately 1,2.25 and 5.5 km inland along a line nearly perpendicular to the shoreline (Figum 1-5). He ground elevation at exh of the sounders sites,290,312, and 485 ft MSL, respectively, reflects the gradually increasing terrain inland from shore.
De tivee sounders deployed for this study were the Radian Corpontion Echosonde@. Each unit consisted of the following:
1 1-9
)
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_ = _ _ - - _
single, venically pointing antenna operating at 1850 Hz,'
IBM PS/2 Model 30-286 host computer with Echosonde@ controller for signal
+
processing and data storage on magnetic media.'
monocinome graphics monitor for onsite data display and operator use, printer for data backup, e-surge protector and unintenuptable power supply, and e
telephone modem for remote data checks.
+
' The sounders each transmitted 75 Watts of acoustic power using a 150 msec pulse length which repeated every 5 minutes. He retumed pulse (backscatter), was received and convened from an
- analog signal to'a digital signal intensity in teens of power units. Digital backscatter retums were classified into altitude intervals or ga:es, detennined by relating the response time to the transmission time, and calculadng the distance traveled based upon a function of the speed of sound. He sounde each had 200 altitude gates, each gate approximately 4.5 m deep, extending from 30 to 940 m above the ground elevation. He total signal power in each gate was averaged over a 10 to 15 minute and then stored d.igitally on the host computer disk drive. He data was further edited using a background noise estimate made automatically.during periodic non-transmitting times. Upon completion of the av eraging, the power contribution due to this background noise estimate is subtneted from each backscatter power estimate. In addition, pulse' cycles with noise estimates above a specified threshold (typical maximum background noise level), were excluded from the avera process.-
In addition to reconfing of backscatter data from which thermal stmeture may be infened, vertical profiles of the venical wind (W) were derived by measuring the Doppler shift of energy ref to the sounder within each range gate. Doppler measurements in each altitude gate are time-average over 30 minute periods from which a vertical wind speed is derived (Initially, the sounders reconied
' W over 15-minute periods, however, this was changed mid-way througb 'he monitoring program in i
order to improve data recovery rates). Data availability, including range, is dictated by atmospheric siting conditions. As the sounder records the vertical wind speed for each altitude gate and time-averaging interval, the standard deviation of the vertical wind speed (oW) is also computed and recorded.' He oW value from the lowest altitude gate is also convened to an estimate of the i
atmospheric stabil;ty class.
In addition to measuring atmospheric parameters such as backscatter, vertical wind speed, and.
1 - 10 i
stability, the Echosonde automatically employed a bxkscatter pattern recognition scheme which,in canjuncdon with the stability estimate, provided ar. estimate of the mixing height. The automated mixing height calculation scheme has been shown to be accurate within 150% as much as 80-90% of the time. The automated mixing height was recorded to disk along with the other pammeters.
De sounders wem installed in late October,1991, by Radian and Galson technicians and began routine recording on November 1,1991. The systems operated continuously for a period of twelve months. A Galson technician made twice weekly site visits to perform routine maintenance operations such as data backup, operational checks, printer paper pickup /replrement, and snow, ice, and insect removal. Periodic remot kaerrogation of the sites was perfomied by Galson and Radian in onier to assure continuous opemtion and identify / diagnose potential pmblems. Radian performed two maintenance visits during the project in onier to detennine the satisfactory operuting status of the acoustic sounder systems.
Re stored digital bxkscatter, venical velocity, stability, and mixing height data was collected by Galson monthly, and sent to Radian for validation and reporting. All data was quality reviewed by an experienced meteoroloE st familiar with the project and the operation of the sounders. Mixing height i
data was provided monthly to Galson for inclusion in the monthly project progress reports, t
Overall data recovery for the network was excellent. De overall system availability was greater dian 99% of the total possible hours duoughout the one year monitoring period. Data capture statistics for mixing height, vertical velocity and standard deviation of vertical velocity parameters are provided in i
Table 1-1. De major cause for lost data was the system down-time for routine maintenance and data backup, and atmospheric conditions unfavorable for retum echoes. Note that during February,1992, operati= system parameter changes were implemented which improved data recovery for die measured pammeters. Backscatter data recovery remained unaffected.
1.3.3 Data Analysis i
4 Extensive data analysis was necessary to address the objectives of this task. De limited capability of l
the automated mixing height identification algorithm required an attemative approach to assessing the 1 - li
I height of elevated mixing layers and the TIBL in addidon, the sounders produced an extraordinary amount of data requiring soning, averaging, and reduction in order to produce a data record of manageable size. Nearly 220MB of digital sounder data was created as a result of the monitoring.
The majority (over 90%) of this information was bxkscatter data.
%: data analysis in suppon of this task focussed on tu/s areas: Determination of multiple elevated mixing layers and identification of TIBLs. The fo. lowing sub-sections discuss the data analysis associated with these areas.
1.3.3.1 Determination of Elevated Mixing Layers Elevated mixing layers within the acoustic sounder data were detennined by using significant vertical gmdients in the backscatter data to identify mixing layer boundaries. Following averaging and smoothing of the detailed backscatter data, exh of the venical backscr':r data records was pmcessed from the bottom up (ie, beginning at 30 m and ending at 940 m). Increases in backscatter (following correction for acoustic attenuation) were interpreted as mixing layer boundaries. He strength of the bxkscatter gmdient (Ab, where b is the bxkscatter power at any elevation z) and depth of the.
backscatter increase (Az) weit also notec. A Ab value greater than 25 was selected as representing a layer of significant scattering and flagged as a probable mixing layer boundary. Funher, Ab/Az greater than zero was defined as the mixing layer boundary base, and Ab/Az less than zero was defined as the mixing layer boundary top. In order for multiple mixing layers to be defined, two sepamte layers where Ab is greater than 25 are required.
A fn:quency of occurrence analysis of multiple elevated mixing layers was performed following the prugre"ive use of four separate post-processing programs for each day in the sounder records.
Multiple elevated backscatter layers identify a venical stability gradient. The existence of a venical stability gmdient can lead to erroneous estimates of pollutant dispersion since current dispersion models do not allow for venical stability variations. He four progmms used to identify multiple elevated mixing layers are described as follows:
PROC.FOR
- Conven Echosonde@ mw cata archive files to ASCII format J
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- Reformat data in preparation for decoding and avenging
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- Decode mw backscatter data
- Calculate avenge backscatter data MIXDETFOR
- Bin data and smooth (33 bins with 27 m increments)
- Identify scattering layers
- Output number, depth, and strength of scattering layers MIXFREQ.FOR - From MIXDET.FOR output, detennines the occurrence and frequency of muldple mixing layers by identifying layers with Ab>25 In addition to the robust automated procedure outlined above, mixing height data was reviewed by a meteorologist familiar with the pmject to verify the results. Tie results of the muldple mixing height frequency analysis are presented in Section 1.4.
1.3.3.2 Identification of TIBLS Vie identification of TIBLS proved to be extremely difficult due to the apparent dominance of synopdc scale mixing layers, the variable nature of onshore flow conditions, and the complexity of performing detailed review of the digital bxkscatter data files.
Die first step to identifying TIBLs, was to identify hours of onshore flow at NMP. Etis was perfomied using available meteorological data trom the NMP main meteorological tower (9MP) and the ELOOFFS micro-metcomlogical tower (MMT). For the purposes of this analysis, periods of onshore flow were identified using the following criteria:
1)
Wind direction at 9MP 30 ft level between 270 and 40 degrees ij Wind direction at MMT 10 m level between 270 and 40 degrees 3)
Wind direcdon criteria must be met at both 9MP and MMT for at least 2 consecutive hours Over 2,300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> were selected as meeting the onshore flow criteria. In order to identify potendal onshore flow cases which were more likely to support a TIBL across the roustic sounder " network",
the wind direction criteria were further refined to better distinguish periods with onshore flow perpendicular to the shoreline at NMP. In addition, a wind speed criteria was added to eliminate consideration of light and variable wind conditions. Night-time hours were also eliminated from
~
consideration. Die potential TIBL criteria are as follows:
1 - 13
l i
i 1).
Wind direction at 9MP 30 ft level between 325 and 15 degrees 2)
Wind direction at MMT 10 m level between 325 and 15 degrees 3)
Wind speed at 9MP 30 ft level greater than 1.5 m/s
. 4)
Wind speed at MMT 10 m level greater than 1.0 m/s 5)
Solar radiation at MMT greater than 0.02 Langleys/ min Approximately 231 hours0.00267 days <br />0.0642 hours <br />3.819444e-4 weeks <br />8.78955e-5 months <br /> were identified as potential TIBL hours using this selection criteria. It should be noted that the actual number of potential TIBL hours at NMP during the one year monitoring period is higher, however, the wind directions for the eliminated hours would not have been favorable for investigating TIBLs over the sounder networt.
Finally, the best time periods for potential TIBL development were identified using the following additional data reduction criteria in order to assure that conditions sufficient for the development of unstable lapse rates over the land cristed:
1)
Solar radiation measured at MMT greater than or equal to 75% of total possible.
2)
No snow cover reported on ground at the National Weather Service Office in Syracuse, New York (nearest inland snow cover reporting station).
3)
Air temperature measured at the 2 m elevation of the MMT tower should be greater than the climatological lake temperature (no reliable observed lake tempemture data j
was available for the period of record).
Following this final stratification of the data, approximately 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> remained for detailed TsBL investigation. 'Ihe specific time periods identified as potential TIBL hours are detailed in Table 1-2.
Each of the 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> of potential TIBL data was manually inspected by a meteorologist familiar with the project. The hourly averaged backscatter data produced from the routine BSTR2. FOR described
)
above were used rather than the 104ninute data since the fonnat of the higher iesolution data was very cumbersome and tended to be extremely variable.
The results of the TIBL identification and height analysis are pmsented in Section 1.4.
i l
1 - 14 t
ki I
l 1.4 Data Analysis Results 1.4.1 Multiple Mixing Layer Analysis he existence of multiple elevated backscatter layers (mixing layers) is a potential problem for the reliable prediction of plume transpon and diffusion. Multiple mixing layers identify a venic gradient which can lead to erroneous estimates of pollutant dispersion since most dis not allow for venical stability variations. Multiple mixing heights are analogous to TIBLs in that plumes undergo changing dispersion conditions when intersecting the boundaries be layers. Since measurements of stability are generally confined to below 200 ft at NMP releases may be made into mixing layers above the height detected by the standard monitorin Remfore, the occurrence of venical variations in stability may result in poor dispersion predic using the existing monitoring system at NMP.
This analysis attempted to conservatively estimate the fmquency cf the multiple mixing he NMP. As outlined in Section 1.3.3.1, at least two positive venical backscatter gmdients w in the sounder record to define an hour as having multiple mixing heights. The results of t are shown in Table 1-3 and graphically depicted in Figures 1-6 and 1-7. He results indicate tha multiple mixing heights as defined for this study occurred approximately 25% of the 6me on annual basis during the November 1991 through October 1992 monitoring period. His relati frequency of occurrence is potentially significant from a dispersion modeling standpo from the NMP facility.
De period of record showed that multiple mixing heights are most common in early s i
common during late summer and early fall. His distribution is believed to be related to the t
causes:
1 I
Intensity of the noctumal inversion i
Snow cover (Mamh) l Proximity of a cold air source (ie. Lake Ontario) i i
1 - 15
~
___________________o
1 In tenns of the occurrence of multiple mixing heights as a function of the hour of the day, the
{
phenomena appears to be thost common during the early moming period just following sunrise. This is probably related to the breakup of the noctumal inversion, when heating near the surface lifts the nighttime mdiation inversion aloft. Multiple mixing layers are less frequent during the late moming i
i through aftemoon hours when convective mixing is most intense, thus allowing mixing through a layer l.
which is probably deep enough to prevent multiple mixing layers within sounder range.
I d
De existence of multiple mixing layers at NMP warrants further investigation and monitoring due to the critical nature of assessing stability for dispersion predictions of elevated releases. Continuous monitoring of the boundary layer using a sounder which reports detailed brkscatter profiles is recommended as one appmach to observing and identifying elevated mixing layers for operational purposes.
1.4.'2 T1BL Height Analysis He observed meteomlogical data available fmm the 9MP and MMT towers was processed to select time periods for TIBL height analysis in the method outlined in subsection 1.3.3.2, above. As stated above, approximately 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> were identified as potential TIBL hours using the selection criteria. A listing of the time periods selected and their durations (2 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) is provided in Table 1-2.
The total number of hours (84) selected was rather disappointing and somewhat below what was expected. His result is believed to be a reflection of the relatively cool and wet summer experienced in 1992 compared to the 30-year mean. Table 1-4 shows the temperature, precipitation, and sunshine l
departures fmm the 30-year mean as measured at the Syracuse National Weather Service (nearest long-term metcomlogical station) for the expected peak TIBL occurrence period (March thmugh August,1992). He table shows that temperatures averaged below the 30-year mean for all months but May, and were significantly below the mean during March, June, and July. In addition, the l
precipitation and sunshine data indicate that solar input for warming of the land was well below the mean, resulting in less frequent conditions favorable for unstable conditions over the land,
[
consequently reducing the occurrence of lake breezes which may have supported TIBL development.
As a result of the cool / wet / cloudy conditions prevalent during the peak TIBL season of this 1 - 16 I
l,
monitoring study, the number of cases available for study was less than expected.
Following the selection process, the high resolution backscatter data from exh sounder for exh of the identified time periods was manually inspected by a meteorologist familiar with coastal intemal boundary layer phenomena and the acoustic sounders. The purpose of the manual inspection was to identify all potential bxkscatter boundaries in the data records having the TIBL signatum of cool, stable lake air overlying wann, unstable land air. The backscatter signature typically shows high backscatter power values in the lowest mnge gates, decreasing up to some elevation, followed by a region of steady and/or increasing backscatter, with again decreasing values above. De elevated layer of increased acoustic backscatter has been shown to mark the boundary of the cooler, more stable lake air aloft.
De process of reviewing the digital backscatter data manually was extemely tedious, and required many hours of the analyst's time. Tab!c l 2 shows the TIBL events studied and a summary of the findings for each event. Of the 19 events studied in detail, only 5 revealed boundary layers wtuch are believed to be TIBLs with high confidence. He 5 TIBLs identified provided estimated TIBL height infonnation for just 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> of the total recorti. A total of 6 events had suspected TIBLs, however the analist could not verify with high confidence the TIBl. height or backscatter intensity. The remaining events were eliminated either because no evidence of the TIBL could be found or the event was 4
c:;ginal.
The TIBL height as a function of inland distance for each of the identified events is pmsented in Figmes 1-8 tiuuugh 1-12. The estimated TIBL clevations at each of the monitoring sites have been corrected for the ground elevation of the sounder (ie. the effects of terrain are eliminated). In all cases,
' the profiles show the expected pattem of increasing TIBL height with inland distance, with a rapid increase near the shore (assuming the TIBL height at the shoreline is zero) and a slower increase with height funher inland. De exception to this finding is the TIBL which was observed on April 10, I -.
1992, when an almost linear increase with inland distance was observed.
f
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(
f in comparison with the empirical TIBL height equations cutlined in Section 1.0, the few observed TIBLs appear to follow these equations closely. Of particular note is the Apsil 10,1992 case, when f
i f
i 1 - 17 l'
L
w 1 TIBL height showed a gradual decrease thmugh the aftemoon. This corresponded to increasing cloud cover and increasing stability in the surface layer over the land. This decrease in TIBL height with increasing stability is predicted by the lisu model, liowever, caution is recommended in drawing conclusions from this single case since this data set is exuemely limited.
1.5 Conclusions and Recommendations Regulation and guidance applicable to the siting and operation of meteorological instmmentation at nuclear power generating facilities are clear regarding the need to consider the influences of coastal intemal boundary layers. Intemal boundary layers can have a significant imprt on the dispersion of pollutants from facilities located in coastal locations, and should be considered whenever making estimates of air quality and dose impacts for releases in the coastal zone.
However, observation and tracking of the lecation and height of :he TIBL is difficult. For a TIBL height study on Lake Michigan, Lyons (1975) conceded that ".. the TIBL depth as a function of distance from the shoreline is not easily predictable. Simple statistical analysis showed it [the TIBL) to be very poorly related to any single variable or collection of variables." Indeed lianna (1991) funher concedes the uncertainty in identifying the predicted TIBL height, saying ".. the behavior of the TIBL near the shoreline is uncertain because of the fact that near-shore water tempemiums am genemlly warmer than off-shore.", thus making the actual " shoreline" difficult in identify, f
This study attempted to monitor and estimate the height of the TIBL alog the southeaster shore of Lake Ontario using three acoustic sounding systems located at varying distances inland form the shore.
t i
The goal was to detemiine the site-specific characteristics if the TIBL in hopes of justifying the
)i location of the primary meteorological tower at NMP.
}
r i
Based upon the monitoring completed during this study, and the data analysis which followed, the I
following conclusions are made:
I i
The data collected failed to reveal enough verifiable TIBLs to detemiine whether or j
not use of the empirical TIBL height expressions recommended by Hanna (1991) is justified.
l 1 - 18 L
L I
I l
Re limited TIBLs identified d:3 show the expected TIBL shape (ie. rapidly increasing TIBL near the shore, then slower increase farther inland). Use of hourly data help smooth the TIBL variations. Instantaneous TIBLs heights show much more variability.
l A frequency analysis showed that multiple mixing layers occurred over NMP nearly 25% of the Jme during the 1-year monitoring period. The use of acoustic sounders allowed the continuous monitoring of these mixing layers tiuough measurement of acoustic backscatter. Gmdients in the backscatter have been shown to be related to venical gradients in atmospheric stability.
The most complex vertical distributions of stability occur at NMP during early spring on a seasonal basis, and just following sunrise on a daily basis.
Based upon the conclusions outlined, the following recommendations are made:
Dce to the limited observations of TIBLs at NMP, no justification can be made regarding the location of the meteorological tower. We cunent tall tower should be maintained in order to provide the best estimate of release height winds. However, since multiple mixing layers are frequently observed, monitoring through a deep layer of the atmosphere is recommended by employing remote sensing technology.
In order to insure measurement of the stability inside the TIBL, continued operation of the MMT tower at a location approximately I km inland is recommended. At this inland distance,10 m level of the MMT tower is expected to always be within the TIBL.
Use of the OCD TIBL model as a general guideline for detemnining the TIBL height is recommended since the fonnula is simple and believed robust enough to provide reasonable height estimates for most TIBL occurrences.
Funher study is recommended to identify the causes of multiple mixing layers over NMP. The occuntnce and potential impact of multiple mixing layers on the prediction of transport and dispersion fium NMP should be considered. Identification of the causes for multiple mixing layers will enhance prediction of the phenomena.
Continued operation of the Sodar is recommended with the addition of a facsimile output display to allow operators the visual confirm the existence and elevation of mixing layers.
Funher analysis of the voluminous data collected from the roustic sounders is l
l recommended and encouraged. Funher analysis in combination with other data collected during this study may broaden the scope of the TIBL investigation and help clarify marginal cases. It should be noted that studies involving the backscatter data will involve significant labor effon to implement appropriate processing and analysis progmms.
1 - 19 l
- i
.i 1.6' References -
Arya, S.P.,1988. Introduction to Micrometeorology. Acedemic Pmss, San Diego, CA.
Hanna. S.R., L.L. Schulman, R.J. Paine, J.E. Pliem and M. Baer,1985. Development and Evaluation of the Offshore and Coastal Diffusion Model (OCD). J. Air Poll. Control Assoc.,35,10391047.
Hanna, D.R.,1991. Review of Formulas and Observations of ThermalInternal Boundary Layers in Shoreline Environments. Final Task Report for ESEERCO Project EP 88-6. Empire State Electric Energy Research Corporation, New York, N.Y.
Hsu, S.A.,1988. Coastal Meteorology. Acedemic Ptess, San Diego, CA.
Lyons, W.A.,1975. hrbulent Diffusion and Pollutant Transport in Shoreline Environments. Lectures in Air Pollution and Environmentalimpact Analyses, American Meteorological Society, Boston, MA.
NRC,1979. Recommendations for Meteorological Measurement Programs and Atmospheric Diffusion -
Prediction Methods for Use at Coastal Nuclear Reactor Sites. NUREGICR-0936. Nuclear Regulatory Commission, Washington, D.C.~
NRC,1980. Proposed Revision 1* to Regulatory Guide 1.23: Meteorological Programs in Support of Nuclear Power Plants. U.S. Nuclear Regulatory Commission,' Washington, D.C.
Portelli, R.V.,1982. The Nanticoke Shoreline Dispersion Experiment, June 1978 - 1: Experimental Design and Progmm Overview. Atmos. Environ., 16,413-421.
Raynor, G.S., S. Sethuraman, R.M. Brown,1979. Formation and Characteristics of Coastal Intemal Boundary Layers During Onshore Flows. Boundary layer Meteorology, 16, 487-514.
1 - 20
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u Table 1-2.
. Time Periods investigated for Potential TIBL Identification Date Stan Time End Time
. Duration Notes (EST)'
(EST)
(hrs)
(See Below).
'l1/1/91
.1200 1445 2.75 (1)
~
3/5/92 1315 1530 2.25 (2) 4/8/92 0730 1100'
'3.50 (I)
'4/10/92 1315 1745 4.50 (2) 4/15/92 1100 1330.
2.50 (1) 4/24/92:
1130 1445 3.25
'(3) '
5/6/92' 0945 1245 3.00 (2) 5/14/92 0630 1100 4.50 (2) 5/15/92 1330'
.1600 2.25 -
(2)
'5/18/92 0630 1930 12.50 (3)1 5/20/92 1130 1630 5.00 (3) 5/25/92 0915 iM30 9.25 (4)
.5/29/92 1130 1345 2.25 (3) 6/15/92 0845 1315 4.50 (3) 6/16/92 0945 1515 5.50 (4) -
7/2/92 0945 1415 4.50 (4)
I 9/9/92 1045 1400 3.25 (3) i 9/13/92
- 1400, 1600 2.00 (4) i f
10n/92 1015 1630 6.25 (3)
Land / Water temperature diffen:nce marginal (ie. within 1 C). No TIBL Notes: (1) identified.'
TIBL identified with high confidence in xoustic sounder data. Detailed in (2) report.
TIBL suspected in xoustic sounder data, but confidence low.
(3)
(4)
No TIBL identified in acoustic sounder data.
1-34
i t!
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I Table 1-3 i
1 Frequency (%) of Multiple Mixing Layers November 1991 through October 1992
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l
~
Month IIO UR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC TOTAL 0
16 36 42 40 29 27 45 42 23 17 30 29 31 1
l 1
23 28 23 43 29 20 23 26 30 20 13 16 24 2
26 28 29 43 29 17 23 29 17 20 17 16 24 3
26 28 29 33 36 40 23 32 20 17 23 16 27 4
10 32 29 47 76 30 32 23 23 20 17 29 26 5
19 32 39 50 36 20 29 16 20 3
27 19 26 l
6 29 20 32 57 32 20 19 16 17 23 27 26 27 7
23 16 42 53 32 47 23 19 20 13 30 32 29 8
26 32 45 47 45 37 36 39 40 13 23 26 34
)
9 23 36 45 60 26 17 29 26 30 17 33 26 30 l
j 10 23 36 32 47 10 27 to 16 30 13 20 10 22 i!
26 20 52 50 19 to 10 to 20 10 23 23 23 12 26 36 52 43 29 0
7 16 3
13 27 16 22
,i I
13 23 12 55 60 to 7
19 7
to 13 27 10 21 l
14 16 8
34 43 10 10 10 7
13 13 27 7
17 15 23 24 39 53 13 10 7
19 7
3 20 19 20 l
16 26 20 39 40 23 13 10 10 10 17 33 26 22 17 42 16 42 53 7
27 13 0
7 to 23 26 22 18 23 24 29 43 10 10 19 0
13 17 23 29 20 19 19 24 29 50 29 33 23 3
23 30 33 26 27 20 19 24 29 37 29 33 16 26 23 23 20 26 25 21 32 24 45 33 32 30 23 45 13 23 17 19 25 i
i 22 19 28 29 47 29 30 26 26 23 23 17 16 26
^
23 to 32 29 47 20 37 23 32 20 20 17 32 26 "lDTAL 23 26 37 47 24 23 21 20 19 16 24 22 25 Note: Shading highlights occummces greater than 50%
l-35 l
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N Table 1 1 l-Observed Temperature, Precipitation and Sunshine Conditions..
- Syracuse, NY 1992 I.
l I
Temperature Precipitation Percent of Possible Sunshine' Month Depanure ('F)
Departure (in) 1992 30-year Meari March
- -4.0
+0.69 42-46' l
' April-
-1.7
+0.20 46 50 May
+0.5
+2.05.
.58 55 4
I June
-2.3
-1.85 63 59 a
4 l
July
.-3.6
+4.24 44 64-(
August
-1.8
- -1.13 -
57'
'59'
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Section 2.0 Evaluation of Stability Classification Schemes This section pmsents the resuhs of a one-year evaluation of various atmospheric stability classification schemes in the shomline zone near the vicinity of the Nine Mile Point Nuclear Facility (NMP),
Classification of stability is an imponant input pammeter to models which describe the tmnsport and dispersion of effluent from the frility. A variety of techniques exist for defining the atmospheric stability. A special micrometeorological tower was installed near NMP to collect data allowing the calculation of stability using a variety of techniques. These calculations wem compared with stability classifications from an existing 200 ft meteorological tower. A background description of stability classification is provided in Section 2.1 and the study objective pmsenting in Section 2.2. A summary of the monitoring equipment and the various stability classification schemes calculated is provided in Section 23, and the data analysis msults in Section 2.4. Conclusions and commendations are provided in Section 2.5.
2.1 Background
Knowledge of the atmospheric stability is critical in most applications involving pmdiction of pollutant dispersion since the stability defines the degree to which the effluent will spread in both the vertical and horizontal dimensions as it tmvels away from the point of emission. Most pollutant impact and dispersion pmdictions are performed with models employing the Gaussian plume approrh. Gaussian twme Models employ a thme< dimensional axis system of downwind, cm;; wind and venical components; assume that the concentrations from a continuously emitting plume are proponional to the emission rate; and that these ancentrations are diluted by the wind at the point of emission at a j
rate inversely proponional to the wind spee<!; and that the time-averaged (generally about 1-hour)
]
pollutant concentrations crosswind and venically near the source are well described by gaussian or normal distributions (Tumer,1984).
I l
The degme of spmading is a function of the atmospheric stability. 'Ihe standard deviations of plume concentration in the venical (o,) and horizontal (o,) dimensions are empirically mlated to the level of atmospheric turbulence (stability) with distance from the source. One inherent uncenainty in Gaussian 2-1 l
m Piume Modeling results fmm the complex and random nature of the atmospheric turbulence which controls dispersio t Models must panuneterize this random complexity but, by definition, cannot describe it completely.
2.1.1 Stability Classification Schemes Atmospheric stability is a function of both thennal and mechanical interactions between the surfxe and air overlying the surface. In the case of thennally-based interactions, during the day, solar heating of the ground in tum heats the air in contact with the ground, resulting in warmer, less dense air undemeath cooler, dense air. This results in an "over turning" of the atmosphere with wanner air rising and being " replaced" by cooler air. His thennal turbulence describes an unstable atmosphere.
Altematively, at night, radiative cooling of the ground cools the air in contact with it, leaving cooler, dense air undemeath warmer, less dense air. The result is a thennally stable condition. In the case of mechanical atmospherics twbulence, the interaction of horizontally transported air with the ground surfxe is the basis for the production of turbulence. In other words, air traveling over a rough surface (e.E. forests, hills, mountains, buildings, etc.) is relatively unstable compared to air traveling over smooth surfaces (e.g. water, mown fields, snow, etc.).
Once the characteristic air motions of stable and unstable atmospheric conditions are understood, the implications to the dispersion and spreading of pollution plumes become clear. Under unstable l
conditions, a high level of turbulence results in rapid mixing and dispersion of the pollutant in both I
L the vertical and horizontal dimensions. In a stable atmosphere, turbulence is suppressed, leading to
[
slow dispersion of pollutant plumes.
f I.
Atmospheric stability can vary significantly on a daily basis, ranging from an extremely stable atmosphere during a clear, cool, calm night, to a very unstable atmosphere during a warm, sunny day.
j In general, thennally-based causes result in the wide variations over the course of a day, while mechanically-based causes are slower to change. 'Ihe situation is complicated somewhat, particularly t
in the sicinity of a large water body due to the differing heat capacity of water relative to the land.
At night, the water can be a heat source, resulting in unstable conditions even though night is typically considered relatively stable due to the lack of solar influence, t
6 2-2 l
?
~
i t
i Parameterization of stability for the purposes of dispersion modeling has been investigated by a number scientists since gaussian plume models first came into wide use. The infinite combination of atmospheric stability and dispersion characteristics necessitated stability pammeterization (classification)in order to account for the random nature of atmospheric turbulence while providing a computationally straight forward method of predicting dispersion. Classification of the degree of stability (Extremely stable, slighdy stable, neutral, slightly unstable, extremely unstable) has been perfonned for many decades. The common practice of defining stability into one of six (A duough F) or seven (A duough G) stability classes was introduced by Pasquill, where A is least stable, F (or G) is most stable, and D is neutrally stable. These stability classes are then used to detennine dispersion coefficients for use in the Gaussian plume equation using empirically derived relationship.
Stability classification techniques employing routinely available meteorological data (such as that obtainable from National Weather Service observations) have been developed which use observations of wind speed and cloud cover. Altemative techniques using combinations of various measurements of solar radiation, net radiation, standard deviation of wind direction, and vertical wind and temperature prufiles have also been applied.
2.l.2 Applications to Nuclear Facilities In compliance with Federal Regulation 10CFR50.47 regarding emergency planning, nuclear power generating facilities in the United States are required to have " adequate methods, systems, and equipmcrt fw assessing and mcaitoring of actual or potential offsite consequences of a radiological cmcrgency condition." In order to meet the meteorological aspects of this regulation, nuclear power 1
f generators must have the capability of making near real-time predictions of the transport and diffusion l
of effluent from their facilides. In order to make such predictions, meteorological data capable of describing ti, atmospheric stability is vital.
As introduced above and described in greater detail in Section 2.3, many different approaches have l
been applied to calculate the stability class. However agreement between the various techniques 1tas been shown to be poor, making selection of the appropriate technique in an operational setting difficult. This situation is complicated further in coastal areas, where inhomogeneities in surface characteristics result in spatially varying stability classes near the surface. As a consequence, 2-3
7 comparisons of the various stability classification schemes is necessary to determine which most reasonably repmsent the stability and dispersive characteristics of the atmosphere within the mixed layer.
2.2 Study Objective The objective of this task was to install and operate a 10 m micrometeorological tower f one year in the vicinity of NMP for the purpose of evaluating various atmospheric stability classification techniques.
2.2.1 Study Goal j
'Ihe goal of this task was to successfully opente the 10 m micrometeorological tower for a one year, develop software to calculate stability class frum the data using seven different s classification methods, intercompare the stability calculations from the micrometeorological tower and existing 200 ft meteorological tower, and evaluate the various stability classes for use in the shoreline envimmnent of NMP.
2.2.2 Potential Applications for research t
I a
l As indicated in the task objectives, the evaluation of various stability classification schemes
}
l will serve as the basis for identifying those schemes which are appropriate for use as input parameters to models predicting the transport and diffusion of pollutants in a shoreline location. This res l
provides information of interest to utilities that must perfoon dispersion modeling in coasta i
where use of various schemes can result incorrect stability classification for the observed meteorological condition.
{
2.3 Approach
)
j f
In order to collect dai for evaluating the various stability classification techniques, a 104neter meteorological tower was installed approximately I km southwest of NMP for a period of 12 24
y Re following describes the monitoring system including the instrumentations installed, the data validation and calibration methods, and a description of the various stability classification schemes using the data.
I o
2.3.1 Description of Mor.itoring System A 10-meter meteorological tower (MMT) was located in an open area appmximately 0.75 km f Lake Ontario on the southeaster shore (See Table 1-x and Figure 1-x). Instrumentation on tids measured the following parameters:
Wind speed at 2 and 10 m, Wind direction at 10 m, Standard deviation of wind direction at 10 m, Temperature at 2 m, Temperature difference between 2 and 10 m, Solar radiation, and Net-radiation.
A schematic representation of the installed tower is shown in Figure 2-1.
Since the height difference of temperature and wind speed measurements was so small the wind speed and temperature were also small. 'Dds necessitated careful selection of the s used to make the measuitments. All instrumention selected met or exceeded the precision a accuracy requirements oudined in the USEPA On-site Meteorological Monitoring Prog for Regulatory Modeling Applications (USEPA,1987). In addition, a strict quality contml pro including six full systems calibrations and twice weekly site visits by the site operator a quality data with a very high data recovery rate. The final data recovery statistics for pammeters are provide in Table 2-1.
2.3.2 Sampling Technique and Data Validation Data was stored digitally on a data logger, and avemged for later analysis. Averages w all parameters at 154ninute intervals. Data was routinely downloaded to a central c week. Raw data files were merged with the complete data base, then passed through a screen program designed to note and flag questionable data. Flagged data were review 1
2-5
familiar with the operation of the site. Discrepancies were resolved where possible and corrective action taken when necessary. Data validation procedures were in compliance with USEPA recommended techniques, and questionable data was removed from further analysis. All stability classifications discussed in the next section were calculated during post-processing of the validated data file.
2.3.3 Data Analysis i
i Using the data from the micrometeorological tower, a variety of stability classifications were calculated for a period of 1-year. Stability data were available every fifteen minutes. Following is a brief overview of the seven stability classification techniques used to analyze the unique situation observed at a Lake Ontario site.
2.3.3.1 Objective Technique In onier to provide a baseline stability class against which to judge the performance of the other stability classification techniques, an objective scheme was employed to determine baschne Pasquill stability classes (Pasquill 1961). De technique uses the 10 meter wind speed, time ? day, change in temperature between 2 and 10 meters, and the cloud cover (tluough solar radiation;.a classify stability for 15-minute periods. Day and night were detennined using the USEPA recommended approrh (night = one hour before sunset to one hour after sunrise). He technique is summarized in Table 2-2.
2.3.3.2 Sigma-theta he sigma theta stability classification technique uses the standard deviation of horizontal wind disection as an indicator of atmospheric stability. De most commonly applied technique is that recommended by the USEPA (1987), where high values of sigma-theta are associated with unstable stability classes, and lower values with stable conditions. Wind speeds are also incorporated into the j
i method, by restricting the stability class to neutral anytime winds are above 6 m/s.
1 This technique is relatively easy to apply in practice, however it is limited to xtual measurement of horizontal stability, while failing to explicitly measure vertical stability. Stabilities are restricted to unstable and neutral classes during the day, and neutral and stable classes during the night. This latter 2-6 h
l t
l l
adjustment is suggested in ortler to account for reduced thennal fluxes between the ground and I
atmosphere at night (no solar heating), and the increased Ouxes during the day (solar heating).
In addition to the adjustment of stability class tused upon the wind speed, adjustments have been suggested to account for site-specific influences which rnay create localized mechanical turbulence.
De base category boundaries were established for sites with a ruughness length (z ) of 15 cm.
However, if the monitoring site has a roughness length other than 15 cm, a category adjustment technique was proposed by Irwin (1980). The technique employs a conection to the stability boundaries based upon the following:
c (4)=o (15cm)x( )as e
o For the micrometeorological tower, the average surface roughness was determined for each of eight wind direction sectors (N, NE, E,.... etc.), and the stability categories adjusted by the appropriate amount. The average surfxe roughness for exh sector was determined using the following equation developed fium the neutml wind profile and proposed by Schuhnan and Haga (1991):
4.zexp(4.68) o (O e
Table 2-3 details the boundaries of standard and site-specific sigma-theta techniques employed in the analysis of the data. Note that the data from the 9MP tower used 'he NPC approach which does not employ a conection to the sigma-theta category values for surfxe roughness or to stability categories for day.,r night. Stability calculated using data from the 10 m tower was deterrr!ned using the standard USEPA techniques, both with and without corrections to the sigma-theta categories to xcount for surface roughness and with adjustments to stability class for day and night, as detailed in Table 2-3.
2.3.3.3 Delta-temperature Direct measurement of the vertical temperature gradient (delta-temperature) between two specific elevations is another technique for classifying stability. Lapse ra:es less than neutral are considen d f
unstable, while conditions are classified as stable when the lapse rate is greater than neutral. He 2-7
NRC recommends measurement of delta-temperature between 10 and 60 meters, as well as between l
10 meters and a higher elevation representative of the stack release height. This technique is independent of wind speed, however no modification is perfonned to protect against stable classes occuning during the day or unstable conditions being selected at night. Table 2-4 provides the NRC delta-temperature stability classification criteria.
Altematively, the USEPA (1993) has suggested measurements of delta-temperature at lower elevations (between 2-and 10- meters), which is likely to produce observations more sensitive to thermal fluxes between the atmosphere and the ground. However, USEPA suggests using the technique as a substitute for sigma-theta at night when wind speeds are frequently light and sigma-theta measurements can indicate unstable conditions even though the lapse rate is stable. He USEPA delta-temperature method includes an adjustment to the stability class depending on the wind speed.
2.3.3.4 Solar Radiation / Delta-Temperature In order to better justify the effects of solar heating on stability, USEPA (1993) suggested that stability classification using a combination between the delta-temperature method and actual measurements of incoming solar radiation at the surface might be appropriate. He delta temperature method is recommended for detennining stability classes during the night hours, while during the day, solar radiation measurements are used. High values of incoming solar radiation indicate significant solar heating and unstable conditions, while low values demonstrate limited solar heating and more stable conditions.
Apin, the stability classes are adjusted to account for the effects of mechanical mixing using wind
{
speed data for both day and night. Stabilities are restricted to unstable and neutral classes during the
{
day, and neutml and stable classes during the night. He classification criteria are presented in Table f
2-5.
2.3.3.5 Net Radiation and Wind Speed Another stability classification method makes use of net radiation measurements and wind speed as proposed by Williamson and Krenmayer (1980). The concept of this techrdque is to better account for
)
the interaction of thennal fluxes between the atmosphere and the ground. Condivons are said to be unstable with low wind speed and high net radiation values, and more stable with high wind speed f
f 2-8 l
?
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I 4
l L
i
and low net radiation.
Again, as with other techniques, stabilities are restdcted to unstable and neuted classes during the day, and neutral and stable classes during the night. In addidon, net radiation limits used in identifying stability classes vary to account for order of magnitude changes in net radiation values between day and night. De stability classification criteria are presented in Table 2-6.
2.3.3.6 Solar Radiation and Wind Speed (DayyNet Radiation and Wind Speed (Night)
An altemative to using net mdiation and wind speed for the entire day is to use solar radiation measurements instead of net mdiation during the day (Willianson and IGenmayer,1980). This technique is similar to the net radiation method described above, with unstable classifications during low wind speed and high solar radiation, ar,d more neutral stabilities with high wind speed and low solar radiation values. Again, stable classes are not allowed during the day. He night-time stability criteria are the same as those determined Section 2.3.3.5, above, while the daytime stability criteria are shown in Table 2-7.
2.3.3.7 Richardson's and Bulk Richardson's Numbers Recently, improved accuracy of commen:ial metcomlogical instrumentation has allowed the measurement of more detailed meteorological quantities, and thus stability classifications that better account for both thennal and mechanical turbulence. Both the Richardson's and Bulk Richard numbers are closer to an actual measurement of stability, since they use both lapse rate and venical wmd speed gmdient as measures of the production of convective and mechanical turbulence (Schulman and llaga,1991).
De Richardson's number is defined by the following equation:
at.K((org/az )
se T
bz)2 where g a gravitational acceleration, T a surface temperature, 60/6z a venical change in potential temperature, and Su/5z a vertical change in wind speed.
l Negative Richardson's numbers are classified as unstable because convective turbulence is indicated b 29 1
s
the negative 60/5z tenn. Positive Richardson's numbers are stable since the positive 50/Sz tenn indicates that convective trbulence is suppressed. Under neutral conditions, the Richardson's number j
appmaches zero, indicating that convective and mechanical turbulence are equally important. No adjustments to the obsesved stability are made for day or night conditions, thus unstable stabilities can occur at night and stable conditions during the day.
J The Richardson's number limits used to categorize Pasquill stabilities were detennined using the technique described by Schulman and Haga (1991) whem m._(#L)&4 4*v L is defined as the Monin-Obukov length and is the depth of the surface layer dominated by mechanical turbulence. The z tenn is the geometric mean height of the two measurement levels. He tenns $h and $m represent the temperature and wind speed profiles for non-neutral conditions and are a function of z and L. As described by Schulman and liaga, the values of L as a function of mughness length (z ) using a series of equations fit the a graph developed by Golder (1972) relating stability class to L.
he Bulk Richardson's number is given by the following expression:
%=f(
, )t*
Re parumeters are defined as previously except u is the 10m wind speco. From an operational standpoint, this technique is simpler to apply than the Richardson's number in that wind speed need only be measured at one level. He response of the Bulk Richardson's number is essentially the same as with the Richardson's number.
He stability limits of the Bulk Richardson's number can be calculated from the Richardson's number limits by M&L m,-
[In(#z)-9):
2 - 10 i
y-i where the tenns are as described previously except for y which is a correction to the logarithmic wind prufile and is a function of c, z, and L 2.3.4 Data Analysis in aldition to calculating various stability classes using the MMT data, data from the 30 ft,100 ft, and l
200 ft levels of the NMP 9MP tower were also treated. Stab 3ity classes were detennined using the techniques applied cunently applied at NMP, namely sigma-theta (without correction for wind spee j
and surface mughness) and delta-temperature (200-30 ft and 100-30 ft). The stability classification criteria for sigma-theta and delta-temperature were defined as in Tables 2-3 and 2-4, respecaely.
2.4 Data Analysis Results Validated fifteen 4ninute stability classifications for each of the methods described in Section 2.3 are pmvided sepamtely on computer disk. Frequency distributions of all stability classification techn developed using the MMT and 9MP data are pmvided in Appendix A. De frequency distributions are pmvided for all hours combined, as well as sepamted by various site-specific criteria (Season, Flow Direction, and Time of Day).
De stability frequency tables show wide variation between the various stability classification techniques. De widely used and tested sigma-theta technique shows the expected tendency to a normal distribution centered around neutml stability. De delta-temperature technilue also shows some trend toward a nonnal distribution, however, some radical departure is noted. He 30 to 200 ft 9MP delta-temperature distribution appears to be more appmpriate than the 2 to 10 m or 30 to 100 ft i
f appmaches. De MMT solar radiation (day), delta-temperature (night) also appears to show the expected distribution of stabilities. De less used and tested Richardson's number and Williamso Krenmayer techniques are more radical in there stability distributions, tending to predict either stable or unstable conditions and minimal neutral flow.
i Separation of the data by onshore flow (wind directions between 245' and 25 ) and offshore flow (wind directions between 85* and 230 ) show that most techniques have the expected responses to 2 - 11 l
l l
i I
differing flow conditions. In general, more unstable classes were observed during onshom flow when compared to offshore. This is likely due to the effect of onshom advection of unstable lake air, particularly in winter, and the prevalence of a stable, offshore flowing land breeze at night. The significant excepdon to this result is observed in the sigma-theta results, particularly at the 9MP 100 l
and 200 ft levels. Since the sigma-theta technique was designed using 10 m data, responses at 100 and 200 ft elevations are not appropriate.
The results of a joint frequency analysis of the stability classification techniques as compared to the baseline objective stability detennination are presented in Tables 2-8 through 219. These tables emphasize the variability obtained between the various stability classification techniques, and highlight the difficulty in selecting an appropriate stability classification technique.
As shown in Table 2-8, the 2 to 10 m delta-temperature technique tends to be more stable than the objective method at night and slightly less stable during the day. This a result of the use of 2 to 10 m delta temperature which responds more dmmatically to the surface heating during the day, resulting in the development of a super-adiabatic lapse rate near the surface, and significant surface cooling at night and the development of a strong surface based inversion, particularly under clear sky conditions.
Typically, one would expect delta-temperature measun.ments taken over a Idgher elevation (e.g. 30 to 200 ft) to show less dramatic variation and possibly closer correlation with stability classes developed from the objective technique.
In general, the sigma-theta method of stability classification showed generally good agreement with the objective method, but tended to be less stable at night (Table 2-9). This results in an over prediction of neutral stability (D). It is believed that this results fem meander of the night-time wind direction even though the technique employs a nighttime wind speed correction. Perhaps the development and variation ofland breeze and drainage winds at this particular site require a modified j
wind speed conection scheme at night. Altematively, some of the increase in neutml stabilities may be accounted for by unstable day-time conditions being classified as neutral. This could result fmm i
t an over-estimation of the site-specific surface roughness correction.
t l
I
\\
Since the objective scheme and the solar radiation / delta-temperature method are closely related, little i
2 - 12 l
l 1
l difference is noted in the predicted stability classes between the two techniques. The results of this joint frequency analysis are shown in Table 2-10.
I i
Both the Willianson and Krenmayer methods (wind speed conected net-radiation and solar f-radiation / net-radiation) show significant differences from the objecdve scheme and require additional
~
analysis (Table 211 and Table 2-12, respectively). In both cases, the methods predicted less stable conditions during the day and more stable conditions at night. It is believed that this is due to the inclusion of net-radiation, widch is sensitive to local ground cover conditions. Subjective observations over the course of monitoring indicated that the MMT site ground cover had, on avemge, a slighdy legher albedo than the surroundings witlun 1 km since the immediate location around the tower was mown grass while much of the area is thickly green with bushes and trees. Another interesting observation is the lack of "E" stability classes at the site predicted by the Williamson and Krenmayer methods. Tids is believed to be a site specific feature, but is deserving of further investigation.
Both the Richardson's Number and the Bulk Richardson's Number were expected to provide the most realistic assessment of stability due to the methods' xcounting of both thennal and mechanical stability (Schulman and if aga,1991). liowever, as shown in Tables 2-13 and 2-14, the tecimiques tend to be more radical than any of the other methods in that they tend to predict either very unstable or very stable conditions with little considention for neutral conditions. This is a little surprising since the monitoring location tended to be fairly windy, resulting in greater mechanical mixing which should lead to frequent observations of neutral stability. These techniques are mther complex due to the " dynamic" measurements required. Further investigation beyond the scope of this study would be appropriate, perhaps to funher adjust the stability class mnges on a site-specific basis.
Comparison of the 9MP tower stabiltiy classifications with the objective scheme from the 2 to 10 m tower are provided in Table 215 through 2-19. Tables 2-15,2-16, and 2-17 show the resuits for sigma-theta measurements at the 30,100, and 200 ft levels, respectively.
1 2.5 Conclusions and Recommendations Regubc:y schemes for stability classification have been developed to be easily transportable to a variety oflccations. The results of this study show that indiscriminate use of any given stability 4
2 13 j
f
)
r l
1 classification technique can lead to estimates of stability that are widely diffemnt from that expected j
using traditional methods. In selecting a stability classification technique, it is impodant to carefully consider the siting and vertical extent of tower-based measurements. Fmm this analysis, the follawing conclusions can be dmwn:
Local conditions must be factored into a detennination of the most appmpriate stability class and, therefom, the selection of appropriate dispersion coefficients. In I
cases involving complex meteorology (i.e. coastal zones), consideration should be given to the collection of stability data at heights close to release elevation. Ground level releases should employ near surface stability classifications sucn as those obtained using the 2 to 10 m micrometeorological tower, while elevated releases should empty stability classes representative of the height of elease such as those obtained from the 200 ft meteorological tower (9MP).
In addition to considering siting and measurement protocol, the boundaries used to define specific stability classes may requite adjustment on a case-by case basis. Tids is particularly true of the sigma-theta, Richardson's and Bulk Richardson's Number, aad Williamson and Krenmayer techniques.
[
When employing the sigma-theta method for specifying stability from the 30 ft level of the 9MP tower, a site-specific correction for swface roughness is suggested to l
account for localized mechanical effects.
100 and 200 ft sigma-theta should not be used to detennine stability class using l
exisiting classification criteria since these were developed using 10 m data. If 100 and l
200 ft classification are used, the stability classification criteria should be revised to reflect the different mechanical and themial stability conditions found at higher elevations.
For elevated releases, use of the 30 to 200 ft delta-tempemture is recommended to account for the broad vertical variation in stability resulting fonn near-surface thennal fluxes and mechanical effects and smoother elevated flow.
For near-surface releases, use of the sigma-thetc. method from either the 2 to 10 m tower or the 30 ft level of the 9MP tower are recommended. 'Ihe sigma-theta inethod should include a site specific surface roughness correctim developed similarly to that I
described above.
Funher analysis of the data collected is recommended. A review of the tendency for some techniques to predict stability extremes rather than a distribution as is typically observed using traditional stability j
classification techniques is necessary. Further analysis may allow definition of site specific stability class boundaries for the Richardson's Number and Bulk Richardson's number criteria.
J t
2 - 14 i
L
-. y - - - __
i bi it for use at in summary, generalized limitations on stability classif cations may e nappropr a e shoreline k) cations where complex meteorological phenomena result in varying stabiFly in both the horizontal and vertical diinensions. In particular, stability classification methods which assume that the only source of thennal heating is solar radiation may be inappropriate in environments where the I
advection of unstable air may be important, such as that encountered in a coastal environment.
6 I
i 0
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N?. 6 ReferenEs:
I s
. Bowen, B.M., J.M. Dewar, AJ. Chen,1983. Stabiltiy Class Determinadon: A Comparison for One
=jl
. Site. Extended Abstracts of the Sixth Symposium on Turbulence 'and Dijfusion, American L
,+
1Metcomlogical Society, Boston, MA, pp. 211-214.
4 Irwin, J.S.1980. Dispersior Estimate Seggestion #8: Estimatution of Pasquill Stab;Uty Categories.'
i
- Docket Noi A-80-46, !!-b 10. U.S. Environmental Protection Agency, Research Triangle Park, N.C.
. j 2
' NRC,"198_0 Proposed Revision 1,* to Re atory Guide 1.23: Meteorological Programs in Support
. I Nuclear Ponier Plants.' U.S. Nuclear Regulatory Commission, Washington, D.C I-Pasquill, F.,1961. The Estimation of the Dispersion of Windbome Material. Meteorology Magazine.
- 90,33-49.J a
Sihulman, L.L. and C.M. Haga,1991.' A Comparison of Turbulence Classification Schemes Near Eastem Lake Ontario. Final Task Report for ESEERCO Project EP 88-6. Empite State Electric Energy
+ Research Corporation New Yei NY l
T, Tumer, D.B.,19M. A diffusion model for an urban area. Journal of Applied Meteorology,3,83-91.
USEPA,- 1987.'Onsite Meteorological Program Guidancefor Regulatory Modeling Applications. U.S.
Environmental Protection Agency, Research Triangle Park, N.C.
[
l; USEPA',1993. Guideline on air quality models (revised) with Supplement B. U.S. Environmental Protection' Agency, R6 search Triangle Park, N.C.
f 1
.Williamson, IlJ..und R.R. Krenmayer,1980. Analysis of the relationship between Tumer's stability classifications and wind speed and direct measurement of net mdiation. Conference Papersfor the f-Second Joint Conference on Applications of Air Pollution Meteorology, American Meteorological t
Society, Boston, MA, pp. 777-780.
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i Table 2-2. Summary of the Objective Stability Classification Scheme used as the baseline I
for comparison to attemative schemes.
Day Nicht Incoming Sole Radiation (ly/ min)
Delta Temperatum Wind Speed
> 1.0 0.5 to 1.0
< 0.5 (r,m - Tn )
m/s Stmng Medium Slight Negative Positive j
$2 A
A B
E F
2to3 A
B C
E F
f 3 to 5 B
B C
D E
I S tc 6 C
C D
D D
>ft Q_
D D
D D
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2 7
4 l I 3
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- Table 2-4. Delta Temperatum Criteria Stlility Class Delta-Temperatum
(*C/100m)
A
< -1.9 B
-1.9 to -1.7 C
-1.7 to -1.5 D
-1.5 to 4)5 E
-0.5 to 1.5 F
1.5 to 4.0 G
> 4.0 4
I' s
I i
2 - 21
i
[.
Table 2-5. Solar Radiation (DayySigma-theta (Night) Stability Classification Method.!.
Nieht Day Delta Temperatum (T, T,E)( C/m)
Incoming Solar Radiation (W/m')
(m/s)
> 700 -
- 350 to 50 to 350
< 50
< -0.01
-0.01 to
>+0.01 -
l' Wind f
s2
'A A
B D
D-E F
1 2 to 3
.A-B C
-D D
E F
[
B-C D
-D D
E 3 to 5 B
S to 6 C
-C D
D D
D D
>6 c
n n
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i ai 7 n t
5
)
i m
(da 0
y
.7
)
5
/
C C C C C B B A 0
N e
9 t
5 Rad ia t
0 io
.9 n
5 C C C B B B A A
(
1 ni g
1 5
h0 C C B B B B A A 1
1 5
~
~t i
l Table 2-8. Joint fmquency table (Pement) of objectively detennined stability class versus the delta-temocratum method for the 2-10 meter tower.
Delta-Temperatum Stability Class I
l A
B C
D E
F A
4.2 0.0 0.0 0.0 0.0 0.0 B
13.9 0.6 0.5 1.3 0.5 0.2 Objectively C
7.6 1.3 1.4 4.5 1.8 0.1 Detennined D
1.3 0.4 0.9 11.8 7.5 0.1 Stability Class E
0.4 0.2 0.6 5.9 8.8 2.1 F
0.0 0.0 0.0 0.0 6.5 15.3 f
t l
Table 2-9. Joint fmquency table (Perent) of objectively detennined stability class versus the sjema-theta method for the 2-10 meter tower.
Sigma-Theta Stability Class A
B C
D E
F A
1.1 0.9 1.4 0.6 0.0 0.0 B
1.4 2.0 6.9 5.9 0.0 0.0 Objectively C
0.1 0.4 5.1 10.5 0.0 0.0 Detennined D
0.0 0.0 0.2 21.5 0.4 0.0 Stability E
0.0 0.0 0.0 13.7 3.0 1.1 Class F
0.0 0.0 0.0 10.9 7.4 3.2 Table 210. Joint fmquency table (Pement) of objectively detennined stability class versus the solar radiation (davVdelta-temneratum (nicht) method for the 2-10 meter tower.
l
\\
Solar Radiation / Delta-Tempemtum Stability Class A
B C
D E
F A
4.1 0.0 0.0 0.0 0.0 0.0 B
0.0 15.4 0.0 1.3 0.0 0.0 Objectively C
0.0 0.0 13.6 3.0 0.0 0.0 Detennined D
0.0 0.0 0.0 22.2 0.0 0.0 Stability i
Class E
0.0 0.0 0.0 0.0 18.1 0.0 F
0.0 0.0 0.0 0.0 0.0 21.8 2-3
_ --__----------__ _ __ _ _a
Table 211. Joint frequency table (Percent) of objectively detennined stability class versus the net-rrliation method for the 2-10 meter tower.
f Net Radiation Stability Class A
B C
D E
F f
l A
3.6 0.6 0.0 0.0 0.0 0.0 B
9.1 3.3 2.5 1.9 0.0 0.0 Objectively C
0.9 4.8 5.9 4.4 0.0 0.0 Detennined D
0.2 0.7 1.2 1.7 0.0 17.5 i
Stability Class E
0.0 0.0 0.0 0.0 0.0 17.4 F
0.0 0.0 0.0 0.0 0.0 21.3 l
Table 2-12. Joint frequency table (Percent) of objectively detennined stability class ver::us the solar radiation (davVnet-radiation (nicht) method for the 2-10 meter tower.
Solar Radiation / Net-Radiation Stability Class A
B C
D E
F A
3.3 0.9 0.0 0.0 0.0 0.0 B
7.4 7.0 0.0 2.4 0.0 0.0 Objectively C
0.8 9.4 0.0 5.9 0.0 0.0 Detennined D
0.1 1.5 0.2 2.0 0.0 17.5 Stability Class E
0.0 0.0 0.0 0.0 0.0 17.4 1 F 0.0 0.0 0.0 0.0 0.0 21.3 Table 2-13. Joint frequency table (Percent) of objectively detennined stability class versus the Richardson's Number method for the 2-10 mc.:t tower.
Richardson's Number Stability Class A
B C
D E
F l
A 4.2 0.0 0.0 0.0 0.0 0.0 B
15.5 0.1 0.1 0.1 0.0 1.1 Objectively C
11.8 0.4 0.5 0.1 0.0 3.8 Determined D
3.9 0.9 1.2 0.6 0.4 15.2 Stability C1 ass E
3.4 0.3 0.3 0.0 0.0 14.1 F
0.0 0.0 0.0 0.1 00 21.7 2 - 26
.os-t.
Table 2-14.:: Joint frequency table (Percent) of objectively determined stability class versus t
' the Bulk Richardson's Numher method for the 2-10 meter tower.
Bulk Richardson's Number Stability Class J
LA~
B.
.C
.D
.E
'F
'A 4.2 0.0 0.0 '
O.0 0.0' 0.0
.. 1.I' B-15.3 0.2 -
- 0.2 0.1 0.1 '
Objectively C
9.4 -
1.7 1.1 -
0.8 13 2.4 D
1.0 1.4 2.2 4.0 -
8.0 5.5 '
Detennined Stability -
Class E-2.6 0.5 0.4 ~
0.4 0.6 13.5 F
0.0 0.0 0.0 0.0 0.0 21.8
' Table 2-15. Joint fmquency table (Percent) of objectively detennined stability class versus the Siema-Theta method for 9MP at the 30 ft level.
9MP 30ft Sigma-Theta Stability Class A
B C
D E'-
F.
A 03-0.6 1.2 1.3 0.7 0.1 '
B 0.6 2.4 6.0 4.3 2.5 0.8
' Objectively C
0.2 1.9 7.5 3.2 3.1 0.9 D
0.1 13-7.5 3.6 83
- 1.2 Detennined Stability E
0.4 1.8 7.8 5.1 2.2 0.7 Clas3_
F-0.7 1.2 5.2 10.1 3.4 0.7 Table 2-16. Joint frequency table (Percent) of objectively detennined stability' class versus the Sloma-Theta method for 9MP at the 100 ft level.
9MP 100ft Sigma-Theta Stability Class A
B C
D E
F A
0.2 03 0.7 1.1 1.1 0.8 B
03 0.5 2.6 4.8 4.4
' 4.1 Objectively C
0.0 -
0.1 2.1 7.1-3.9 3.4 Detennined D
0.0 0.0 1.1 7.9 8.1 5.0 Stability Class E
0.1 0.2 1.5 9.1 4.6 2.5 F-0.2 0.2 1.1 5.5 8.7 -
5.8 m
2 - 27 F
E
Table 2-17. Joint fmquency table (Pement) of objectively detennined stability class versus the Sigma-Theta method for 9MP at the 200 ft level.
i 9MP 200ft Sigma-Theta Stability Class A
B C
D E
F A
0.2 0.2 0.4 1.1 1.1 1.2 B
0.2 0.2 0.9 4.3 5.3 5.8 I,
Objectively C
0.0 0.0 0.2 4.1 7.0 4.9 I
Detennined l
D 0.0 0.0 0.1 3.1 10.7 7.8 Stability Class E
0.1 0.0 0.3 3.1 9.4 4.7 F
0.1 0.1 0.4 2.2 7.4 10,8 Table 2-18. Joint fmquency table (Pement) of objectively detennined stability class versus the Delta-Temocratum method for 9MP between the 30 ft and 100 ft level.
9MP 30 to 100ft Delta-Temperatum Stability Class A
B C
D E
F A
3.1 0.2 0.1 0.4 0.3 0.2 l
B 9.3 1.2 0.9 3.2 1.6 0.7 Objectively C
4.7 1.3 1.5 6.6 2.3 0.3 Detennined D
7.9 1.2 1.1 8.4 3.2 0.2 Stability Class E
0.9 0.5 0.8 7.2 8.1 0.5 F
0.1 0.1 0.1 2.2 8.2 10.7 i
Table 2-19. Joint fmquency table (Pement) of objectively detennined stability class versus I
the Delta-Temnemtum method for 9MP between the 30 ft and 200 ft level.
9MP 30 to 200ft Delta-Temperatum Stability Class l
j A
B C
D E
F I
A 1.2 0.5 0.4 1.0 0.7 0.4 B
3.4 1.5 1.8 6.4 2.4 1.1 i
l Objectively C
0.9 0.8 1.2 10.2 2.9 0.5 l
Detennined D
2.9 1.6 1.9 11.5 4.0 0.1 Stability l
Class E
0.1 0.1 0.3 7.8 8.7 0.8 I
J__
0.0 0.0 0.0 2.5 7.9 11.0 2 - 28 I
j i
t, r,
l i
.y l
m Section 3.0 '
Monitor Vertical Wind Profiles -
Knowledge of' the. vertical variation of wind speed with height is imponant in studying the transport
~!
- and dispersion of air pollutants. in most instances, the venical resolution,of wind speed measurements
,y
~ are limited for physical reasons such as the extent of a vertical tower or proximity of flow l'
' obstmetions. To overcome these limitations, techniques have been developed to extrapolate wind
-[t
- speed measurements from one elevation to another, applying both physical models of fluid dynamic
' and empidcal relationships from laboratory or contmlled field experiments. ' However, there is concem over the transportability of these techniques to specific applications in the field.Uds study is
. designed to specifically investigate the appmpriateness of applying an empirical wind pmfile extrapolation technique known as the power law to operational use at nuclear power generating stations located in a coastal location. A background description of wind profile extrapolation is provided in Section 3.1 and the study objective and goal in Section 3.2. A summary' of the monitoring equipment and data analysis methodology is provided in Section 3.3, with the results of the analysis presented in Section 3.4. Conclusions and recommendations are piovided in Section 3.5.
3.1 Background
- The vertical wind profile (defined as the change in wind speed with height) is not constant in time due to surface friction effects (surface roughness), the vertical temperature profile (stability), and the natural variability of the atmosphere. There are many applications in which the change of wind speed with height is an important parameter. For instance, the concentration of a pollutant measured
- downwind from a source is found to be inversely proportional to the wind speed at the elevation of
- the release. 'Ihis effect refers to the dilution of continuously released pollutants at the point of '
emission.' In, addition, wind speed effects the plume rise and the travel time between source and l;
riceptor. Since these effects are most prominent at the point and elevation of release, measurements.
.of wind speeds at the release height ase suggested for most applications involving the prediction o
' pollutant transport and diffusion.
3.-_ 1
t
-3.1.1 Vertical Wind Profile Estimates Wind pmfiles in aa operational setting are most easily obtained by taking measumments of wind speed
- at several different elevations. !!owever, in most operational cases, only one or two measurement levels are available. In these situations, theoretical estimates of the vertical wind pmfile must be used.
'Ihe two most widely employed techniques are the Logarithmic Law:
U(z) =
in and the Power Law:
U(r),,(z,),
z U,
The difficulty with using the I; garithmic Law or the Power Law method is detennining the various variables needed to evaluate the expressions. Use of the Log Law involves knowing or estimating the -
values of the similarity parameters (u, z, and K), while the Power Law requires applying the correct exponent (P) to the surface roughness and stability conditions.
To determine which method is the most appropriaic for describing a wind profile, the first step is to find the difference which will result from usieg one ruthod as opposed to another. Figure 3-1 shows the results provided by the Power Law and the Log Law as compared to a reference height (z,) and wind speed (u,)..*Ihe comparison shows the diffemnce between the methods for two types of
" roughness" conditions (m=0.1 and m=0.3, where m=0.1 is a relative!y smooth surface and m=0.3 is a relatively rough surface).' The variable m is analogous to the power law exponent. It can be shown that 1
am
- and the Log Law can_be re-written as t
4
=1+m(in(
})
3-2 4
f i
X j.I.
and the Power Law written as Y.. (. z_ y,
1.
u, z,
Solving these equations for the two " roughness" conditions (m=0.1 and m=0.3), we obtain the curves presented in Figure 31.
If we consider a change in height one order of magnitude from the reference height, z,, and a high surface rougimess or extremely stable environment (m=0.3), the difference in the wind speed calculated between the two acthods is 15.1%. Ilowever, over smooth surfaces with neutml lapse rates (such as that commonly found in the marine boundary layer, m=0.1), the difference between metheds is much smaller, around 2.3%.
Clearly, for the marine boundary layer (onshore flow), where surfre roughness is small, the difference between the estimated wind speed profile obtained using the Log Law and tnat using the Power Law method is almost negligible.' However, over land, where tempemture profiles can be significandy gifferent than neutral and surface roughness is often high, the choice of an appropriate extrapolation method becomes more difficult. In order to avoid the difficulty involved in detennining which method is appropriate and what coefficients are conect for a given set of meteorological mnditions, site-specific measurements of the wind profiles are often recommended for applications involving dispersion of pollutants released from elevated sources.
I For most appilcations involving dispersion modeling, wind speeds at elevations above a reference height are frequently detennined using the power law exponent. As suggested above, the actual power l
law exponent can vary significantly from application to application depending on the stability of the J
atmosphere and the roughness of the surfxe over which the air is traveling. The most commonly used power law exponent is applied through the so-called "In power law" or P=0.14. This value is said to be appropriate for neutml flow over relatively flat, open terrain (Sutton,1953). Similarly, the l
United States Environmental Protection Agency (USEPA) suggests a va!ue of P=0.15 for neutral stability flow in a rural environment. Ilowever, due to the variability of siting and exposure of t
3-3 i
l-l
\\
L
E meteorological instrumentation at any given location, it is often appropriate to develop site-specific wind profile exponents.
)
3.1.2 Applications to Nuclear Facilities l
In compliance with Federal Regulation 10CFR50.47 regarding emergency planning, nuclear power generating facilities in the United States are required to have " adequate methods, systems, and equipment for assessing and monitoring actual or potential offsite consequences of a radiological emergency condition." In order to meet the meteorological aspects of this regulation, nuclear power generators must have the capability of raaking near real-time predictions of the transport and diffusion of effluent fmm their facilities. In order to make such predictions, measurements or reliable estimates of the wind speed at the height of the effluent release are necessary. Such measurements are used to detennine the dilution rate of the emission as well o the transport time to receptors downwind.
Presendy, the Nine Mile Point Nuclear Generating Station (NMP) maintains a 200 ft meteorological monitoring tower (9MP) with equipment which continuously measures wind speed at elevations of 30, 100, and 200 ft. Estimates of wind speed at higher elevations are developed by using a power law relationship which employs the 200 ft wind speed. Table 3-1 outlines the wind profile exponents which are cunently in use at NMP. The exponents differ depending upon the height tunge used to calculate them, and are a function of stability. Also shown in Table 3-1 are power law exponent values typically applied for dispersion modeling applications (USEPA,1987). 'Ihis project will provide infonnation regarding the reliability of using such power law exponents (P) as a inethod for exunpolating tower observed wind speeds to the release heights at the NMP site, as well as other, similarly localeri, nuclear generating stations.
3.2 Study Objective
~1he objective of this study is to measure wind speeds at elevations corresponding to potential release
. elevations at the Nine Mile Point Nuclear Power Station Units I and 2 and the J.A. Fitzpatrick Nuclear Station. These elevations correspond to 350,385, and 430 ft above ground level. 'Ihe measurements will be used for comparison to wind speeds predicted at the those elevations using 3-4
'I
observed wind speeds at 200 ft and a power law extrapolation technique.
3.2.1 Study Goal-The goal of this study is to determine the appropriateness of extmpolating wind speeds measured at
' the 200 ft level of the NMP 200 ft meteorological tower (9MP). This technique is currently used at NMP and other nuclear power genemting stations for estimating wind speeds at release elevations for calculations involving plume dilution and transport.
3.2.2 Potential Applications for Research De results of this research are expected to be of interest to any utilities that must perform dispersion modeling using wind speed data that is collected at elevations different from the release and/or plume elevation. %c conclusions will assist in making decisions related to the need for collecting wind speed information at release and/or plume elevations.
3.3 Approach 3.3.1 Description of Monitoring System The primary data set for evaluating the wind profile between the 9MP 200ft level and the potential release elevations was obtained with a tethersonde atmospheric profiling system.- De tethersonde system consists of a large, blimp-shaped tethered balloon, tether winch, instmment package, and a ground station for neceiving data telemetered from the instrument package. De instrument package provides measurements of air temperature, wet bulb temperature, pressure, wind speed and wind
' direction. The package is carried beneath the aerodynamic balloon which is cormected to the winch by a tether line. The ascent or descent of the balloon is controlled by releasing or retrieving line from
.the winch. The balloon has a nominal inflated volume of 110 cubic feet which provides sufficient lift l
to operate to an altitude of over 3000 ft (approx. I km). The balloon is controllable by the winch for
' wind speeds of up to approxi:aately 20 mph, above which the balloon becomes unstable. Figure 3-2 3-5
shows a schematic representation of the tediersonde system and the instmment package.
When in flight, measumments are made sequentially over a period of approximately 13 seconds and transmitted as audio tones over a 403 MHz FM transmitter. 'Ihe ground station receives the signal, decodes the audio tones, scales the values in tenns of standard units, and outputs the data reports as serial digital data. The data stream fmm the receiver is captured by a computer and stored for subsequent analysis.
Although the tethersonde instmment is capable of collecdng dry and wet bulb temperatum, the main focus for this task was data collected for tethersonde elevation and wind speed Elevation is detennined by measumment of pressure. Pressure is measured using an aneroid capsule which acts as a variable c.pacitance transducer. Calibmtion enors are of the order of 0.2 mb with somewhat larger hysteresis errors which are conected during data analysis. Tempemture and humidity corrections are employed in the elevation calculation. Wind speed is sensed by a cup anemometer mounted on top of the instmment package. It has a linear response with a starting trueshold of 2 mph. Static tests indicate a measurement enor of less than 5%.
Use of the tethersonde allowed for the direct measurement of atmospheric conditions at the heights of the release points while the main meteorological tower collected data from the 200 ft level. 'The tethersonde ground station was installed at a site adjacent to the main meteorological tower and was operated by subcontractor AWS Scientific, Inc.
3.3.2 Sampling Technique Seven test runs were pmposed, exh in different meteorological conditions as practical. This appruxh was to allow comparison of the winds in meteorological flows typical of the Nine Mile Point area.
Se flight procedum for each test consisted of positioning the tethersonde at each of the three clease heights in order to record Seinute average time periods. Concurrent Seinute average data was obtained by averaging oneminute observations from the meteorological tower. Each measumment period included a set of flights at the 200 ft level, conducted both befom and after the flights at the clease point heights in order to define a benchmark of agreement between the diffemnt measumment 3-6
u
,7 systems. In total, a minimum of eight test sets wem mquired to produce a minimum total of 84 tive4ninute avemge intemomparison values between exh release point elevation and the main meteorological tower.
j In cases when strong winds or excessive heights pmcluded the use of the tethersonde (wind speeds-greater than 20 to 25 mph), it was originally proposed that free-flight radiosondes would be substituted. Radiosondes are capable of providing comparable vertical resolution of the wind and tempenture field, but they provide only a single instantaneously measured value at any given height.
In addition, the radiosondes are manually tracked ur,ing an optical theodolite, a method which has a relatively large enur compared to the cup / vane method of measurement used by the tower and tethersonde instrumentation. Herefore, the project team concluded that comparable, statistically significant data between the main meteomlogical tower and radiosondes could not be obtained, and the attemative method was shelved.
3.3.3 Data Analysis Data used to evaluate the wind profile and resulting power law exponents employed by NMP p'ersonnel underwent several data analysis levels: data validation, separation into test specific data sets, correction for 200 ft benclunark data for each test day, comparison of exh level with 200 ft tower, calculation of observed power law exponents, and comparison of power law exponents to values currently used.
Data collected during the field experiment was validated by the tethersonde operators (AWS Scientific, Inc.). Validation of the data included inspection by a meteorologist for reasonable data values based upon conditions observed, removal of suspect data and bad data, and calibration adjustments. Data fmm the 9MP tower was provided by the opemtor, Niagara Mohawk Power Corporation, and was assumed to be r dy validated.
All data was binned into a specific test day. Calculation of 200 ft benchmarks and application of
~
conections was performed on a test specific basis. A total of eight test days were performed. Data from 9MP was extmeted from the one<ninute observations, matched to the tethersonde mas, and 3-7 f
1 u_____-_________.__._
averaged to five minute values for comparison to the tethersonde five minute everages.
Exh days collection of 200 ft tethersonde wind speed observations were compared dimcdy to the 200 ft 9MP tower observations. A mean bias and standard deviation was calculated. The bias was interpreted as the test correction for the tcmaining tethersonde observations taken during the test day, and the correction was applied to each subsequent five4ninute tethersonde average at 350,385, and 430 ft elevations. The correction was intended to adjust for test-to-test (day-today) variations in die performance and horizontal location of the tethersonde.
Elevated data from the tower was matched to the corrected tethersonde data and compared. The comparison involved calculation of a power law exponent (P) for each observation pair. The P factor was calculated using the following equation:
in(U /U,)
3 g In(r3/z )
a In order to determine the impxt of applying the 200 ft benchmark correcdon to the calculadon of P, the exponent was detennined for both uncorrected and corrected data.
'the wind speed at the elevated levels was also compared to the expected value predicted using an average power law exponent from those currently employed at NMP and outline in Table 31. The avemge P exponent employed was for a 30 to 200 ft correction and D stability class (ie. P=0.275).
Scatter plots of the predicted versus observed wind speed were produced for each release height. 'lhe scatter plots show the relative comparability of the actual and predicted wind speed and the applicability of the existing power law exponents used at die site.
1 j
3.3.4 Limitations of Study
]
Every pmetical effott was made to minimize the limitations of this study. However, limits in the I
operation of the equipment and evaluation of the data existed that wem beyond the conuol of die l
project team. First, the evaluation of measurements is limited due to the difficulty of matching the 3-8 i
i l
1 U Pt E
C tower and comparison instrumentation in time and space. Following are the significant time and space limitations to the analysis:
Every effort was made to keep the tower and tethersonde measumments within an accuracy of 30 seconds. His may be a source of error, especially in variable wind speed conditions.
Tethersonde height was maintained within 10 feet of the desired measurement elevation during each test.
Re tethersonde launch site was located approximately 200 m from the tower. This horizontal sepamtion was necessary to prevent the measurement systems from interfering with one another and to maintain a safe operating distance from the tower.
In addition to the measurement limitations, operational restrictions also limit the study as follows:
Wind speed comparisons between the tower and tethersonde measurements are limited to light or modente wind speeds (less than 20 mph) due to the operational limits' of -
the tethersonde.
Weather condition restrictions on the tethersonde system also limited the operations of the tethersonde. De system was not operated during periods of low ceiling, nestricted visibility, or precipitation.
Due to the intensive labor and resulting expense involved in operating the tethersonde system, the operational duration of the tethersonde and collection of comparative data was limited. Attempts were made to sample in a variety of stability and wind direction conditions.
We tethersonde's battery operated instmment package and telemetry transmitter limited the time the tethersonde could spend aloft during any given test period, since die battery required replacement every 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> or so of operation.
i 3.4 Data Analysis Results Data used in the analysis of wind profiles and calculation of power law exponents is provided in Appendix B. A total of eight test runs were perfonned on eight sepamte days. He test mns and counts of 5 minute averages obtained at each of the desired elevations is summarized in Table 3-2.
Limitations in the weather conditions and other duties related to the project (i.e. Task 4), limited the tests during the initial four periods, initially, only seven test days were projected. However, an enor on the part of the subcontractor collecting the tethersonde data led to a shortfall in the number of averages expected compare'd to the goal of 84 at each elevation. To conect this shortfall, a make-up I
l test day was scheduled. His xcounts for the May 10,1993 test day, as well as the significant 3-9
I number of observations taken at the 430 ft elevation on this day. It should be noted that this may bias the results for the 430 ft level when compared to the more even distdbation of observations obtained at the 200,350, and 385 ft heights.
The following sections provided a summary of the weather condidons during each test, analysis of the 200 ft benchmark data, presentation of the wind profile exponents detemiined using 9MP 200 ft data and tethersonde data at 350,385, and 430 ft, and a comparison of the observed versus predicted wind at the potendal release elevations.
3.4.1 Summary of Test Conditions ne following briefly summarizes the time of day the test runs took place, the weather condidons observed during each of the tests, and briefly any problems experienced dudng the test, 3.4.1.1 Test 1 - June 23,1992 De first test of this task took place with two tethersonde flights during the early to mid-aftemoon period of the day between 1300 and 1600 LST. Two flights were conducted during the period. Tle weather was mainly clear with wind onshore from the northwest. Wind speeds were generally below 10 mph tiuuughout the aftemoon. Stability, using the 30 ft to 200 ft delta-temperatme measured at 9MP was classified as 'A (extremely unstable) ttuuughout the aftemoon.
t 3.4.1.2 Test 2 - August 6,1992 Two flights took place on this day during the evening hours centered around sunset. The tests took place between approximately 1940 and 2240 LST. De evening was clear, with winds at flight elevation nearly paral'el to the coast from the west-southwest at 5 to 10 mph early in the test period, backing to southwest at less than 5 mph by the end of the test period. Clear sky conditions and light winds resulted in F and G stability classes thmugh the test. A land breeze developed during the test.
l appearing first at the 30 ft level of the tower early in the test. and deepening to the 200 ft level by the end of the test. His type of mesoscale phenomena can account for significant differences between tower winds and those observed at release elevations.
3 - 10 I
1
- ~. _.
3.4.1.3 Test 3 - August 24,1992 A single flight took place during the late moming between 0900 and 1100 LST. He winds wem light lium the south-southwest to southwest during the test, with speeds between 5 and 10 mph during the Grst half of die test, decreasing to less than 5 mph during the second half. fletween 1(M5 and 1100 LST, a lake breeze developed an onshore flow from the west and west-northwest. Stability dunugh most of the test was slightly unstable to neutral (C to D), until the development of the lake becze, when stability became stable (E). Like the land breeze, the lake breeze is a mesoscale phenomena which occms along the lake shore area which can account for significant differences between the tower wind speed and direction measurements and those measured at iclease eleva' ions.
3.4.1.4 Test 4 September 13,1992 As with Test 2, Test 4 took pire in the everung hours around sunset, beginning around 1830 and ending at 2000 LST. Winds wem offshore from the southeast duoughout the test, and incmased from 8 mph at the beginning of the test to near 20 at the end of the test. Due to the increasing winds and turbulent nature of the air, the test was cut shon as the tethersonde was becoming unstable in the increasing wind speeds. Stability during the test was classified as G (extremely stable). He day had been mainly clear with a lake breeze during the late moming and aftemoon, followed by a rapidly
' developing land breeze in the evening and an increasing southerly gradient wind as high pressure passed east of the area. A low level noctumal wind speed maximum is also suspected based upon the j
high mnds observed by the tethersonde and the 200 ft level of the tower, while surface winds remained relatively light. Again, these mesoscale featwes are cause for concem since they can create significant variations in wind speed and direction between the 200 ft level of the tower and the release elevations.
j 3.4.1.5 Test 5 - October 5,1992 A moderate northeasterly gradient wind flow dominated the fifth test as high pressure was nonh of the j
g j
ama. He test took place during the late moming, from 0940 to 1135 LST. Nonh-nonheast to northeast winds at 10 to 15 mph lasted through the test. Stability in the cool air flow around die high was genemlly neutral to slightly stable (classified as D or E).
3 - 11
F l
i I
i 3.4.1.6 Test 6 - October 6,1992 High pressure condnued in the vicinity of NMP during an extended day of flight marking Test 6.
Flights began before sunrise around 0515 LST, and lasted until late aftemoon (1700). A weak land breeze fmm the southeast with wind speeds fmm 5 to 10 mph dominate until mid-moming, when a weak lake breeze developed and persisted thmugh the aftemoon. Stabilities were stable during the
~
early portion of the test, then becane unstable just prior to the development of the lake breeze during the mid to late moming. 'Ihe onshore flow during the aftemoon has mainly neutrm to slighdy stable stabilities.
3.4.1.7 Test 7 - October 7,1992 liigh pressure and weak gradient allowed a lake breeze to develop dudng the seventh test day. ~nuce I
flights were conducted during the period fmm 0910 until 1535 LST, with the lake breeze developing j
during the first flight. By 1100, the onshort lake breeze was well established, but wind speed remained quite light, remaining around 5 mph or less throughout the remainder of the test. Stability was extremely unstable (A) early in the first test as the !ake breeze developed, then becane 'neutml or slightly stable (D and E) once the onshore flow of the lake breeze was established. Significant variability occurred between the 200 ft tower level and the test elevations during the onset period of 4
the lake breeze.
3.4.1.8 Test 8 - May 10,1993 4
[
Weak high pressure with variable oveirast conditions dominated the eighth and final test day. Flights i
wue conducted between 0800 to 1730 LST, with winds generally 5 to 10 mph fmm the west southwest throughout the test day. The only exception was a period of very light and variable winds which occurred at the 200 ft level of the tower during the early aftemoon. However, wind speeds rernained between 5 and 8 mph at the 430 ft elevation dudng this time period. It is not clear what l
t caused the different wind speed conditions, however the tethersonde opemtors confirmed the j
tethersonde data by observing the motions of the tethersonde balloon and the tether wire. As will be I
(
shown, this event IM to significant differences in the P exponent calculations for the 430 ft level during this test.
3 - 12
p 3.4.2 Analysis of the 200 ft Benchmark Data Figure 3 2 shows a scatter plot of the tower measured versus the tethersonde measured wind speed at 200 ft. %is comparison was perfomied at the beginning and end of exh test in order to develop a benchmark correction to be applied to the tethersonde observations (except Test 4 where high wind speeds resulted in a comparison only at the start of the flight). This benchmark was intended to take into account any changes in calibration between the instmmentation, as well as changes in the horizontal location of the tethersonde due to flight in varying wind directions. For each test, the 5-minute average 200 ft tower wind speed was compared to the 5-minute average 200 ft tethersonde wind speed, and an average bias calculated (9MP wind speed - Tethersonde wind speed).o De average bias was then added to the tethersonde wind speed for all observations at attemate elevations during the test in an attempt to correct the tethersonde data for instmmentation error, he average difference between the observed 200 ft wind speed on the 9MP tower and the tethersonde (benchmark conection) for exh test is summarized in Table 3-3. As can be seen from Table 3-3 and Figure 3-2, the tethersonde tended to measure wind speeds less than those observed at the 200 ft level of the 9MP tower. Thus, in all but Test 2 (8/6/93), the tethersonde observed winds were increased for comparison at other elevations.
An independent analysis of the 200 ft tethersonde and tower data indicated that the wind speeds observed by the tethersonde and the tower are likely not the same (Caiazza,1993). Els conclusion was based upon conducting a student's t distribution of the 200 ft wind speed data, which showed that the probability of the tethersonde-tower wind speed difference being due to random fluctuations (as is assumed in this analysis) is less than 0.001. However, in ortler to make the most of the data, the comparison at attemative levels was carried out using the described procedure. Hopefully, the comparison can still provide a useful indication of whether or not adjustment of instantaneous 200 ft measurement to altemative heights using a power law function is justified.
3.4.3 Observed Wind Profile Exponents ne caletdation of wind profile exponents for each test elevation and each test are shown in Appendix 3 - 13 l
l w
B and summarized for elevations 350,385, and 430 ft in Tables 34 through 3-6, respectively. Tables i
34 through 3-6 show variability in the average wind speed profile exponent when compared test-to-test. Power law exponents averaged between 0.07 and 0.05 for 350 and 385 ft, respectively, and increased to 0.40 for 430 ft. Individual test values ranged between -0.38 to 0.68. Note that a negative power law exponent is indicative of wind speed decrcasing with height. Inspection of the individual power law exponents calculated for exh five minute average as shown in Appendix B indicates even more dramatic variability, and highlights that the use of the power law exponent on an individual observation basis is not necessarily appropriate.
Care should be taken in comparing the power law exponents obtained for the various test elevations.
While the tendency of the power law correction was similar within each test, the eight test average values differ significantly between 350 and 385 ft (0.05 and 0.07, respectively) and that obtained for 430 ft elevation (0.40). This difference is believed to be a result of the different sample distributions obtained between the elevations. For example, over half of the 430 ft samples were collected during a single test (5/10/93), while the 350 and 385 ft samples had a more even distribution.
It is interesting to note that the average values behave in a way similar to that expected from theory.
For instance, power law exponents obtained for the 350 ft and 385 ft elevations over a variety of stability classes and wind directions are slightly less than the mean value of 0.14 frequently suggested O'anofsky and Dutton,1984). Also, a value of 0.40 at 430 ft from samples collected during primarily stable conditions is also similar to expected values (USEPA,1987). Also, the 350 ft and 385 ft values are similar to values outlined by Segal and Pielke (1988), where a power law exponent of 0.07 is suggested as reasonable in neutral stable marine environments.
Based upon'this analysis, it is reasonable to conclude that, under light to moderate wind speed conditions, at a location with important mesoscale features, application of the wind speed profile on a cese specific basis in not necessarily appmpriate. However, on an average wind speed basis, the power law exponent appears to provide a reasonable estimate of winds speeds at elevations above the reference elevation.
i f
I i
l I
3 - 14 i
1 l
t l
l
p f
k l
3 3.4.4 Observed Wind Profiles Compared to Predicted 4.;
r l'
' h;' Using the observed 200 ft wind speed for the 9MP tower and the established wind pmfile exponents r
E!
Y for the tower as outlined above and in Table 3-1, a predicted wind speed was calculated at each of the y
vied test elevations and compared to the tethersonde observed wind speeds. Since stability was variable l h during testing, an " average" wind profile exponent was used as a simplified approach to detennining I
the predicted wind speed at the test elevations. The pmfile exponent selected was 0.275, which
/
corresponds to the exponent for the 30 to 200 ft levels of the tower during a D stability. 'This
[
exponent was applied to the 200 ft elevation (reference) to calculate the expected (predicted) value at f
each of the release elevations.
a 9
N Scatter plots of the predicted versus observed wind speed at each of the test elevations for each y
9 sample are provided in i~igures 3-4 through 3-6. As can be seen fmm the plots, them is a fair amount of scatter, particularly with increasing height, amplifying the difficulty in applying the power law on a case-specific basis rather than an average basis. In general, the wind speeds calculated fmm the cunent power law exponent values (predicted) am higher than the observed. Thus, the cunent exponents in use at NMP rnay tend to over pmdict wind speeds at release elevation. Also, the application of the power law becomes even less mliable as the height for which the wind speed is being calculated differs from the reference height. 3.5 Conclusions and Recommendations Methods for extrapolating observed wind speeds to elevations different from the observed have been developed using both physical and empirical models. At NMP, a power law extrapolation technique is employed using a set of site-specific power law exponents to extrapolate wind speeds from the 200 ft level of the meteorological tower (9MP) to potential effluent release heights. In order to detennine the appropriateness of applying this extmpolation technique at NMP, wind speed measumments were taken at 350,385, and 430 ft using a tethersonde atmospheric profiling system, and concurrent measurements collected from the 9MP tower at the 200 ft elevation. A comparison was conducted between the 200 ft measurement level and the release elevations, from which the following conclusions are made: 3 - 15 C
Based upon the ilmited data set collected during this study, the current power law e exponents employed to correct 200 ft wind speed to release heights at 350,385 and j 430 ft tend to over predict the actual wind speed. His is particularly significant since the power law exponents can become quite large for both stable and extremely unstable conditions, resulting in even higher predicted wind speeds than those l presented in Figures 3-4 through 3-6. He application of a wind profile exponent becomes less reliable as the difference between the reference and predicted elevations increases. ~ Elevated wind speeds calculated using established wind power law exponents show poor correlation to observed wind speeds on a case-by<ase basis. liowever, applied to wind speeds averaged over a long period under a variety of meteorological conditions, power law exponents perfonn well. Re occurrence of mesoscale phenomena such as lake and land breezes, and noctumal low-level wind speed maximums are problematic for the application of wind profile exponents. Due to the large variation in the vertical distribution of meteorological parameters found with these phenomena, simpie, empirical relationships such as the power law fall to adequately describe the complexity of the physical processes involved. Based upon the conclusions, the following recommendations are made: Due to the limited nature of this study and the discrepancy between 200 ft tethersonde and 200 ft tower measuremen's, further measurements using a combination of tower, tethersonde and remote sensing instruments is recommended on a regular basis (e.g. annually). Changes in the surrounding surface roughness on a seasonal basis'should be measured. Routine measurement of uind at release elevations is recommended by either employing a tall meteorological tower or reliable remote sensing system, depending on the data recovery objective required. Be pmetice of using established wind pmfile exponents to calculate wind speed at release elevation on an observation specific basis should be reconsidered. Such use can result in large errors between the predicted and observed wind speed. Consideration should be given to using observations of wind speed at the desired elevation as a first option, measurements of 200 ft wind as a second option, and extrapolated wind speed estimates third. Use of established wind profile exponents to deteMne average winds at release elevations is most likely appropriate, however the exponents should be further refin-d with measurements between the tower and release elevations rather than the tower alone. 3 - 16 J
g, R 3.6 References Caiana, R. ' 1993. Tower and Tethersonde Wind Speed Comparison. Memo to Tom Galletta (NMPC) and Civis Bedford (Galson), October 8,1994. NRC,1980. Proposed Revision 1* to the Regulatory Guide 1.23: Meteorological Programs in Support of Nuclear Power Plants. US. Nuclear Regulatory Commission, Washington, D.C. Panofsky, H.A. and J.A. Dutton,1984. Atmospheric Turbulence. John Wiley and Sons New York. ~ Segal, M. and R.A. Pielke,1988. The Extrapolation of Vertical Profiles of Wind Speed within the - Marine Atmospheric Surface Layer Using the p Fonnula. Monthly Weather Review,27,174-181. USEPA,1987. On. site Meteorological Program Guidance for Regulatory Modeling Applications. US. Environmental Protection Agency, Research Triangle Park, N.C. 4 'e 3 - 17 L
) r l 4 l Comparison of Logarithmic and Power Law Wind Profile Solutions a j 10 i I.* / I f.* / ll / O / I /..
- m=0.3
/ / _.=' i I LOG m N j A ~ N 11 /1 m j7 /I B I A' I j rn-0.1 l l l .1 0 1 2 i U/Ur Figure 31. Plots of differences in estimating the wind profile using two different methods. 3 - 18
l j \\ TETHERSONDE UGHT f'. % CHOPPER % uAowTc/ COMPASS ~ DRY '{ N I ENCODER WET "k SATTERY g FAN COMPARTMENT PF TRANSMITTER WATER RESERVOIR ANTENNA ANERCND CAPSULE 4> v i Figure 3-2. Schematic of the tethersonde boundary layer profiling system showing the balloon, winch, ground station, and attached instmment package Oeft); and the instmment package parts (right). i 3 - 19 4 W_.
. 7,m.naa:a cu- 'f. Tethersonde 200 ft Wind Speed (mpt0.. T -h 4. C. y 4. ? 7 P 'g 'g g-2 g Q 5 5 5 5 5 ~ ,,g --t 4 3._...t - a - -i 5 \\ DJ 3 8 -- \\ t, e ? !_~= + e b n E q9 8 m DJ e 8 9 a m\\ 9 Y 7 c3 e g dg a & E o so a =s w,E = '- 8, CA .k.. 'O
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1 i 1 1 i 2 o 2 4 6 8 0 4 6 s 0 O .! i + 1 rlit1I< ./ 2 ~. a,/ m 4 ms E 9 a m M g P e 3 ,e 8 6 5 a E f g t E
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P d E' m i r c e I t d e d ci 8 t v e s d m T 3 e 8 ,8 hF t 3 5 n e f sa rgi 2 t 2 s u W1 o r i 0 a n e n d 3 d e - a 5 S O p b e s e e d rv ( 1 = e m2 d p 3 h 8 s 5 f u t m W 1 a in 4 d S p s eed 1 a 6 E ~ 1 E " 8 2 0 a l I-l
8 1 = 6 1 dee B p S 4 d l 1 n i a W tf e 0 ) 3 h 4 a p d 2 m e 1 ( vr de e a e s O p b S 6 d - e n 3 d i 0 e n l 1 W r o g u s t g r f i e 0 Fh a 3 te s 4 T E l de s m t v c E l l 8 id de t s . a e ic r me g P d er aa P a t f m m 3 5 l 6 0 4 8 P M m 9 m
- 4
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l 0 0 8 6 4 2 0 8 6 4 2 0 2 1 1 1 1 1 ,5E58o{ $eeQ@8=s$. 1ill
l t Table 3-1 Established Power Law P-factor Values USEPA' 9MP Site-SpeciDe P-values 2 Stability 10 m Reference 30 ft to 100 ft 30 ft to 200 ft 100 ft to 200 ft A 0.07 0.281 0.343 0.264 B 0.07 0.2 M 0.241 0.255 C 0.10 0.289 0.212 0.223, D 0.15 0.313 0.275 0.259 E 0.35- -0.486' O.431 0.387 .F 0.55 0.613 0.561 0.484 G 0.707 0.564 0.493 L i Values commonly used in regulatory modeling applications (USEPA,1987). 8 Values currently in use at NMP (EIA.1984). 5 G stability class not employed by EPA. Assumed same as F stability class. p. 3 - 24
v. Table 3 2 Summary of Field Monitoring Data Elevation Dale' 200 ft 350 ft ' 385 ft 430 ft 6/23/92 4 8 10 4 8/6/92-7 7 8 4 8/24/92 5 6 6 3 9/13/92 3 3 6 3 10/5/92 6 6 6 3-10/6/92 30 30 30 15 10/7/92 16 16 16 8 5/10/93 16 16 16 48 Total 87 92 98 88 Goal 84 84 84 84 Percent of Goal 1(M% 110 % 117 % 105 % g 3 - 25 E
? Table 3 3. Summary of measured differences between 9MP and tethersonde 200 ft elevation. Date Stability 9MP Tethersonde Average St. Dev.of (30 to 200 h Average Average Difference Difference Delta T) (200 ft) (2fW) h) 6/23/92 A 6.75 6.44 0.31 1.41 8/6/92 F/G 5.91 6.47 -0.56 0.57 8/24/92 D (Variable) 6.27 5,50 0.77 0.45 9/13/92 F/G 9.60 8.20 1.40 0.I 4 10/5/92 A 14.20 13.21 0.99 1.65 10/6/92 A/C/D/F 7.29 6.39 0.90 0.40 10/7/92 B 4.78 3.94 0.84 0.63 5/10/93 F 7.11 6.04 1.07 0.42 Average (all 7.11 6.32 0.79 0.78 i+servaums) Table 3 4. Summary of calculated power law coefficients (P) for 350 ft. Date Stability Avemge P at St. Dev. Average P at St. Dev. (30 to 200 ft 350 ft (Uncorrected) 350 ft (Corrected) Delta-T) (Uncorrected) (Corrected) 6/23/92 A 0.08 0.21 0.18 0.20 8/6/92 F/G -0.09 0.6 -0.30 0.74 8/24/92 D (Variable) -0.40 0.34 -0.11 0.24 9/13/92 F/G -0.22 0.02 0.02 0.03 l 10/5/92 A -0.11 0.09 0.04 0.10 10/6/92 A/C/D/F -0.24 0.24 0.03 0.22 10/7/92 B -0.78 ('.32 -0.28 0.24 f /10/93 F 0.43 0.81 0.68 0.83 Average tall -0.18 0.57 0.07 0.57 Olnervaamsi 3 26
- ,#.w.
w_ f
Table 3-5. Summary of calculated power law coefficients (P) for 385 ft. I Date Stability Average P at St. Dev, Average P at St. Dev. I (30 to 2to it .$ 85 li (l'ncorrected) 385 ft ICurrected) I Delta-T) (Uncorrected) (Corrected) 6/23/92 A 0.20 0.09 0.28 0.09 8/6/92 F/G 0.27 0.24 0.12 0.23 8/24/92 D (V: triable) -0.25 0.16 -0.02 0.15 9/13/92 F/G -0.08 0.16 0.09 0.13 10/5/92 A U.00 0.14 0.12 0.14 10/6/92 A/C/D/F -0.20 0.26 0.04 0.23 10/7/92 B -0.87 0.64 -0.38 0.46 j 5/10/93 F 0.08 0.39 0.30 0.36 -0.17 0.49 0.05 0.35 Average tall duervatims) Table 3 6. Summary of calculated power law coefficients (P) for 430 ft. Date Stability Average P at St. Dev. Average P at St. Dev. (30 to 200 ft 430 ft (Uncorrected) 430 ft (Corrected) Delta T) (Uncorrected) (Corrected) 6/23/92 A 0.19 0.14 0.25 0.13 8/6/92 F/G 0.15 0.19 0.03 0.16 8/24/92 D (Variable) -0.17 0.05 -0.01 0.06 9/13/92 F/G -0.09 0.04 0.07 0.04 10/5/92 A 0.22 0.20 0.33 0.19 10/6/92 A/C/D/F 0.23 0.41 0.38 0.38 g 10/7/92 B -0.71 0.31 -0.36 0.2I l l: 5/10/93 F 0.47 0.84 0.65 0.85 i l 0.24 0.73 0.40 0.73 Average tall seservaticus) 3 - 27 L. I'
.t.'. Section 4.0 Detailed Regime Measurements ne coastal transition between land and water complicat l cation, including where power li conditions of the shoreline zone, Bds is tme at any shore ne of Lake Ontario s generating facilities are located on the southeaster shore o d Oswego Steam Station, the Power Corporation's Nine Mile Point Nuclear Power Station (NMP) an d Kintigh Station operated Ginna Nuclear Station (Ginna) operated by Rochester Gas and Elec h by New. York State Elecuic and Gas. In order to learn mom about b occurring in the coastal tmnsition zone, a series of intensive o servrchers a vicinity of NMP and Ginna to collect data for use by resea logy as it relates to the transport impmve conceptual and numerical models of the coastal zone mete and dispersion of pollutants. bi f background descripdon %is Section presents the results of the intensive monitoring i of the meteorological phenomena measured dur ng t onitoring approach are provided in d goal presented in Section 4.2. Descripdons of the equipment an l - Secdon 43, with the intensive observation resu ts r e e conclusions and recommendations summaries are presented in Appendix C. Secdon 4.5 oudines som resulting from the collection of the detailed measurements. 4.1 Background - based upon air flow over flat, uniform, d Many meteorological theories, observations, and metho s ared frictional cha and homogeneous terrain. The abrupt changes in terrain an ause marked departures differential heat and moisture fluxes encountered at d homogeneous terrain. fmm condidons predicted by methods which assume flow over u h rp temperature contrasts can Since water is slow to heat or cool with respect to adjacent land h exist between air over land and over nearby water. During t e su 4-1 f C
become very warm and induce atmospheric instability in the overlying air. Offshore, the rela cool lake water produces a stable environment which is not conducive to the thermal and con instability over the land. During winter, the situation is reversed with the relatively warm the lake inducing instability over the water, and the snow covered land remaining relatively co I stable. In a similar way, diumal cycles create differences between the airmasses overlying water and over land. At night, the land cools quickly, creating a relauvely stable air mass compared or negligible cooling of air overlying the water, which can become reladvely unstable. when solar insolation is near a minimum and snow frequently covers the ground, the incid warm unstable air over the water and relatively cool, stable air over the land can persist eve daylight. In order to model the behavior of a plume released into the atmosphere, the characteristic prevailing altmass must be understood. The atmosphere in a shoreline environmen characteristics which can significantly deviate from predictions based on idealized conditio objective of this task is to funher assess atmospheric characteristics in a shoreline env 4.1.1 Important Meteorological Regimes Over Eastern Lake Ontario To funher the understanding of the complicated meteorological conditions of the coasta i task focused on the collection of detailed measurement during four different metcomlogi on-shore flow, lake breeze, land breeze, and low level jet (LIJ). The following briefly d of the four target regimes, and the imponance of the condition to the assessment of polluta and dispersion. 4.1.1.1 On-shore Flow A detailed description of the implications of on-shore flow to the transpon and diffusion pollutants is provided in Section 1.0 of this report. In summary, the flow of a imponant since the air masses overlying each differ, having obtained attributes land or water surface. For instance, on a sunny spring or summer day, the air flowing 4-2 I j
the lake will tend to be cooler, more humid, and more stah'e than the air over the land surface being warmed by the sun. As air moves fmm one surface to anomer (i.e. water to land), it is modified at the bottom, taking on the characteristics typical of air resident over the new surface. The layer of modified air near the surface is referred to as an Intemal Boundary Layer (IBL) because it gmws within another boundary layer associated with the approach flow or unmodified air. When an IBL develops as a result of cooler, stable lake air moving over warmer, unstable land air, the layer near the surface is referred to as a Thermal Intemal Boundary Layer or TIBL. Since the vertical distribution of stability is important in the identification of TIBLs, monitoring of the vertical temperatum gradient is most important in observing this phenomena. The most significant result of the existence of an IBL is a vertical variation in the stability which can have a profound effect on the manner in which pollutants are dispersed downwind from a source. Pollutants initially released into the stable layer may eventually intersect the boundary between the stable layer and deepening unstable surface layer. When this xcurs, pollutants can be rapidly mixed down to the surface resulting in elevated pollutant concenzations. Knowsedge of the existence and elevation of the TIBL with respect to the elevation of stack emission plumes is vital in describing dispersion processes in a shoreline region. 4.1.1.2 Lake Breeze 'The lake breeze is a raesoscale circulation caused by the differential heating of the land and water areas in the region during daylight hours. The land areas absorb greater amounts of incoming solar radiation as compamd to the water areas. As the day progresses the land areas heat more rapidly than the adjrent waters. The difference in temperature creates a pressme gradient between the land and water, producing a wind which flows from the water towards the land. Often with this situation the formation of a retum flow from the land towards the lake will appear at higher altitudes. In the ideal lake breeze, the elevated retum flow branch is directed 180 degrees opposing to the surface flow. This large vertical variation on wind direction found in the lake breeze can make it difficult to predict the 'ransport direction of elevated pollutant releases. i 'Ihe classic lake breeze develops during the late moming and will continue until early evening, when 4-3 l l
the cooling of the land mass destroys the driving force of the lake breeze. The pmdiction of the ortset, stength, and duration of the lake breeze is complicated by the lake breeze dependance on a number of meteorological factors. Lake bmezes are highly depen %)t on the gradient wind direction and speed (synoptic scale), magnitude and sign of the lake / land tempratum difference, and solar insolation. Other factors have also been noted as influencing sea breezes such as the surface frictional difference between the lake and land, depth and strength of synoptic scale inversions, and terrain. 4.1.13 Land Breeze Like the lake breeze, the land breeze results from a pressure gradient caused by diffuences in lake and land tempemtum. However, rathr than resulting from diffemntial heatme during the day, the land breeze is a result of differenti>' shng between the land and the water at night. The land mass cools quickly following sunset while the water, with its higher heat capacity changes in temperatum only marginally between night and day. During evenings when the land cools to a temperature below the lake, a pressure gradient develops between the lake and the land which drives a flow of air from the land toward the lake. Land breezes tend to develop under stabilizing radiation inversions over the land, and therefom tend to be shallower than lake bmezes. This makes the land breeze particularly important since large differences between surface and elevated wind conditions can result. Land breezes are more common than lake breezes in the study area. They are often enhanced by drainage winds which flow down toward the lake frum the elevated terrain sunnunding the study area. Drainage winds result when cooling of the land surface causes the air closest to the ground to cool, and, being more dense, flow from higher elevation to lower elevation. 4.1.1.4 Low L.evel Jet (Noctumal Wind Maximum) It has been frequently observed that under certain meteorological waditions, extremely high winds can develop in thin layers above the surface. This phenomenon, which is most common at night, has been observed at Nine Mile Point (NMP) by the 200 ft meteorological tower (9MP) and doppler sodar. Referred to locally as the low level jet (LLJ), the phenomenon is more appropriately described as a noctumal boondary layer wind speed maximum since the use of the term jet implies a featum of limited horizontal extent. The noctumal wind speed maximum is caused by an ageostruphic adjustment to the gradient resulting from decoupling of the surface wind due to the noctumal, surface-based 4-4
-y f tf i,p ,h !.hl-L radiation inversion. The wind speed maximum has been observed at relatively low elevations (as low as 100 ft), and is strongly correlated to the height of the surface-based radiation inversion. The existence of the LLJ has implications fc,r the transport and dilution of pollutant plumes. The appearance of the LLJ at elevations above which, routine measwement are takers, yet at potential plume heights,is also of concem. Measmements at nuclear frilities are intended to be representative of plume release height conditions. ~ 4.1.2 Applications to Nuclear Facilities The metcomlogical program at Nine Mile Point Nuclear Power S:ation is subject to regulations and guidance as stipulated by NRC NUREG/CR-0936 and Safety Guide 1.23 Revision 1*. Meteomlogical data coliccted in support of the meteorological piograms are used for short-and long-term dose calculations, and emergency response plume tmjectory and arrival times. Regulations and guidance make specific statements regarding the need, location, availability, quality, and type of meteorological measurements. NRC NUREG/CR-0936 identifies the following problem areas for meteorological progmms at coastal frilities: . Coastal intemal boundary layers . Tower location
- Instrument height
- Atmosphede stability classification l
- Plume meander
- Diffusion calculations This study will investigate further the first four problem areas identified by NRC and produce l
recommendations and justifications addressing each problem. 4.2 Study Objective 1 l The objective of this task is two-fold: 4-5 k
( Detennine the similarity between Ginna and Nine Mile Point during typical on-shore l flow conditions. Obtain detailed measumments of several types of lake-induced flow regimes. l The primary concem for the fonner is whether the boundary layer height equation developed a of Task I is appropriate for use at Ginna Station located approximately 100 km west of Nine M Point. The objective of the latter is to provide a data base of regime specific detailed case stud ongoing mesoscale model development and validation. 4.2.1 Study Goal The goal of this study was to collect meteorological data with high spacial and temporal during specific meteorological events. The p mose of the data collected was to provide re with detailed infonnation for the development and validation of models used to predict dispersion meteorology in shoreline environments. 4.2.2 Potential Applications for Research Any utility with a source of atmospheric pollution !ccated in a coastal or shoreline area may potentially benefit from improved understanding of the dispersion meteorology in the co Detailed observations of the targeted phenomena wili adow ruearchers to develop improved m better predict the meteorological parameters which are imponant to tile transport and d pollutants in regions experiencing complex meteorological flows. The detailed stud beyond that typically available using routine measuremems. ~ Bis research provides information of interest to utilities wishing to investigate the potentia predicting the dispersion meteorology associated with the following concems: . Lake and land breezes, e Venical variations in stability associated with TIBLs, and . Venical wind profile variations associated with low level jets. 4-6 i s
iL .w. 4.3 Approach 43.I' Description of Monitoring Systems Reliable methods for the continuous measurements of tne atmospheric boundary layer have only recently become a reality. Below, a summary of boundary layer measurement methods is provided Each method has specific advantages and disadvantages that are imponant considerations when designing a boundary layer measurement progmm. Additional information on some of the measurement techniques is provided in Section 5.0 of this repon. 43.1.1 Meteorological Tower Metcomlogical towers have been the primary method of collecting meteorological measurements f many years Instmmentation such as anemometers, wind vanes, thermometers, dew cells, and o standard meteorological instmmentation are installed on the tower at fixed elevations. Tall towers can have multiple measurement levels which allow determination of the venical gradients of pammeters such as wind and temperature. In addition, certain thermal and momentum flux parameters can be calculated using measurements at multiple elevations. In general, the tower method of boundary layer measumment is quite reliable and mgged. 'Ihere a few operational limits on the equipment other than weather extmmes. However, towers suffer from several basic limitations. For exanple, meteorological towers are limited in practical height; towers higbar than seveml tens of meters must be very substantial stmetures and erection of such can h i rather extreme costs. Because of height limitations, meteorological towers may not be capable of sampling desired phenomena such as the lake breeze retum flow. In addition, fixed measurement heights can limit the venical resolution of observations, and phenomena such as the noctumal je not be observed. Finally,in cases where spatially varying meteorological phenomena are ofinterest, such as the TIBL, multiple tall towers would be needed, a genemlly undesirable if not unsightly requirement. l-43.1.2 Tethersonde The tethersonde system consists of a large tethered balloon, winch, instmment package, and a groun 4-7 N
l { station for receiving telemetered data. He instmment pxkage provides measumments of air 1 tempemtum, wet bulb temperature, pressure, wind speed and wind direction. De p beneath the aerodynamic balloon which is connected to the winch by a tether line. He ascent or descent of the balloon is controlled by releasing or mtrieving liae fmm the winch. De balloon nominal inflated volume of 110 cubic feet which provides sufficient lift to operate to an altitu over 3000 ft (approx. I km). He balloon is controllable by the winch for wind speeds of u 25 mph, above which the balloon becomes unstable. When in flight, measurements are made sequentially over a period of approximately transmitted as audio tones over a 403 MHz FM transmitter. The ground station receives decodes the audio tones, scales the values in temis of standard units, and outputs the data rep serial digital data. 'Ihe data strean is captumd by a small computer and stomd for subsequ analysis. Dry and wet bulb temperature are sensed by linear thennistors housed in a mdia provide the required ventilation for accumte wet bulb measumments. Combined linearity errors of the sensors are less than 0.5 F with dynamic response limited by se constants of 15-20 seconds. Pressure is measured using an anemid capsule which acts capacitance transducer. Calibration errors are of the order of 0.2 mb with some crrors which are corrected during data analysis. Wind speed is sensed by a cup anemo on top of the instmment package. It has a linear response with a staning threshol tests indicate a measurement error of less than 5%. Wind direction is sensed using a mag compass to record the balloon orientation. Due to its aerodynamic shge, me balloo wind vane and remains pointed into the local wind direction. We accuracy of the system is approximately 5 degrees. Due to the balloon's large size, the damped response of relatively slow, limiting its response to the average wind direction. 4.3.1.3 Radiosonde The radiosonde system consists of a 30 g latex balloon and an attached instrument pa which, like the tethersonde, measures air temperature, wet bulb temperature, and pressme 4-8 l d'
.m Airsonde has a unique helicoid propeller-shaped housing consisting of lightweight, molded polystym which mquires no parachute for free fall. Aspiration of the air and wet bulb temperature sensors is produced by the Airsonde's rotation. The sensor accuracy and response specifications are co to those for the Tethersonde instmment prkage. Wind speed and direction are detemiined by tracking the balloon with an optical theodolite. He theodolite provides measurements of azimuth a elevation angles from which balloon wind speed and direction can be calculated. The Airsonde can be teleased during any weather conditions and can :each altitudes of over 30,000 f Its tansmitter range is over 60 miles. An FM transmitter telemeters data to the same ground station used by the tethersonde system. He Airsonde sampling rate is every 5-6 seconds. Radiosondes have the general limitation of having considerably lower resolution in the boundary layer due the rate of ascent and the method of wind calculations. 4.3.1.4 Monostatic Acoustic Sounder Acoustic sounding equipment is based upon the principle that a volume of air scatters incident xoustic energy. Scattering is due to wind speed and temperature discontinuities in the sampled ) volume of air. Most of the scattering occurs in the direction of propagation, but a small percentage the energy is scattered back to the source. An acoustic sounder transmits a stmng acoustic pu (typically around 100 watts) venically into the atmosphere and listens for that portion of the transmitted pulse that is scattered back to the transmitter. The monostatic sounder uses the same acoustic driver to both transmit and receive the signal with a single antenna pointed venically. Reoretical equations which relate the anount of retum signal to the velocity and thermal structure functions have been de, eloped. He existence of a temperatum gradient and small-scale tuttulence c:cate local instantaneous temperatum differences greater than the mean venical temperature gradie - A strong retum signal can be produced either by an unstable tempemture gradient and little w (convective boundary layer) or with a stable potential temperature gradient and large wind shear (stabie boundary layer). As a result, qualitative atmospheric stability and temperature profile develeped. Rus the monestatic acoustic sounder can be used to sample the boundary betwe i and non<narine air dudng on-shore flow. i 49 l L~
Monostatic sounders can produce both facsimile and digital outputs of signal strength for analysis. The fxsimile output is essentially a strip chart recording of the strength of return signal versus he for each acoustic pulse. Dark shading indicates strong signal return while light shading indicates weak. Often, stmng retums are associated with boundaries, such as the boundary between modifie surface air in a TIBL and unmodified air above the TIBL in on-shore flow. In this way, the heig such raixing layers can be detennined. Backscatter intensity data obtained using a monostat is converted from an analog signal to digital representation and stored in a computer for each o specified set of range gates or height increments. In addition to the qualitative results, one strength of sounders is their ability to detect shifts in the frequency of the transmitted acoustic pulse. Frequency shifts are caused by the doppl directly proportional to the speed of an air parcel moving away from or towards the trans this way, vertical velocity (W) and standard deviaticr. of vertical velocity (oW) can be calc each of the range gates. Atmospheric stability can be classified according to cW. l Acoustic sounders can reach heights as great as 1000 Teters, depending on the atmospheric conditions. However, this range is often limited in high winds, precipitation, and high ambientj level environments. In addition, fixed echo sourecs such as buildings and tres must also be a De limitations in siting acoustic equipment are numerous, and all must he taken into xcount wh determining an appropriate location for the system. 43.1.5 Doppler Acoustic Sounder ne doppler acoustic sounder is the same in tenns of theory and method of operation as the monostatic sounder, except that it is capable of measuring the three dimen.acoal wind profile. T systems are also known as SODARs (Sound Detection and Ranging). SODARs ach measurements using a combination of three antennas, one vertically pointing, and two pointing at angle from the vertical and 90 to each other. With this configuration, and the calculat velocity along the axis of each antenna, simple trigonometry allows the determination of the dimensional wind. As with the monostatic sounding system, siting of the equipment it vital. In addition, the range 4 - 10 ) u-----___________________
M J . sounders is limited during high winds due to the advection of signal out of the sampling volume. 43.1.6 Micmwave Pn> filer Microwave profilers are similar to doppler sodars except they rely upon the scattering of microwave energy to measure the duce wind components. This relatively new technology eliminates some of the siting and wind speed limitations of acoustic systems since they operate in a much higher wavelength range. Like the SODAR, the profiler can measum the thme diniensional wind profile by directing its signal in a similar manner, either through phasing of the antenna pulse or by physically tilting the antenna. Two types of profilers are presently under development. He most widely used and tested opemted at '404 MHz. This system can measum the tluce venical wind components fmm approximately I km above the surface to approximately 10 km. The low resolution near the surface of the 4W MHz system has limited its applicability to the problem of boundary layer measurements. The second, newer type of micmwave profiler shows potential for making boundary layer measurements. The new system operates at 915 MHz, and appears to be capable of measudng the duce dimensional wind as. Iow as sevemt hundred meters at a higher range gate resolution than the 4M MHz system. This makes the 915 MHz profiler attractive for boundary layer applications. In addition, the 404 MHz system has extremely limited range in cold, dry air. De 915 Mhz systems appear to be less limited by this condition. 43.1.7 RASS - De Radio Acoustic Sounding System (RASS)is another emerging technology that may be applied to measudng the atmospheric boundary layer. De RASS uses both the acoustic and microwave profiling technologies. By combining the two techniques, and providing for additional signal processing, the venical temperature profile can be determined. This is accomplished by essentially making use of the temperature dependence of the speed of sound. Microwaves from a profiler am " bounced" off the acoustic energy waves produced by the sodar, and the change in speed of the wave detennined. This speed change is, in tum, used to determine temperatum in each of the specified range gates. In general, the technique shows promise for boundary layer measurements of temperature, although the resolution is still too coarse to allow detailed observations of the TIBL and some inversions. 4 - 11 i l r
4.3.2 Sampling Technique The objective of this task is two-fold: 1) to detemiine the similarity between Ginna and Nine Mile Point dt, ring typical on-shom flow conditions, and 2) to obtain detailed measurements of seveml types l of lake-induced flow regimes. Rese objectives were addressed by perfomiing two subtasks as described bt. low. 43.2.1 Subtask 1 - Simultaneous Soundings at Ginna and NMP A tethersonde/ rad:osonde station was installed in the vicinities of both Ginna and NMP. T were sited approxincately the same distance inland relative to the onshore flow in onfer to maximize the comparability of sites. The Ginna station was operated by personnel from the State University o New York as Brockpon (SUCB) and the NMP site by AWS Scientific, Inc. (AWS;. Attempts were made to cohect three days of simultaneous measurements at Ginna and NMP, each d representing a different on-share flow regime. He selection of measurement days was based on forecasts provided by a forecast team headed by State University of New York at Oswego, and verified the moming of the event. He sites wem in telephone contact with each other to coordinate measurements. Weather conditions limited the measurements to two successful events. He primary measurement system was the tethersonde as described above. De proposed measurement prutocol was to obtain two vertical profiles every hour, with the tethersonde allowed to ascend at a near constant mte up to an altitude of appmximately 1000 ft, hold briefly, then descend. %is sequence was continued for up to 8 hours or as long as on-shore flow persists. Launches of radiosondes were scheduled for twice per day in order to quantify the synoptic scale conditions. De following parameters were measured with either system: dry bulb and wet bulb temperature, wind speed, wind direction, and pressure (from which altitude is detennined). 43.2.2 Subtask 2 - Detailed Lake-Induced Regime Case Studies Two tethersonde/ radiosonde monitoring locations (sites) were operated in the vicinity of Nine Mile Point to characterize the over land and vertical structure of four types of lake flow regimes: on-shore flow fumigation (3 events), lake breeze (5 events), land breeze (2 events), and the noctumal low-level 4 - 12 'M P'@ 4 S T %,$ W WF se g
f.7 F i I i jet (2 events). Table 4-1 presents a summary IOPs.uid regimes sanpled. Tethersonde Site I wa f NMP, approximately I km inland from the lake, and Tethersonde Site 2 was . located southwest o south of NMP, approximately 3.5 km irdaad from the lake. Radiosondes (Airsondes) were launched from the more inland site, Site 2. Site 1 was operated by AWS and Site 2 by SUCB. l - Exh station had the capability to launch tethersondes. The tethersonde was the primary measurement system, providing frequent, high resolution data within the toundary layer. Site 2 also had the capability to launch radiosondes which were intended to obtain vertical profiles through a deep of the atmosphere (up to 500 mb if possible) and provide information regarding synoptic scale feature influencing the area. The meteorological parameters to be measured from either system are dry and wet bulb temperature, wind speed, wind direction, and pressure fmm which the altitude can be detennined. De sanMing interval during tethersonde flights was every 13 seconds. The field progtum was designed to measure the targeted case studies in an efficient, organized manner. Intensive observation periods 00Ps), were scheduled to correspond to weather conditions favorable for the development of the desired phenomena. Each sampling period was continued as long as the desired conditions prevailed or until conditions becane relatively static. In one cas was possible to sanple more than one regime in the sane 24-hr period (e.g., Land breeze fol In the event of an a lake breeze), however, this was subject to the availability of fresh work crews. extended period of inmment weathe.r, an intensive was intermpted and a new intensive was when conditions were forecast to improve. To ensure a successful, coordinated effort throughout exh intensive the field modeling task was organiu:d as follows: The Galson task leader coordinated the overall intensive program and, through consultation with the other members of the task tean, was responsible for day-to< lay planning and communicating with the monitoring site contractors. Each site had a tean leader responsible for conducting measurement operations, supervising the site work crew, and maintaining direct communications with the task leader. A cellular telephone communication system was established between all field stations. t I 4 - 13 l 4 k
A forecast team, including members of NMP meteorological staff and the Stat University of New York at Oswego Meteorology Department, provided we guidance during the intensive measurement periods by predicting the study onset and offset, and maintaining communications with the t leader was responsible for detennining the start and stop times of the field cmw Task team meetings were held during each intensive period to discuss the forecast, review data from the previous event, and discuss problems. The measurement protocol pmposed in Phase 1 of this task was used in t di d s wem vertical pronles every hour for the dumtion of the event up to a limit of 12 hours Irnched once in the morning and again in the evening in an attempt to c 2 3 hours GMT and 1200 GMT routine sounding time at National Weather Service Office dh d of measurement, a forecast regime failed to materialize or meteorological condi i d sufficiently to make the regime unlikely, the measurement program for that e 4.3.3 Data Analysis Tethersonde data collected during the field experiment was validated, lidation by operators (AWS Scientific, Inc. and SUCB). Data from the pmfiler and RA Radian Corporation. 'Ihe 104ncter micrometeorological tower data was valid Validation of the data incl'ided inspection by a meteorologist for reasonabl Data from the conditions observed, removal of suspect data and bad data, and calibration adjust d 9MP tower was provided by the operator, Niagara Mohawk Power Corpora be already validated. 4.4 Data Summary 4.4.1 IOP Event Summaries 4.4.1.1 IOP Number 1 - May 20 to 22,1992 (On-shom Flow and Lake Breeze). 1 Temperature, dew point, wind direction and wind speed profiles for e l dix C. Following ie a brief tethersonde and airsonde flights from Sites 1 and 2 are provided in Appen 4 14 r .s i
L
- 2L a
' summary of each event measured during IOP 1. i May 20,1992. The event was performed to capture a lake breeze and associated on-shom flow conditions. A large area of high pressure was located cast of the IOP region and gmdually drifted 1 south through the day. A westerly gradient wind corr. rolled the synoptic scale setting, gradually increasing over the course of the day. Very windy conditions associated with a LLJ lirnited tethersonde operations in the moming until 0815. Measured winds were generally from the south to southwest from the surface to 1200 ft, with speeds peaking at 12 to 15 mph between 800 and 1200 ft. The onset of a lake breeze was observed at the 9MP tower between 1045 and 1100, at site I around i100, and at site 2 amund 1145, with surface winds shifting to the north and lower temperatures. De mid-day tethersonde flights showed winds at speeds of 6 to 12 mph associated with the lake hxez from the surfxe up to 900 feet, veering to east and then south between 1000 and 1500 ft. A slight temperature inversion was noted at the elevation separating the lake breeze from the synoptic s flow..De lake breeze continued to deepen to be about 1200 ft deep by cany aftemoon. The depth of the lake breeze then decreased to as low as 600 ft by 1645. The southerly retum flow persisted above the inversion level, with peak speeds rexhing 12 to 14 mph at 1400 ft during the late aftemoon. On-shore flow with a potential lake breeze component was the focus of monitoring for May 21,1992. this event. In the early moming, strong winds (> 20 mph) above a surface based radiation inversion prevented full tethersonde profiles. He winds slackened somewhat by mid-moming to allow tethersonde flights into the persistent on-shore gradient flow of northwest winds. Once the moming inversion had mixed out following sunrise, the wind remained generally 6 to 12 mph tiuoughout the day. A relatively moist layer from the surface up to about 600 to 800 ft was observed during t aftemoon. His may have been associated with a TIBL type of vertical stability shear, with cooler,- more moist marine air undercutting drier environmental air, his day is des..ving of further investigation as to the causes of differences observed between site 1 and site 2. Site 1 may have observed more radical differences due to its proximity' to the lake, and better exposure to the lake a q May 22.1992. An early moming low level jet was followed by light on-shore flow and a weak j breeze during this event. High pressure continued south and southwest of the IOP area, with a . variable gradient form west to north through the event. He early moming tethersonde launches L 4 - 15 i 'l 4 y .e y --_--_a
i showed a shallow low level jet in a strong temperatum inversion in the lowest 300 ft of the profile. A maximum wind of 17 mph fmm the south-southwest was observed in the jet, decreasing in speed an veering to west-nonhwest at 1100 ft. Solar heating created themial mixing which destroyed the inversion and allowed the jet to mix out during the moming. By late moming, the southerly land 8 beeze winds had diminished, and were replaced wi'h the northwesterly gradient wind. A lake breeze component developed thmughout the aftemoon as winds in the lowest several hundred feet be north-northwest with northwesterly wind above. Winds were relatively moist in the lowest portion of the profile, with drier air aloft. 4.4.1.2 IOP Number 2 - June 22 to 23,1992 (Land Breeze and Low Level Jet). Temperatum, dew point, wind direction and wind speed profiles for each of the IOP Numbe tethersonde and airsonde flights from Sites I and 2 are provided in Appendix C. Following is a b I summary of each event measund during IOP 2. June 22 to 23,1992. The focus of this IOP event was to capture a complete land breeze and a LL cycle duough collection of observations ovemight. These phenomena am often observed since an offshore directed land breem develops in the cooling air over the land as heat radiates to space, and the LLJ develops at the top of the radiation inversion which develops on cle calm nights. A high pressure ridge passing over the IOP sampling area during the night with c skies and light gradient winds provided an optimal setting for the development of a land breeze shallow radiation inversion had already set up by the time the first tethersonde launches took place and an extremely shallow land breeze with light south winds in the lowest 50 ft of the profile v to northwesterly gradient aloft. By midnight, the land breeze had degened to several hundred and a wind speed maximum observed at the top of the surface-based radiation inversior. The breeze maintained itself through the evening, and the LLJ reached a peak of approximately 17 m ovemight. 4.4.1.3 IOP Number 3 - August 5 to 7,1992 (Ginna Comparison, On-shore Flow and Lake Breeze) Temperature, dew point, wind direction and wind speed profiles for each of the IOP Numb tethersonde and airsonde flights from Sites 1 and 2 are provided in Appendix C. Following is summary of each event meastued during IOP 3. l 4 - 16 l
August 5.1992. Predicted on-shore winds provided an opportunity to perfonn a Ni Comparison. High pressure west of the Lake Ontario produced a moderate nonhw both the NMP and the day. Stmng onshore winds resulted in tethersonde balloon stability problems at Ginna monitoring site duuughout the event. By mid-moming, the winds had become somewh 5 h stable to allow nonnal operations at Ginna. even though the flow remained strong at 15 to 2 Ilowever, winds remained strong and actually above the 500 ft level during the entire event. inemased by mid day at the NMP site, resulting in a suspension of all monitoring follow ld tethersonde launch. It is believed that the difference in conditions betwee from a mesoscale thermal truugh embedded within in the unstable northwest flow as coo associated with the high moved across the lake. Due to the instability of the day and the limited data collected, and the apparent importance of other mesoscale features duri infonnation of value regarding comparisons of onshore flow mgimes between Ginna an expected from this event. Auguss 6,1992. High pressure passing over the southem teir of New York State, so area, offered an opportunity to measure onshore /along-shore flow near NMP. Both tedie deployed near NMP to measure this event. Mostly clear skies ovemight allowe 00, to develop with very light winds at the surface ovemight. With the first tethersonde surfxe winds were near calm to 5 mph from the south in a weak land breeze, increas mph from west-nonhwest in the gradient wind regime 400 ft above the surfre a and 200 ft at the higher base elevation of site 2. The base of the temperature inversio around 200 ft with nearly isotheanal conditions above. A weak LLJ may have been in prog around the inversion base as evidenced by the first few tethersonde flights, howev l the westerly gradient winds appears to have lessened the jet's prominence. After suiu heating of the day, the radiation inversion mixed out of the profile, and the nort mixed down to the surface at both sites. During the aftemoon, wind.s slowly backed to reflecting a backing gadient as the high moved southeast of the area. August 7,1992. High pressure over New England and a weak southerly gradient favorable for the development of a lake breeze with both tethersonde teams taking h the vicinity of NMP. " Die moming commenced with a strong surface-based inversio i { 4 - 17 l _L --n...
LLJ from the SSE. The inversion at the lower tethersonde site I was just above 400 ft, w speed maximum extending from 400 ft to 800 ft in elevation. At the higher base the temperature inversion was near 200 ft and the maximum winds extended from 20 LLJ appeared to be stronger at tethersonde site 2, where the temperature inversion surface. As the headng of the day worked to lift and weaken the inversion, the LLJ rose an weakened in response. The moming profile was replaced by a generally southerly wind and 10 mph throughout the boundary layer. During the early aftemoon, the wind dire became quite variable by the 1345 flight. At site 1, a lake breeze passed dramatica with the entire wind direction profile becoming north at very light speeds by the 1415 soun lake breeze veered into the nonheast during the aftemoon and gradually became shallow southerly g.adient winds appearing in the profile by 1600. The lake breeze never p distance between sites 1 and 2, with site 2 recording variable south winds most of th event is a dmmatic example of the localized natum of some lake breezes and the pot this regime presents to the prediction of transport and diffusion of pollutants in the sh 4.4.1.4 IOP Number 4 - August 21 to 23,1992 (On-shore Flow and Lake Breeze) Temperature, dew point, wind direction and wind speed profiles for each of the IOP i f tethersonde and airsonde flights from Sites 1 and 2 are provided in Appendix C. Fo summary of each event measured during IOP 4. A synoptic situation similar to that observed on August 5 once again afforded t August 21,1992. opponunhy to measure onshore flow regimes at both NMP and Ginna. A high pressure south of the area over central Pennsylvania, resulting in a northwesterly flow over the Lake Ontario. In the early morning, surface winds at both NMP and Ginna were relativel the surface, but considembly stronger winds were observed during the first tethersonde day just a short distr. rice above the ground. The Ginna tethersonde team was forc monitoring when the winds increased from 3 mph at the surface to nearly 25 mph at NMP tethersonde team observed more modest wind speeds generally in the 10 to 15 winds were generally westerly at both si;es, however as the day progressed winds vee more onshore northwesterly at both locations. At Ginna, the wind veered to Northerly during late moming through mid-aftemocm indicating a possible. slight lake bree 4 - 18 r I l
l 3 AT E, slightly from west-nonhwest to nonhwest in the low levels at NMP, but the effect was not as dmmatic. As with the August 5,1992 case, Ginna and NMP do not appear to compare well o specific basis due to me imponance of mesoscale feature at exh site. Weak high pressure over New York State with clear skies and a weak pressure August 22.1992. gradient provided conditions favorable for the development of a lake breeze. Mo just prior to sunrise with an airsonde launch. Initial tethersonde launches indicated radiation inversion with moderate LLJ around 200 to 300 ft above the surface. Following s radiation inversion quickly mixed out, bring nonhwesterly winds aloft down to the surface w persisted through much of the afternoon. The light winds slowly veered into the the afternoon. This veering is believed to have been a lake breeze influence, however the e quite weak and may have been a result of the proximity of the synoptic high press just west of the area by evening. Note that several parameters wem missing du pruilles due to malfunctioning equipment. ~ August 23,1992. Wann air with a high pressure area over New England and an in gradient offered the potential of a lake breeze. Monitoring began at both sites arou Pairly deep rad;ation inversion with an offshore directed LLJ of over 20 mph was o gradient winds were from the south at better than 15 mph. Following sunrise 4 ethersonde profiles throughout the layer stangth at both sites, exceeding 25 mph and mal t difficult. By 0900, the inversion was rnixing out and the LLJ gradually becoming mom Once the LLJ and inversion had mixed completely out, a south to southwest gradient-typ regime dominated, with wind speeds dropping to 5 to 10 mph. The expected la materialize during the observing period, although the light southerly winds with respect t gradient winds aloft observed by the evening airsonde, and a few brief obser i nonhwest winds at Site 1 indicated that a lake breeze was near forming. This case appe valuable fium a sense of bracketing the limits of synoptic conditions within which lake breeze develop at NMP. 4.4.1.5 IOP Number 5 - September 12 to 13 (Land Breeze, LLJ, Lake Breeze) 5 . Temperature, dew point, wind direction and wind speed profiles for each of the IOP 4 - 19 l A
tethersonde and airsonde flights from Sites 1 and 2 are provided in Appendix C. A stable synoptic pattem allowed a unique opponunity to study both a land breeze with embedded LLJ followed b lake breeze, all within the same 24 hour period. Following is a brief summary of each event measumd during IOP 5. September 12 to 13,1992 (Land bree:e/LLJ). Clear sky, cool temperatures, high pressure cente nearly directly over NMP and calm gradient indicated a potential for land breeze and LLJ conditio Monitoring at both Sites 1 and 2 was initiated shortly befom sunset. Both sites indicated a very shallow and intense surface-based radiation inversion. At Site 2, an inversion of 7 F was noted in the lowest 30 to 50 ft, and at approximately 100 ft at the lower base elevation of site 1. A low level southerly wind speed maximum was already apparent at the base of the inversion at site 1, wit breeze 400 ft deep below northerly winds aloft. 'Ihe LLJ gradually intensified to speed in excess of 20 mph just 150 ft about the surface at Site 2. Both sites observed strong winds at tree top leve the same time calm winds were observed at the surface. 'Ihe land bmeze deepened to ertvelop the entire 1000 ft profile by midnight. 'Ihe LLJ was most pronounced at Site 2, with maximum winds maching 22 mph. During the night, the inversion became less intense and deepened with the sur tempemture actually rising several degrees. Following sunrise, both sites observed a mpid of the inversion and broadening of the wind speed maximum until it had mixed out by mid-moming on die 13d1. 13,1992 (Lake Breete). The daylight hours began with the land breeze and LLJ as September discussed above. liigh pressure was located southeast of the area resulting in a weak south to southwest gradient. A general southerly wind flow of 5 to 12 mph was observed between the surfa i and 1000 ft through late moming. Winds became more light and variable after 1200 as the tetherso balloons would occasionally traverse 360 degme circles during the night. A weak, shallow lake breeze was observed to develop at Site 1 between 1310 and 1320, deepening from 100 to 900 ft by 1400. 'lhe lake breeze penetrated very slowly, reaching Site 2 around 1510, with the tethersonde showin light northeast winds between the surface and 700 ft, veering to the southwest above. Lake b velocity was between 5 and 10 mph at Site 1, but just 5 mph at site 2. The lake breeze per after 1700, when winds shifted into the southeast and a surface-based inversion began developing, indicating the offset of the lake breeze and the onset of a new land breeze. 4 - 20 t
l 5 . F, < g: m. 4.4.2 Digital Data Files i l data files. -All prufiles frum exh of the tethersonde sites for all events has b l i ted into a Over 250 profiles were collected between the two tethersonde sites. E d with a digital file and naned with the date and approximate time of the h h rsonde filenane extension. The "A" filenane extension represents a profile hile the tethersonde was was ascending, and a "D" extension indicates the data was collected w li h n ascending descending. In most instances, descending profiles are believed to f ll ing parameters: prufiles. Exh file contains a single profile; and exh profile consists o
- Data Field 1 - Year, Month, Day, Hour, Minutes, Seconds (EST)
. Data Field 2 - Height above g:ound level (m)
- Data Field 3 - Pressum (in Hg)
- Data Field 4 - Air Temperature ( C) e Data Field 5 - Dew Point Temperatum ( C) e Data Field 6 - Wet Bulb Temperature ( C) e Data Field 7 - Wind Speed (m/s) e Data Field 8 - Wind Direction (* True) lt t editing The data files are stored as ASCII text and should are readable by e software. Questions regarding the data files should be addressed to:
Galson Corpontion Modeling/ Meteorology Unit 6601 Kirkville Road East Syracuse, NY 13057 4.5 Conclusions and Recommendations l d lop a Detailed measurements of specific meteorological regimes were c detailed data base for use in the development and validation of mode Although dispersion of pollutants from power generating frilities locate l i onclusions are made: the goal of this task was mainly one of data collection, the fol ow ng c In general, good quality, high resolution data was ob favorable for exh of the four target meteorological regim i On-shore with the other special measurements taken during the Eastem 4 - 21 l l L
Flow Field Study as well as routine meteorological measurements in the area should provide researchers with a data set suitable for developing and validating conceptual and numerical models of the dispersion meteorology along the southem shore of Lake Ontario. Of the various meteorological regimes measured, the LLJ was pediaps the most dramatic and consistency observed regime. Some fonn of LLJ was observed during all IOPs, and two detailed case studies were obtained. Land breezes and LLJ were observed together. Considering the conditions which lead to the development both phenomena, it is believed that these events often occur simultaneously. Bus monitoring was successful in obtaining data during a variety of lake breeze types. Die data is expected to be useful in investigating the lake breezes of moderate strength and deep inland penetration; weak lake breezes with limited inland penetration; lake breeze enhancement of gradient wind flow; and no lake breeze under conditions when a lake breeze would typically be expected. Onshore flow offers the most subde measurements. Some moisture layering was observed along with slight temperature fluctuations. However, the subtle nature of the measurements makes comparisons between the two tethersonde sites difficult during onshore flow conditions. Difficulty in obtaining concurrent measurements at Ginna and NMP in similar weather conditions made direct comparison between the two sites impossible. Based upon the above conclusions and the experience of the project team in the perfonnance of this task, the following recommendations are made: Obtaining detailed measurements of meteorological phenomena of concem to utilities is valuable and should be conside.ed wheneu; posMble. Use of the monitoring data by researchers involved in the development and validation of models over southem Lake Ontario should be actively e60uraged. Coordination of multiple field teams is challenging due to the high variability of weather conditions over short distances. A high quality, reliable forecast and communication system should be tested and in place prior to initiating sampling such as that performed during dds task. Further investigation and monitoring in onshore flow environments should be perfomled in order to better understand the subde measurements widch occur under these flows. 4 - 22
q. -c9 4 Table 41 IOP Monitoring Data Summary N u m b e r-o f H o u r s IOP' IOP IOP' IOP' IOP' IOP 8 Task Proposed
- 1
- 2
- 3
- 4
- 5 Total Remaining
) 4.1 NMPEinna 3 Comparison 36 0 0 12 12 0 24 12 4.2 Detailed Regimes Onsbore Flow 36 12 0 12 0-12 12 36 0 Lake Breeze 60 24 36 0 12 12-24 12 60-84 0 Land Breeze 24 0 12 0 0 12 24 0 Low Level Jet 24 0 12 0 0 12 24 0-Total 144 36 24. 24 12-36' 24 144- 'O 168 l- ' LOP #1 - May 19 through May 22,1992 IOP #2 June 22 through June 23,1992 - IOP #3. August 4 through August 7,1992 l-OP #4 - August 21 through August 24,1992 IOP #5 - Sepiember 12 through September 13,1992 'Due to the lack of favorable weather conditions and tbc di;Rculty in obtaining comparable data during the first two l-attempts, a third Ginna NMP comparison was not perfonned. 4 - 23 ..t a.-_. h
Section 5.0 Evaluation of Wind and Temperature Remote Sensing Technology This section presents the results of a one year evaluation of wind and temperature ii technology installed at the Nine Mile Point Nuclear Fxility (NMP). The facility has ex st n meteorological measuring systems including a 200 ft rneteorological tower and a sodar located approximate 0.5 km west of the facility. Special remote sensing instm installed for this task near the facility for a period of one year to evaluate its perf continuous wind and temperature data aloft. A background summary of profiling eq provided in Section 6.1. Section 6.2 overviews the study objective, potentia research, and limitations of the study. A brief summary of the field monitoring inv i 6.4. - project is presented in Section 63 and the evaluation of the profiler and RASS Finally, conclusions and recommendations are provided in Section 6.5.
5.1 Background
Measurements of atmospheric parameters are most commonly obtained as dir placing the appmpriate instmment in the fluid at the location (horizontal a where the data is sought and record the appropriate values. Typically, the senso shelters, on towers, attached to balloons, or on aircraft. Data obtained in this m situ measumrnents (Schotland,1985). Instrumentation technology invotved with measurements is well established within the meteorological community. Howeve continuously make measurements of the atmospheric environment in tlure d use of in situ measurements systems, particularly in the venical dimension. Meteorological phenomena are three dimensional, and data describing this st complete understanding of phenomena in question. Examples of bounda phenomena having complex three dimensional stmcture include lake speed profiles,intemal boundary layers and terrain flows. Collection of inadequate to describe complicated venical structures. 5-1 e
l 5.1.1 Tower-based Instrumentation Where meteorological measurements are required close to the ground, the use of in situ measurement systems is simple. The necessary instmmentation can be placed in shelters or attached to towers. ~ However, when measurements are requimd at elevations above ground, these techniques limit the options available. The height of towers is limited to a maximum of approximately 1000 ft due to structural considerations, and in practice is often limited to several hundred feet due to public concems related to visual imprts and safety concems due to aviation hazards. 5.1.2 Balloon-borne Instmmentation in the past, " temporary" systems have been employed to gather needed measurements of meteorological parameters above the height typically covered by tower-based instrumentation. "Ihese temporary measurement systems have most commonly taken the form ofinstmmented free flying balloons called radiosondes (or airsondes). 'lhe instrument pxkage of a typical radiosonde is capable of measuring air temperature, wet bulb temperatum, and pressum. The height obtained by the instrument is detennined from the pressum and temperature relationships. Wind speed and direction is determined by either manually tmcking the balloon using an optical theodolite system, tracking the balloon with radar, or using a Loran navigat onal tracking system in the instmment package. i While radiosonde systems are capable of providing atmospheric data between the surfre and tens of kilometers in elevation, they are limited in that they provide only single point data in spre and time as the instmment passes tiuough any given elevation. Thus, radiosondes do not allow continuous observations at a specific elevation. In addition, the instrument package may only be used once since it is impractical to retrieve the systems following use. Thus radiosondes are relatively labor intensive - and expensive for use in obtaining continuous measurements of meteorological parameters in the vertical dimension. An altemative to the " disposable" radiosonde is the tethersonde. Like the radiosonde, the tethersonde system consists of an instmmented package attached to a balloon. However, in this instance, the balloon is tethered to the ground and may be raised, lowered, or temain at a given elevation using a power winch system. The insuument package contains a radio tmnsmitter which telemeters data to a 5-2
y ry ground receiver where the information is logged on a computer. The tethersonde offers more control than the radiosonde over the elevation and duration of measurements taken in the boundary layer. Most tethersonde systems are limited to use below 1000 meters, are unstable and unreliabic in suung winds (>10 m/s), must be brought to the ground frequendy in onfer to replenish batteries, and are labor intensive. In addition, only one elevation can be sampled at any given time. Recently though, several manufacturers have developed tethersondes capable of handling sevemi instrument pxkages along the tetherline at varying elevations. 5.1.3 Atmospheric Remote Sensing Instnimentation Recent technological advances have led to the development of remote sensing atmospheric profiling systems which are capable of condnuously measuring atmospheric parameters above the ground. This technology offers many advantages over the older techniques described above; namely, the continuous, unattended observation of meteorological pammeters at a number of venica! elevations simultaneously without having to rely on in situ instrumentation. l 5.1.3.1 Acoustic Sounders and Sodar l Acoustic remote sensing equipment is based upon the principle that a volume of air scatters acoustic energy incident upon it. Scattering is due to wind speed and tempemture discontinuities in die { sampled volume of air. Most of the scattering occurs in the direction of propagation, but a small percentage of the energy is scattered bxk to the source. An xoustic sounder transmits a strong roustic pulse (typically around 100 watts) venically into the atmosphere and listens for that portion 1 of the transmitted pulse that is scattered bxk to the transmitter. De monostatic sounder uses the ) same roustic driver to both tmnsmit and receive the signal with a single antenna pointed venically. Theory relates the amount of return signal to velocity and thermal stmeture functions of the atmosphere (C, and C,). He structure functions can be interpreted as expressing the degree of I instantaneous velocity or tempemture difference between points a unit distance apan. The existence of a temperature gradient and small-scale turbulence create local instantaneous temperature differences greater than the mean venical temperatum gradient. A strong retum signal can be produced either by l an unstable temperature gradient and little wind shear (as is found in the convective boundary layer) 5-3 } j
d in the stable boundary or with a stable potential temperatum gradient and large wind shear (as is foun i layer). As a result, qualitative atmospheric stability and temperature One strength of sounders is the ability to detect fmquency shifts betwee backscattered acoustic pulse. Frequency shifts are caused by the dop itter. In proportional to the speed of sound of an air parcel moving toward or a i d t various elevations this way, the speed of the air along the axis of tmnsmission can be detenn ne a hd between the surface and roughly 1000 meters aloft. This range is high i d high ambient conditions and can be limited by such as things as high wind speeds, pmcipitat i tic sounders noise levels. In addition, environmental factors must be considered in locat ng a di d tees, which giving adequate consideration to stationary sounes of backscatter such could lead to erroneous data. fh d rin The doppler sodar uses the acoustic backscatter and frequency shif h d achieves such a thme axis system capable of measuring the three dimensional wind profile. ld measurements using a combination of three antennae, one venically poin h th r With this obliquely to the venical (approximately 18 ) and horizontally oriented 90 t i l trigonometry configuration, and calculation of velocity of the air along each axis of the h d The two tilted allows the calculation of the three dimensional wind profile at heights above t h i l antenna is used to antenna are used to calculate the horizontal wind speed and direction, and t e d for the calculate the venical wind speed as well as correct the calculation from the h done away with the tlute antenna venical component of wind. Recently, advances in sodar technology ave di 'lhe acoustic concept, replacing it with a single array of vertically-pointing small acoustic h driver array is then sequenced to operate in a way such that the bea hi t l wind. backscatter data from the direction oblique to the venical allowing ca cul ff f the same This type of antenna system is referred to as a phased-array soda height and operational limitations as the acoustic sounder, 5.13.2 Radar Wind Profiler i Microwave atmospheric pmfilers are similar to sodars in that they technology improves upon some i l energy to measure the tluce dimensional wind component. This relat ve y b of the range and environmental limitations of acoustically-based systems y o 5-4 ,..m
L much higher wavelength range. Like the sodar, the pmfiler obtains measurements of the vertical and horizontal wind pmfile by directing the signal. Three antennae are oriented in a similar manner similar to the sodar, or, more recently, by electrically steering the microwave beam direction in a way similar to the phased-array sodar system described above. A number of different profiling systems are under development in the United States and sevemi radar profiler systems have recendy been commercialized (eg. the NOAA 50Milz deep tropospheric profiler, the UNISYS 4M Mllz Radar Profiler, and the Radian /STI LAP-3000 915 MHz lower atmospheric profiler). De 50 Mllz system is a research grade profiler capable of sensing winds from 1 or 2 km to over 10 km. De 4M Mllz profiler is tenned a " middle tmpospheric" profiler and is capable of retuming reliable data between about 500 m and 7 or 8 km above the surface. The National Weather Service is currently installing a demonstration network of 404 MIIz profilers in the U.S. great plains region. Finally, the 915 Mllz profiler has recently been commercialized under an agreement between Radian, STI and NOAA for use as a lower tmpospheric profiler, and is believed capable of retuming reliable data between 100 m and 5 km. As in the case of sodars, care must be taken in siting Radar wind profilers to avoid exposing the microwave beam to objects which pose a tfucat of backscatter and resulting " ground clutter". Ground clutter objects such as trees, power lines, etc., sway with the wind and energy reflected from the swaying objects may be interpreted by the profiler as good data. 5.1.3.3 Radio Acoustic Sounding System De Radio Acoustic Sounding System (RASS) is another emerging technology for measuring the atmospheric boundary layer. RASS makes use of both sodar and mdar profiling technologies. By combirung the two techniques, and providing for additional signal processing capability, the vertical profile of virtual temperature' (T,) can be determined by making use of the relationship between the I ~ ' Virtual temperature is the temperature of dry air tuving the same density md pressure of moist air. The virtual temperature is atways greater than the actual temperature md is approximated by l T,-(1461g)T where T is the temperature md q is the speciGc bumidity (Huschke,1959). 5-5 I
t s 2 and tempenture. In the RASS configuration, only the vertically pointing antenna of the Sodar and Profiler are ~ Sodar produces an acoustic didurbance which is tracked by the radar profiler as it trav away from the antenna.- Radar is capable of detennining the speed of the acoust travels vertically, which in _tum is used to calculate T, at each of a series of user specified ran RASS suffers fmm some limitations in range due to atmospheric dissipation of the aco also transport of the pulse out of the radar's field of view by horizontal winds. In ge - perfonn best in a strongly stratified atmosphere with light winds. 5.L4 ' Applications to Nuclear Facilities Understanding meteorological influences on the transport and diffusion of air pollutant power genemting facilities is greatly enhanced with knowledge of meteorological par various elevations above the ground. Current pollutant dispersion and transport models m L reladvely simple assumptions regarding the atmospheric parameters influencing any may be released by a source. Some of the more significant assumptions with respect to . meteorological inputs are: LWind speed and direction is assumed to be unifonn throughout the h' rimnta o e L of the model, Only one stability class is generall) accepted :r ducribe both horizontal an
- diffusion of the plume (although some models are capable of accepting different a-
-I horizontal and vertical stabilities),
- I Stability, wind speed, and wind direction are assumed to be mnstant in time up t about one hour, and Vertical variations in the stability class are not allowed below the mixing height.
o' t l. 4 4 } b The speed < f m3und is related to teroperature by the expressim '2 c=[iR h ific where R is the gas mostant T is the teenperamre; Y is the istio of specific beat of air at omstant pre , heat of air at onostant volume (c,) (Huschke,1959).- .5 6 p_ t ( h
a ~y Such assumptions can be restrictive when trying to predict tanspon and diffusion in areas where meteorological parameters such as wind speed, wind dimetion and stability change spatially and over short time periods. Such situations are frequendy observed in coastal mgions which are influenced by land and lake breezes, vertically varying stability conditions (particularly during on-shore flow), and locally induced wind speed and direction changes caused by changes in surface ruughness between land and water ares. In such cases, high resolution observations of the spatially (horizontal and venical) varying *vind field can be important in describing the transpon and diffusion conditions at any given moment. Tall towers are capable of measuring some conditions, however due to the limitations on tower measurements discussed above, remote sensing technology offers the opponunity of collecting data at elevations which may be more closely related to the wind and stability conditions that pollutant plumes fmm an elevated source undergo. For instance,in the case of lake bmeze, near the surface the flow is genemlly on-shore (air flowing from the water body towant the land), while aloft, the flow is usually oppasing this circulation (from the land toward the water). In this instance, prediction of the tmnspon of a plume which is elevated to the height of the opposing circulation may be improperly handled if wind data fmm a meteorological tower with limited vertical extent indicates that on-shore flow is occurring. Themfore, monitoring of meteorological parameters at elevations well above 60m provides valuable data for operations involving the calculation of transpon and diffusion in mgions of complex meteorological flows. 5.2 Study Objective The objective of this task was to install and operate a 915 MHz mdar profiler and RASS for a period of one-year in the vicinity of NMP for the purpose of evaluating the performance of the two systems and assessing their potential as emplacements for tall, tower-based monitoring instmments. 5.2.1 Study Goal l The goal of this task is to successfully operate the radar profiler and RASS for a period of one year I 5-7
and evaluate the system perfcancnce on the following criteria: Quantity of data (ie. Annual data recovery rate greater than 907c), Quality of data (based on comparison with independently collected data sets), Level of effon required for routine servicing. Frequency and severity of system failures, and Estimate of the level of performance that can be expected if the systems were permanently deployed. Following the evaluation, recommendations will be made regarding the ability of the radar profiler and RASS to serve as a replacement for tall meteorological towers and monitoring the lower troposphere in enough detail to define the complex meteorological conditions often encountered in the coastal zone. 5.2.2 Potential Applications As indicated in the task objectives, the evaluation of the radar profi!er and RASS will serve as a basis for detennining the ability of these systems to serve as reliable lower atmospheric monitoring systems for the purpose of observing meteorological pammeters imponant to the transpon and diffusion of pollutants in regions experiencing complex ' meteorological flows. The evaluation addresses the ability of the prufiler and RASS to serve as a poternial replacement for tall tower-based monitoring systems by evaluating the comparability of the measurements to xcepted standards, data recovery rates expected from meteorological systems at nuclear fxilities, and operation and maintenance requirements. Tif.; research provides infonnation of interest to utilities wishing to investi; ate the potential of radar wind profilers and RASS to provide additional in ormation related to the followilig concems: r
- Localized atmospheric flow regimes, e Regional pollutant tmnspon, a Mixing height, and
. Venical wind profile variations. 5.2.3 Limitations of Study l l Every effon was made to minimize the limitations of this study. However, inevitable limits to the operation and evaluation of the equipment exist that are beyond the contrul of the investigators. First, 5-8 l I e
g ? during this field study, the LAP-3000 profiler underwent a generational change in sensing technology. Due to the time-table required by this particular study, the first generation technology was employed. De second generation system employs a phased, sing 1c-antenna system and new pulse coding, both of which maximize the data recovery rate. I Secondly, siting factors can improve or decrease prufiler perfomiance. Among these factors include instrument configuration, presence of clutter sources, sources of radio interference, and atmospheric conditions. As will be discussed, this panicular study suffered from ground clutter problems which limited data recovery. He evaluation study looks closely at the effect of atmospheric conditions on profiler perfonnance. Finally, the evaluation of the pmfiler perfonnance and comparability to other measuring systems is limited. These limitations stem from the difficulty of matching the profiler and comparison instrument measurements in space and time. Also, errors involved in the use of comparable instruments can, themselves, limit the analysis. 5.3 Field Monitoring Summary For this task, Galson Corporation provided overall task management, site operation, and final report oversight. A LAP-3000 915 MHz Radar Profiler and RASS was leased from Radian Corporation for a period of thineen months. Radian also provided data validation and reporting. The evaluation of the mdar profiler and RASS was perfonned and reported by Sonoma Technology, Inc. (STI) under a subcontact with Radian. Both Radian and STI are jointly licensed under the terms of a Cooperative Research and Development Agreement (CRDA) with the National Oceanic and Atmospheric Administration (NOAA) to provide the LAP-3000 and RASS technology to non-govemment users. During the pmject kickoff meeting in July,1992, the project tean discussed, among other topics, the siting and operating parameters of the Radar Psofiler and RASS for the one-year field monitoring effort that would best address the task objectives. Upon selecting a number of candidate sites, representatives of Galson and Radian su veyed the locations, taking photographs in all directions and identifying visible sources of potential interference. 'Ihe final site selected (PRF) was located near the micrometeorological tower installed for the evaluation of stability classification schemes, 5-9
l l l b l approximately 0.75 km from the lake shore (See Figure 1-1). 1 Galson Corporation prepared the PRF site for the instrumentation including supplying power and telephone and prepping the shelter for the profiler and RASS computer equipment. Radian engineers along with Galson technicians installed a LAP-3000 Radar Profiler and RASS on October 31,1991. Galson Corporation then operated this profiler continuously until November 1,1992. On a routine basis, the Galson site operator would perform data backup procedures on the control computers and perfonn other routine tasks. In the event of problems, the site opemfor would make emergency visits to the site. Both Galson and Radian mutinely contxted the profiler and RASS control computers duough telephone telemetry and downloaded data and determined operational status. Galson and STI, tluuugh a separate contract with NMPC, developed software to allow near real-time rcess to the data once per hour. The downloaded data formed the raw data set used in the data validation and reponing. Data reports were developed monthly, and provided to ESEERCO through monthly progress reports. Shortly after installation, it became apparent that mdar profiler performance was degmded by. reflection of the signal off trees and power lines in the vicinity of the profiler. This effect is referred to as ground clutter. The ground clutter problem was first noted in the November 1991 Data Summary Report (Galson,1992). While care was exercised in selecting the k) cation for the profiler and the kication met the siting criteria as originally outlined by Radian, several clutter sourecs out of view frum the site became important reflectors of the microwave energy emitted by the profiler. The most notable ground clutter source appears to have been the main power transmission lines extending south from NMP approximately 0.5 km east of the profiler. The ground clutter effects appeared to be greatest widun the lowest range gates measured by the radar, and rarely extended above 1500 m (approximately equivalent to the distance between tne radar and the ground clutter objects). Once the ground clutter problem was noted, a series of actions were initiated in an attempt to alleviate or at least reduce the problem. First, the antennae were re oriented, attempting to move the ground clutter targets out of the microwave signal beam. While it was possible to get the ground clutter out of the main beam of the prufiler antennae by repositioning, the objects presented such a large reflection target that the side lobe transmission caused reflections which continued to dominate the 5 - 10 l
e signal. Next, Radian Corporation attempted to modify some of the operating pammeters such as signal pulse length, range gate height and other, critical opemting parameters. These modifications appeared to have minimal effect on the profiler perfonnance. Subsequently, Radian, STI and NOAA personnel reviewed the ground clutter suppression algorithm employed in the profiler software, attempting to determine ifimprovements could be made. A revised program was implemented and tested during June,1992, with only modest improvement. Finally, it was discussed whether moving the profiler to an altemative site would be possible within the project budget. During a toutine maintenance visit, the Radian engineer identified a potential site west of NMP which appeared to present fewer ground clutter targets. However, after discussion among the project team, including the ESEERCO project manager, it was detennined that relocation was not practical within the current project scope. First, the selocation would have represented a major additional cost in piepping the altemate site and relocating the equipment. Second, at the time the relocation was discussed, nearly six months of data collection had been completed covering mainly the cold weather months. Since one of the task objectives was to evaluate operation during different weather conditions, it was felt that selocation would make a comparison between winter and summer performance at the same site impossible. Finally, there was significant concem over the potential for offsite noise impacts from the RASS roustic signal genemtors. A privately owned summer camp is located just west of the NMP property line near where a better profiler operating location had been identified. He project team concluded that the 10-minute xoustic emission from the RASS each hour would have been audible at offsite receptors, and presented a potential noise nuisance to anyone located at the camp. As a compromise solution to relocated the profiler mid-way through the project, a short-test of the profiler at an altemative site was organized to take place at the end of the monitoring program, ne project team arranged to operate the latest production version of the profiler for approximately 4 days. It was hoped that a variety of weather conditions would be available in which to test the performance l of the system and provide at least a qualitative estimate of profiler performance in the absence of significant ground clutter sources. l it should be noted that the ground clutter problem appears to have been confined to the Radar Profiler and should not have influenced the RASS. Since the RASS uses only the vertical antenna, it is i 5 - 11 1
p... believed that the side lobe reflections were less imponant. Another problem observed with the site was transpon of the cooling tower plume directly over the profiler. 'Ihe cooling tower plume presented such a significant target that it dominated the signal from both the profiler and RASS to such an extent that data collection above the plume could not be j performed. Litue can be done to prevent this problem, other than relocating the profiler to a location fanher away fmm the facility and in a directior where the frequency of winds is such that cooling tower plume overflight is minimized. Details on the data collected and a summary of this activity are provided in the Monthly Progress repons submitted to ESEERCO at regular intervals throughout the field operations of this project. 5.4 Summary of Radar Profiler and RASS Evaluation Following the close of monitoring, all system data and relevant operational inforraatbn was provided by Radian and Galson to STI for use in the evaluation repon. In addidon, other data from the pmject was made available to STI including 9MP tower and sodar data, micrometeorological tower data (MMT), and tethersonde and airsonde profiles from TS1 and TS2. During the development of the evaluation, a number of problems were noted with the compamtive data. First, significant reformatting was required before the various data bases could be compared. Secondly, calibration ermrs were noted in the tethersonde temperature soundings which were used to evaluate the performance of the RASS. Finally, an error was discovered in the manner in which the tethersonde l and airsonde wind direction had been calculated. Data errors were corrected prior to analysis. 'The complete evaluation report, " Evaluation of the Performance of a 915 MHz Radar Pmfiler and RASS during the Eastem Lake Ontario On-shore Flow Field Study," submitted to Galson by STI is provided in Appendix D-1. The evaluation repon provides extensive information on the following topics: j
- specific objectives of this task
- detailed radar pmfiler and RASS system descriptions l
- data sources available for determining the profiler and RASS performance,
- service and maintenance requirements of the system e data recovery performance as a function of site fxtors and atmospheric conditions 5 - 12
e intemomparison of the system with other data collection platforms e conclusions and recommendations for pmfiler and RASS performance The mader is referred to Appendix D-1 for the detailed evaluation conclusions and recommendations. j llowever, in the interest of brevity, we have attempted to summarize the conclusions of the evaluation repon below: l !) System availability was excellent. Total downtime amounted to just 3.7% of the year. 2) Data communications systems operated nearly flawlessly throughout the experiment. 3) Reliability with respect to data recovery was not demonstrated for this installation. His is almost exclusively due to interference with ground clutter. 4) Data recovery for wind data was best during the following conditions: - Summer daytime - Low atmospheric pressure at altitudes above 1500m - liigh atmospheric pressure at altitude below 1500m - Wind blowing from the nonh, east, and southeast l - Precipitation i 5) Data recovery rates for temperature were much lower than expected. De causes are not clear. I 6) Data recovery for temperature data was best during the following conditions: I - Summer and winter daytime - Cold and dry conditions ,1 - Wind blowing from the northwest tiuough east 7) Comparative performance of the profiler and RASS against the tethersonde and airsonde i systems was very good and comparable to results obtained in previous investigations. Average bias for wind speed was -0.15 to -0.5 m/s and -4.2* to -6.7* for wind dimetion. The Root Mean Square (RMS) difference for wind speed was 2.0 m/s and was 37 for wind direction. Average differences for vinual tempemture measurement were -0.17 C, with an RMS difference of 0.63 C and a correlation 0.98. 8) With the exception of the need to remove snow and ice buildup in the antennae, maintenance and service requirements for the system were minimal. He STI evaluation repon states "...that these remote sensing instmments can be an excellent source of data.o meet meteorological monitoring requirements for air pollution and emergency response applications in the shoreline environment of Lake Ontario." However, Galson concludes that the l evidence is clear that the systems can not replace tall tower measurements but rather serve as enhancements. De lowest achievable range gate for the current radar profiler and RASS system, is around 100 m. His is still too high to resolve boundary layer structure near the ground where most { of the thennal and mechanical fluxes occur. In addition, limitations on data recovery rates presents a l f problem, panicularly for regulatory applications. While the evaluation report shows that data recovery ( mies over 90% are achievable in the lower range gates, the dependance of this perfonnance on siting 9 5 - 13 q i d
and atmospheric conditions is worrisome. De STI evaluation report concedes our above conclusion by stating: "In conjunction with tower observations to fill the data gap between the profilert lowest range gate, the profiler and RASS can provide aloft data suitable for use in regulatory and or research transport diffusion models." Re results of the profiler resiting tests are presented in a report fmm STI to Galson entided "Results of the Re-siting of the 915 MHz wind profiler at the Nine Mile Point Nuclear Generating Facility" and is provided in Appendix D-2. In reviewing the profiler re-siting report,it should be emphasized that the profiler was not an exact clone of the system used during the one-year monitodng pmgram, but rather the latest production version of a phased-array system. He phased-array profiler represent the latest in technology and are an improvement of the older three-axis system. Never-the-less, the following results were obtained imm the re-siting study: Ground clutter at the new site was significandy less than the previous site. The ovemll quality of the wind data collected at the shoreline site appeared better dian that collected at the previous site. This is likely due to the use of the phased-array system and the reduction in ground clutter. 5.5 Conclusions and Recommendations A 915Milz Radar Pmfiler and RASS were operatert for a perhv1 cf one year in the vicinity of NMP. The purpose of the monitoring was to evaluate the perfonnance of these new monitoring systerns as possWie replacements for exisiting tall meteorological towers and provide enhanced data at levels we above that typically observed by the tall towers. Based upon the performance and operational evaluation of the systems, the project team presents die following conclusions and recommendations based upon our analysis of the data and evaluation report: Radar profilers and RASS are not a replrement for tall towers. They are, however, capable of supplementing the tower-based measurements with detailed observations l between the boundary layer and the middle troposphere. 5 - 14 l
E i s i ff. l .a
- y Combined with the existing NMP 200 ft meteorological tower and sodar for profiling 1
n the lowest portion of the boundary layer, the profiler and RASS can provide valuable infonnation on plume level wind and temperature stmeture, particularly in lake breeze retum flow, and onshore flow conditions. The profiler and RASS provide aloft data with considerably better time and vertical resolution than that available from traditional balloon-bome profiling systems, ) providing data of sufficient detail and accuracy for regional scale numerical modeling and initialization of site-specific numerical models. { Operational reliability is high, even considering that tle profiler system operated is still developmental and not the current commercial version available. Data recovery is dependent on operational status, weather and siting conditions. Resolution is good, but is still too coarse at low elevations for observing some very localized features such as a TIBL structure. Great care must be taken in siting the eq'dpment to avoid sources of ground clutter. A thorough siting study which includes testing the profiler at candidate locations prior to pennanent installation at the selecti j site is highly recommended. Future use should be limited to the latest produedon version of the equipment. I Prior to installation, it should be verified that the approach for dealing with snow and ice buildup is appropriate for the site. Maintenance visits occurring regularly every 1 to 2 weeks should be sufficient for most operations. A shorter pulse length (60 m instead of 100 m) should be employed for the RASS if the application is to better resolve boundary layer temperature structure. 'Ihe shorter pulse length allows use of smaller renge gates, thus increasing the number of available data points in the vertical. Care should be take to assure that data recovery is not effected by use of a shorter pulse length. A detailed Quality Control and Quality Assurance plan should be developed for a pennanent installation which includes routinely comparing the profiler and RASS data with an independent observation set is recommended, i 1 'i 5 - 15 i L________ ____.a
~5.6' Preferences Hunske, Ralph E., ed.1959. Glossary of Meteorology. Boston: Ainetican Meteorological Society. ' Schotland, Richard M.1985. Remote Ground-Based Observing Systems. In David E.' Houghton, ed., ' Hondbook of Applied Meteorology. New York: Wiley, pp. 361-379, i a t l f 9 5 - 16 _ _ __ _}}