ML19329E355

Relationships Between Climate & Regional Variations in Snow Cover Density in North America.

ML19329E355
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Issue date:	12/31/1969
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RR 267 Research Report 267 RELATIONSHIPS BETWEEN CLIMATE AND REGIONAL VARIATIONS IN SNOW-COVER DENSITY IN NORTH AMERICA ,

Michool A. Bilello  :

i D ece m b e r 1969 1

CORPS OF ENGINEERS. U.S. ARMY COLD REGONS RESEARCH AND ENGNEERING LABORATORY HANOVER. NEW HAMPSHIRE ANO A L.E S DIS R TON IS UNI.1M T D.

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. RELATIONSHIPS BETWEEN CLIMATE AND REGION AL VARIATIONS IN SNOW-COVER DENSITY IN NORTH AMERICA Michael A. Bilello

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PREFACE This report was prepared by Michael A. Bilello, Research Meteorologist, of the Research Division. U. S. Army Cold Regions Research and Engineering i2ha=tary. It is published under DA Task 1T061102B52A02, Research in Military Aspects of Terrestrial Sciences - Military Aspects of Cold Regions Research.

The data used in this report were made available through the coobined efforts of personnel associated with the Air Weather Service, U.S. Air Force; the Weather Bureau, U.S. Department of Commerce; and the Meteorological Branch, Canadian Department of Transport. The author wishes to thank Dr.

Robert Gerdel, formerly of USA CRREL, now retired, and Mr. Frederick Sanger, USA CRREL, for their technical review of the paper. Mr. Roy Bates, USA CRREL, assisted with the computation and tabulation of the data.

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CONTENTS Page i In tr oductio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 N na # variations in density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Monthly increase in dennity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Nomograph to estimate average snow-cover density . . . . . . . . . . . . . . . . . . . . . 5 Test and application of the nomograph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Di sc us sio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

- Literature cite d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Appendix A: Observed, weighted snow-cover densities for stations in Tr.ble I 13 l ILLUSTRATIONS Figure

1. Locations of stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 i

2. Frequency curves for density Categories 1-4 . . . . . . . . . . . . . . . . . . . . . 4

3. Increase in density from November through Maren for Categories 1-4 5

4. Nomograph for estimating average seasonal snow-cover density..... 7

5. Estimated versus observed densities for ten test stations.......... 8

6. Average seasonal snow-cover densities . . . . . . . . . . . . . . . . . . . . . . . . . 8 P

TABLES Table

. I, %= mary of snow. cover densities and ' climate for 27 stations in North America and Greenland (1952-63) . . . . . . . . . . . . . . . . . . . . . . . 3 .

II. Observed average snow density, seasonal air temperature and wind speed for stations in Cold and Williams's (1957) report used ,

to te st nomograp h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 III. Stations for which average snow-cover densities were estimated from

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RELATIONSHIPS BETWEEN CLIMATE AND REGIONAL VARIATIONS IN SNOW-COVER DENSITY IN NORTH AMERICA by Michael A. Bilello INTRODUCTION Knowledge of the regional distribution of snow-cover density would help solve numerous winter problems. For example, the density-dependent thermal conductivity of the snow cover greatly influences the rate of penetration of ground frost and the growth of ice on lakes and rivers. Trafficability of men and vehicles depends strongly upon the density of the snow cove r.

Dense snow may support a wheeled vehicle. Sinkage in snow of low density seriously impedes or prevents movement. Studies in hydrology and in snow removal also require knowledge of the density of the snowpack during the winter.

Vlis study investigates the regional variations of snow-cover density in the North American Arctic, Subarctic and Temperate Zones for the nonmelting period only. This permits

direct association of regional variations in density with air temperatures and wind speeds, and the development of a method by which average snow-cover densities can be estimated where the influence of melting on density may be disregarded. The purpose of this correlation is to make use of climatological data to determine snow density in areas where such measurements a

bave not been made.

An investigation of this type requires concurrent measurements of snow-cover density and the meteorological elements. To obtain such measurements, a systematic snow observation procam began during the winter season of 1952-53 at various locations in Canada. Green 10ad and tne United States including Alaska. The observations were made at weather stations supported by the United States Air Fo'rce, United States Weather Bureau and the Meteorological Branch of the Canadian Department of Transport.

Two to eleven years of snow-cover data have been coropiled for nine locations in Canada, ten in Alaska, seven on the United States mainland and one in Creenland. The Creenland station, Sondrestrom, although not on the North American continent, was included because of its proximity to the network.

The snow observations, made weekly and sometimes biweekly in accordance with standard procedures described in USA CRREL Instruction Manual No.1 (USA SIPRE,1954),

provide density, temperature, and hardness data on the layers of snow in vertical profile. The different layers of snow are delineated by structural or textural variations identifying periods of major snow accumulation or metamorphism.

Previous studies (Wengler.1914; Rikhter,1945: Formozov,1946: a

• Klein,1950) show that there are important regional differences in the density of the snow cover thaighout the Northern Hemisphere. In an earlier study (Bilello,1957), it was found that the snow over during the winter months is denser in the Canadian Archipelago than in the interior of . 'aska.

Additional data have since become available which permit extension of the analysis to ot ar parts of North America.

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2 CLIMATE AND SNOW-COVER DENSITY IN NORTH AMERICA REGIONAL VARIATIONS IN DENSITY In the analysis of the new data a weighted mean of snow-cover density for each observation was used (as was done in the earlier study), thus:

Thickness Te ot Observed Weighted of each total snow sacaw 1 layer depth density density (ca) (g/cm') Wcm')

Layer 1(bottom) 6 20 0.205 0.041 4 Layer 2 15 50 0.290 0.145 Layer 3 (top) 9 30 0.230 0.069 Total 30 100 0.255 This method of computation was used to allow for the variations in thickness and density of the i different layers of snow.

The average seasonal (November - March) snow-cover density for each station (Table 1) is the arithmetic mean of all the weekly mean weighted values based on a total of over 2500 obser-vations. The number of years of record for each station is also shown. (Data are presented in Appendix A.) For some low latitude stations November and/or March was excluded because the observed average monthly air temperatures were above freezing and some melting may have occurred. Periods of above-freezing temperatures that may have occurred during the other winter a months were assumed to be brief, and effective only in raising the temperature of the snow with-out causing melt; they were therefore disregarded. The effect of one day of freezing rain or thaw during midwinter would have little influence on the snow cover and would not be reflected in the monthly average density.

The concurrent average seasonal air temperature and wind speed.for each station are also given in Table 1.

Analysis indicated that the stations could be put in four categories based upon the observed

' densities, climatic factors and to some extent on geographical location (CRREL network. Fig.1).

These categories were grouped so as to emphasize regional, rather than point, variations in snow-4 cover density. Category l included the four stations with lowest observed densities (between O.199 and 0.233 g/cm'). These stations are located in the interior of Alaska and western United States and have,in general, light winds. The second group comprises nine stations with average densities between 0.241 and 0.268 g/cm', most of which are near the coast. The seven stations in Category 3 have densities between 0.279 and 0.297 g/cm'. This group does not have a geographic entity; the stations are located both inland and near coasts. Category 4 consists of seven Arctic stations where the highest densities (between 0.320 and 0.363 g/cm') and the lowest seasonal temperatures were observed. The frequency curvesin Figure 2 showtheincreasing densities of the four categories. Naturally, theloca1 topography and vegetation create differencesinthe density from pointio point within a categorically defined region. Deviations fromthe ayerage value for each.

region can also be expected from month to month and yearto year. The standardideviations fromthe ,

average values (Table 1) show the extent of these monthly and yearly variations. l Skewness (departure from symmetry) coefficients, based on the quartile method (Mode,1948),

were computed for each station and are shown in Table 1. The quartile values were obtained by plotting the observed snow densities proportionally between 0 and 1007. frequency distribution and precisely interpolating between the densities for the 25, 50 and 757. locations. All but two stations i .

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CLIMATE AND SNOW. COVER DENSITY IN NORTH AMERICA 3 in Categories 1 and 2 show posit.'ve skewness, i.e., the peak of the frequency curve is toward lower densities, and all but three of the stations in Categories 3 and 4 show negative skewness, i.e., the peak of the frequency curve is tcward higher densities. This difference supports the reparation of Category 2 from 3, but since the significance of the computed values has not been determined the'results are used only as an indicator.

Table !. Summary of snow-cover densities and climate for 27 stations in North America and Greenland (1952 63).

Average .tverage Years seasonst Aversgo seasonst of snow Std Skew. seasonst wind Station record der ness temp 1 speed t l density (s/cm ) (*C) (m/sec) l Category 1 Elelson AFB (Fairbanks). 6 0.199 0.053 +.178 -20.3 1.3 Alaska i Tatalina. Alaska 9 0.313 0.047 +.010 -15.5 2.1 l Hill (Ogden). Utah 8 0.2 19 0.083 +.282 - 1.7 3.6 Calena. Alaska 10 0.233 0.060 .088 -20.7 2.2 l

Category 2 Utopia Creek. Alaska 9 0.241 0.069 +.154 - 19. 1 2.8 Naknek. Alaska 2 0.244 0.035 +.361 - 9.2 4.3 l Saglek. Labrador 6 0.2 W 0.091 +.588 - 10.6 3.8 Criffiss (Rome). N.Y. 9 1.252 0.052 + 121 - 4.3 3.1 Malmstrom (Crest Falls), 8 0.252 0.046 +.178 - 2.2 5. 4 Montana Elmendorf ( Anchorage). 7 0.253 0.081 +.035 - 8.6 2.5 Alaska Emeet Harmon 9 0.255 0.10 2 +.100 - 4.9 5.1 (Stephenyttle).Newf.

Sondrestrom. Greenland 5 0.26 2 0.032 +.522 -17.6 3.1 Coose Bay. Labrador 2 0.268 0.068 .451 - 10.9 4.1 Category 3 Sparrevohn. Alaska 9 0.279 0.045 .047 -11.5 2.7 Sault Ste Marie. Mich.' 10 0.290 0.057 +.101 - 8.4 4.4 Frobisher. NWT 4 0.29 2 0.066 .555 -22.8 4.8 Fargo. North Dakota

• 2 0.29 4 0.0 50 +.204 - 9.4 6.6 Loring(Caribou) Me. 11 0.294 0.080 .005 - 9.2 5.3 Northeast Cape. Alaski 2 0.296 0.033 .237 , - 10.2 5.9 8 0.297 0.073 .0 18 - 5.1 4.5 Wurtsmith (Oscoda).

Michigan Category 4 Cape Lisbume. Alaska 2 0.320 0.05 a +.141 -16.2 5.5 Barter Island. Alaska 3 0.325 0.0 59 .654 -25.3 5.9 11 0.326 0.05fs .325 -35.3 2.6 Eureka. NWT

• 10 0.342 0.044 .0 16 -30.2 5.4 Resolute. NWT

• 10 0.345 0.06t .044 -30.5 2.7 Alert. NWT

• Mould Bay. NWT

• 7 0.354 0.0 50 .038 -32.2 4. 3 11 0.36 3 0.051 .054 -33.2 4. 4 Isachsen. NWT *

• U.S. Weather Bureau and Canadian Deparuneat of Transport stauons. All others are U.S. Air Force.

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1. t t t I t 0 ato a2O 0.30 0.40 a50 0EN$17 Y. g/cm 3 Figure 2. Frequency curves for density Categories 14.

Curves comprise line segments connecting miit-points of class intervals 0.10- 0.15 g/cm', 0.15 - 0.20 g/cm*, etc.

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l 5 j CLIMATE ANL R COVER DENSITY IN NORTH AMERICA MONTHLY INCREASE IN DENSrl'Y The metamorphic processes which take place within a snow co.~x with time have been j described by a number of investigators (e.g., Bader et al.,1939; de Quervain,1945; Kingery,1960).

l It has been shown (e .g., Shepelevsky,1938: Work,1948; Thornthwaite,1950; and Gold,1958) that '

this aging process results in a gradual increase in the snow-cover density as the winter progresses.

This timowiensification process was substantiated in this study on average monthly density values. The computed manthly values for the stations within each category were combined and the results are shown in Figure 3' The density for the stations in Categories 1,2 and 3 (except for 2 between November and January) incre.sses by apptoaimately 0.01 g/cm* each month. The

' decrease in density during December for Ca: egory 2 is believed due to the fact that the stations in l

this group are principally located in a region of heavy snowfall s.ad that the new snow of lighter density that accumulates between November asd January dominates the sucwpack. The stations in Category 4 show little change throughout the winter because their densities are initially near j

mnimum and because they are located at latitudes where be heat derived from solar radiation between December and March is very small and has negligibts effect on snow density. j

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Figure 3. lactease in density from November througin March for Ca'.egories 14.

NOMOGRAPH TO ESTfMATE AVERAGE SNOW. COVER DENSITY One of the main objectives of this study was to develop a nomograph from which the relationship between climatic parameters and the density of winter snow cover could be datermined.

There are a number of fundamental conditions which determine the structure, and physical and mechanical poperties, of a snow cover (Yoeida,1955). In addition to the meteorological environment, other processes directly or indirectly attributable to weather could affect the snow cover. For example, Kondrat'eva (1945) reports that tho sublimatica process is the snow cover can bring about a significant redistribution of snow mass and that a temperature difference of 11 C in a snowpack caused the density in the lower layer to decrease by 0.08 g/cm' in 5 days. The heat flow from the soil and the soil conditions with respect to water content and depth of freezing w .m s , - .. e -

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O O i 6 CLIMATE AND SNOW-COVER DENSITY IN NORTH AMERICA 5 i also may influence the metamorphic processes within the snowpack. Howeve r, these subtle effects and the resultant changes in snow density are not within the scope of this report. These processes and such factors as humidity, radiation and cloud cover must be considered if one wishes to undertake a micro-scale study of changes in snow-cover density.

Dmitrieva (1950) presents a method of calculating the mean density of the snow cover from the following data: the time of snow cover appearance; the number of days with wind speeds over 6 m/sec between the time of appearance of the snow cover and the date of calculation; the sums of positive mean diurnal air temperatures for this period; and snow cover depth or amount of precipitation for cases of heavy snowfall. Dmitrievs states that an accuracy of 0.03 g/cm8 was found in 91% of the calculations for regions where winter temperatures fluctuate little, and least accuracy where frequent thawing occurred. Weinberg and Corlenko (1940) also note that the effect of wind on densif2 cation of the snow cover is important. Wind fragments the snow crystals, causes the finer grains to re-sort, and by packing increases the density.

As Wi111mma and Gold (1968) point out, many dit!1culties complicate the problem of relating snow cover characteristics to climate. For example, in any one area meteorological factors vary from year to year, and the elements measured at a site may not be representative. However, they also found that wind speed and air temperature appear to be the dominant factors in the formation of the cover. Consequently, they developed a weather index using these elearints to estimate average monthly densities. Although there was considerable spread in density for any particular index a correlation did exist between the variables. However, when monthly avetages were calcu-lated for sheltered stations and plotted against the weather index for the month, little correlation i was found.

In Research Report 39 (B11ello,1957) nomographs were developed for estimating average monthly densities. Since that study included only stations north of 62 N1atitude reasonable results were obtained in the month-to-month analysis. A similar approach was tried for the 27 stations in this study, but the results were less fr.vorable. Apparently, the climatic regime under consideration is too extensive for predicting densities from month to month. Therefore, multiple regression analysis was made in which seasonal snow-cover density was related to the average

. air temperature and wind speed (Table I) observed during the same period. The resultant equation derived through the use of a computer is:

p - 0.152 - 0.0031 T + 0.019 W where p - average seasonal snow-cover density (g/cm')

T - average seasonal air tempernre (*C), and F - average seasonal wind speed (m/sec).

The correlation coefficient and the standard error of estimate are 0.84 and 0.025 g/cm8, respect-ively.

By coincidence, the numerical constant (0.152) appearing in the equation is almost identical to that given by Dmitrieva (1950) for the average density of fresh snow (0.15 g/cm'). This value, obtained from two independent studies, implies that when the Arctic, Subarctic and Temperate Zones are considered the average density of freshly fallen snow is higher than the generally accepted water equivalent value of 10".. Figure 4 is the nomograph developed from the above equation.

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vember through March inclusive, unless the average air temperature far the month is above freezing. Ex.

ample: Assame the average seasonal air temperature and wind speed for a location are 12C and 4.0 m/sec.

Extend a straight line through these two points and read 0.265 g/ca' on the snow density scale.

i TEST AND APPLICATION OF THE NOMOGRAPH To test the nomograph, the densities for ten locations not included in the study were E stimated. These stations (Table II: Canadian netwwE Fig; 1) were used because they cover a wide climatic range and their average observed densities were reported by Gold and Williams (1957). Their report, dated 1957, stated that the snow survey was initiated in 1946.

Consequently, average air temperatures and wind speeds for the winter seasons between 1946 and 1957 (Table II) were used as the independent variables (Department of Transport, 1946-57).

Figure 5 shows the observed and estimated densities for these stations. There is good agreemen: between the values (correlation coeincient =0.91) and the standard error of estimate obtained from a least squares computation was 0.016 g/cm'.

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separated at densities of.0.24; 0.27 and 0.31 g/cm*, l The results of density computation from this nomograph gave sufficient conflifence to war-rant its application to a number of stations throughout North America. The necessary climatological data for 10 years of record (between 1952 and 1965) for 61 stations (Table IID were compiled and average seasonM density values were estimated from the nomograph. These values, plus those observed in this nd the Gold and Williams (1957) study, were used to draw an average seasoral snow cover density map for North America (Fig. 6). Using the density ranges of the four categories described previously the continent was divided into zones. The zones were separated at density l

. values of 0.24,0.27 and 0.31 g/cm'.

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9 CLIMATE AND SNOW-COVER DENSITY IN NORTH AMERICA Table II. Observed average snow density, seasonal air temperstare and wind speed for stations in Gold and Williams's (1957) repxt,used totest. nomograph.

Temp Wind speed StarJoe Density) (m/sec)

(g/cm (*C) 0.224 - 10.8 3.7 Edmonton. Alberta 3.2*

0.233 - 8.2

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0.237 Forestvtlle. Quebec -24.7 2.5 Aklavtk. NWT 0.242 0.242 - 13.4 3.5 Moosone e. Ontano 4.0 0.254 -13.9 Whitehorse. Yukon - 7.7 4.7 Ottawa, Ontano 0.275 .

0.279 - 12.6 5.7 Winnipeg, Manitoba 6.8 0.325 -2LS Churchill. Manitoba - 9.8 8.2 Old 'nory. Bnush Columbia 0.369

• Values obtained from nearby stauons.

Table III. Stations for which average snow-cover densities were estimated from nounograph.

j Indian House Lake, Quebec Kotzebue. Alaska l Aishihik. Yukon Mayo Landing. Yukon Arcuc Bay, NWT McMurray. Alberta Baker Lake, NWT Medicine Hat. Alberta Barrow. Alaska Nitchequon. Quebec .

Bethel. Alaska Nome. Alaska Bismarck, North Dakota Norman Wells NWT Brochet. Manitoba North Bay, Ontario .

Buffalo. New York Northway Junction. Alaska' Cache Lake Quebac Notungham Island. NWT Cambridge Bay. NWT Pagwa, Ontario +

Chesterfield. NWT '

Port Harrison. Quebec Clyde. NWT Portland. Maine Coppertnine. NWT Prince George. British Columbia Coral Harbour. NWT Rapid City. South Dakota Duluth. Minnesota Regina. Saskatchewan EnnaAni Lake. NWT Sheridan. Wyoming Fort Chimo. Quebec Sioux City. Iowa Fort Nelson. British Columbia Smithers. British Columbia Fort Reliance. NWT Snag. Yukon Fort Smpeon. NWT Spence Bay, NWT Fort Wayne. Indiana Spokane. Washington i

l Fort Winism. Ontario Summerside. Prince Edward Island Clasgow, Montana Teslin. Yukon j Ctand Praine. Alberta The Pas. Manitoba Creen Bay, Wisconsin Thule. Greenland Hall Beach. NWT Trout Lake. Ontano Harrington Harbour. Quebec Watson Lake. Yukon Havre. Montana l Williston. North Dakota l Hay River NWT Yellowknafe. NWT Holman Island. NWT  :

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i I- 10 CLIMATE AND SNOW-COVER DENSITY IN NORTH AMERICA I

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Gold and Wdliams (1967) divided Canada into five main snowfall regions. In addition to the physical characteristics of the snow cover these regions were determined by the amount of snow-fall, temperature, time of first snowfall, and the length of time the snow stays on the ground.

Except for eastern Canada, their arctic region coincides closely with Category 4 where the highest densities are recorded. Except for some eastern portions and the area around the Great

• • Lakes, Category 3 corresponds roughly with their Northern Forest region. The region they classify as the freeze thaw area, which includes mostly the Atlantic Provinces, southern Ontario and southern Quebec, approximately coincides with the Category 1,2 and 3 areas used in this study.

' As they point out, rain, heavy snowfalls, ice lenses within the snow cover, sleet and above-freezing temperatures are common in this area during the winter. Similarly, the other two regions (1: Prairie zone, and 2: Western Mountain and Coastal zone) covered portions of Canada where areas assign-ed to Categories 1, 2 and 3 are used in this study.

DISCUSSION The system developed in this study provides an estimate of the average snow densin for a general area over a number of years, it does not attempt to predict the density of a snow cover from point to point nor from week to week, nor year to year. Estimated values for 61 locations and observed values for 37 other locations were used to divide North America into geographical areas which fall into one of four preds. fined ranges of density. Except for those areas with snow dens-t

- ities above 0.31 g/cm8 it is shown that the density of the snowpack increases slightly from month

, ,[ to month during winter.

The snow cover and its characteristics are extremely variable in mountainous regions (Alciatore,1916; TSomaia,1966; and McKay,1964). Snowpacks range from permanent snowfields

' at higher elevations to an occasional brief snow cover in the lower and warmer plains and valleys.

Large changes in density that occur in a short distance are exemplified by the mountain station.

Old Glory, British Columbia (Fig. 6). The value for this station places it in Category 4 whereas a station nearby is in Category 1, indicating that the area bridges four categories. The scale of the map and insufficient data preclude the delineation of the intermediate categoriss. Consequently, caution should be used when interpreting Figure 6 in mountainous areas. In some portions of such regicas, where the winter air temperatures and wind speeds over a wide area are reasonably uni-fortr., the results presented in this study are applicable. For example, the stations in Category 1

• in western United States and Canada and the interior of Alaska are mostly sheltered stations in valleys or on the lee sides of mountains where light winds and low densities are consistently observed.

p =

LITERATURE CITED Alciatore. H.F. (1916) Snow densities in' the Sierra Nevada. U.S. Montafy Weather Review, vol. 44, p. 523 527.

Hader. H.: Haefelt. R.: Bucher. E.: Neher, J.: Eckel. 0. and Thams. Chr. (1939) Snow and its metamorphism. Seitrdge zur Geologie der Schweiz. Geotechnische Sene.

Hydrologie 1.ie forung 3. Bern. U.S. Army Snow. Ico and Permafrost Research Establishment (USA SIPRE) Translanon 14.1954. $13 p.

i Bilello M.A. (1957) A survey of Arctic snow. cover propernes as related to ef tmatic condicans. USA SIPRE Researen Report 39,9 p.

de Quervain. M. (1945) Snow as a crystalline aggregate. Experientfa. vol.1. USA SIPRE Translation 21.1954. 7 p. ,

i

. - w m , ------_w .,.- ,_ -~

. N ,

CLIMATE AND SNOW. COVER DEN 5ITY IN NORTH AMERICA 11 D.parunent of Transport. Canada (19461957 and 19521963 Monthly record. Meteorological observauons in Canada. Meteorologtcal Branch. Deparunent of Transport.

Dmitrieva. N.G. (1950) Calculation of snow. cover density using meteorological data.

. Meteorologlia i GJdrologiia, vol. 2. USA SIPRE. Translanon 24.1954. 4 p.

Formozov. A.N. (1946) Snow cover as an integral factor of the environment and its importance. Moscow Society of Naturalists. Moscow, USSR. Boreal Institute.

University of Alberta, Canada. Occasional Paper no.1.176 p.

Gold. L.W. (1958) Changes in a shallow snow cover subject to a temperate climate.

k Journal of Glaciology vol. 3. no. 23, p. 218 222.

and Williams. G.P. (1957) Some results of the snow survey of Canada. Divtsion l of Building Research. Nanonal Research Council. Canada. Re-< erch Paper no.

38. 15 p.

Kingery. W.D. (1960) On the metamorphism of snow. Massachusetts In 2tute of Technology.  !

Ice Research Laboratory Report no. 61 1. 9 p.

Klein. G.J. (1950) Canadian survey of physical charactenstics of snow. covers. Nations!

Research Council of Canada. Technical Memorandum No.15. Repnnted from Glaciers and Climate. Geografiska Annaler 1949. H.12. p.106124.

Kondrat'eva. A.S. (1945) hrmal conductivi'y of the snow cover and physical processes caused by the temperature gradient. Akademala Nauk SSSR. Moscow Leningrad.

USA SIPRE. Translation 22,1954.13 p.

McKay. G.A. (1964) Relationships between snow survey and climatological measurements.

In Surface IFiters. General Assembly of Berkeley. IUGG Publicanon no. 637.p.

214 2?7.

Mode. E.B. (1948) The Elements of Statistics. New York: Prentree Hall. Inc. 378 p.

Rikhter. G.D. (1945) Snow cover,its formanon and propernes. Izdatel'stvo Akademita __

Nauk SSSR. Moscow. USA SIPRE Translation 6.1954. 66 p.

Shepelevsky. A.A. (1938) The distnbution and gradual change of density in snow cover.

• Transactions of the Arctic lastitute for Sefeatiffe Research.110. Translated by Headquarters. U.S. Army Air Forces. Weather Division. Pasdena. California. 24 p.

Thornthwaite. C.W. (1950) Estimating soil tractionability by climatic analysis. Office of the Quartermaster General. U.S. Army Environmental Protection Report No.167. 66 p.

incl. maps.

TSomais. V. Sh. (1956) Methods of calculaung snow density in a mountainous area. Trudy Thatasskogo N..I. Gidrometeorologicheskogu_institzta, vol.1. p. 69 77.

U.S. Air Force (1952 63) Mean monthly wind speeds and mean monthly temperatures for selected stanons. Air Weather Service. Data Control Div.

U.S. Army Snow. Ice and Permafrost Research Establishment OJSA SIPRE) (1954) Instruct.

tons for making and recording snow observations. Instruction Manual 1.10 p.

(revtsed 1962 by USA CRREL). -

U.S. Weather Bureau (1952-63) Climatological data. National Summanes and Alaska Sum.

martes, U.S. Department of Commerce.

Weinberg B.P. and Gorlenko. S.M. (1940) Snow cover and its dynamics. In Ice. Moscow,

p. 410 440.

[ Wengler. F. (1914) The spectfle density of snow. Inaugural Dissertation. Tiedrich-Wilhelms University. Berlin. 86 p.

Williams. G.P. and Gold. L.W. (1958) Snow denstty and climate. Division of Building l Research. Nanonal Research Council. Canada. Research Paper no. 60. 4 p.

Work. R. A. (1948) Snow layer density changes. Transacnons. Amer *can Geophysical Union, vol. 29. no. 4. p. 525 546.

Yosida, A. and colleagues (1955) Physical studies on deposited snow. I Thermal propernes.

Institute of Low Tempersaire Science. Hokkaido University. Sapporo Japan, vol. 7 p.19 74.

V e o ,_

l

• l i . m -

13 APPENDIX A: OBSERVED, WEIGHTED SNOW-COVER DENSITIES (G/CM3 )

FOR STATIONS IN TABLE I.

Extracted, computed and compiled by Roy E. Bates USA CRREL.

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Bealek, fabrador. Ceande (conted) Malmatros an. Creat Felle. Entene (co it'd)

Feb Mar Due Jan Feb Feb kr Joe Nov Dee Joe Feb Mar Nov Dee Jan Feb Mar 1958 1958 1959 3960 196g 1957 1958 1958.g959

.244 .251 .265 353 .212 .26 .230

.410 .155 .176 .189 .200 .15o 3tyl .193 .360 .246

.186 .265 .266 .181 .225 .364 .249 377 .152 .169 .199 .1% .25o .3 91 .158 .283 .249 s

.358 .172 .17f .202 .2 30 155

.178 .21 9 344 .190 - .159

.243 .24o .283 .236 f

.14 .171 .172 .202 .202 .2 37 342 .1 71 .16g

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Nov Due Joe Feb Mar Nov Lee Jan Feb Mar Dee Feb Jon Feb Dee Jan Feb gg

.112 .186 .195 .23) .175 .285 .2W 19 % 1956 1957 1957-1958 .142 .221 .1 A .148 .37

.231 .260 .160 .240 .315 32 .273

.199 .2 67 .244 .145 .192

.200 .190 .224 .169 .12o .235 .211 .147 .271

.283 .224 .29 317 .172 .31

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.225 .241

.247 IN b

.22,8 325 39 a ti:

1957-1958 1958-1959 Jan .W .259 .$3 .M .277 .d .W 357 %

Ev Dee Jaa hb Mar Nov Dee Feb Mar

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.637 31 7

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.206

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.363

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.321 e

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.220 .268 .208 .283 392 .186 348 .284 .2

.236 335

.215 300 .25o

.170

.235

.1 97 36o 353

.191 .4o5 .W 348

.241 .27o .193 .290 .4o5 30

.251 .2 31 .283 .286

.217 .29 1%o-a961 1959-1960

.i 8 . 56 323 .e67 .252 .24o .153 .30 1961-1962 1962. 963 6 . ret 3= .276 .283 .2m .250 .120  ;

353 .260 .26o .294 .26o .248 .265

.2 31

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.2a .26o 8>6 171 98 *"8 "

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Jan Feb Mar Dee Jan Jan hb .1% 5 .1% .135

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.185 .227 .248 .275 .201 .Flo .1&T .224 .19 .1M

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Erv est liarmwa AFB, Newfour iland, Canada .

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• 1M 9-1960 1%3-Ah4 1954-lM5 .253 .Pr) .251 .253 .218

.125 .323 .227 .220 .342 .26:

.300 .232 .385 .180 .rio .240 .222 .246 4Ao .158 .143 323 309 355 .222 .217 .250 .235 .2 52

.212 .159 .2 31 333 .286

.388 .251

.215 .15fl .230

.157 .226 313

)

1960-1961 1961-1962

.282 .253 .2a2 .203 .263 i

.268 .23) .243 .251 .250 .258

.243 .266 .258 286 .206 .239 .265 303 .250

.213 .300 .250 306 .223 1956-1957 3m .243 1 % 5-1956

.o80 .130 .183 .183 .370

.208 .153 .332 .180

.200 .200 000o Day AFD. ImbrmJor. Canada

.3 33

.223

.289 420 Jan Feb Mar 233 Jan Feb Her hv Due

.Nw Ime

.16k 1 % %-1955 1953-1 % 4 .1 71

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.192 .248 .p3 .eJ8 300 .213 .221 34 0 279 g

.160 .153 .2% 253

.400 .283 .238 .p9 .g

.233 410 300 . 31 5 .2'7) . 31 3

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281 .294 317

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.b26 I Jan Feb Mar llow Dee Jan leb br '

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Nov Dec Jan Feb Mar 1954-1955

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.417 .200 .323 e 4:X) .423 388 1955-1956 1956-3 % 7

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.290 37 b .eff .286 .2(1)

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. m APPENDIX A 1" E

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• Porter Isler.l. Alsake Je3 Feb Her Dee Jea hb Jem hb Nor lior Dee Jan Feb Her Now tae Jan Wb Her g 1963 1961 1961-19 0 1962 1963 1952 1953 3933.s 9A

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.243 . 31 4 350 333 .453 , .237 3% 329 .236 .192 311 .286 304 373 .398 .400 334 325

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. 343 .276 .238 .296 300 . 31 2 34t .408 .261 .2%

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.258 .292 .293 .2 81 .298 .3:x .300 318 .264 .240 34 8 360 .354 355 32 .

.2% .266 303 318 37f .2To .283 336 .294 314 361 361 35] .34 6 .382

.290 361 .%t 356 36b . 1412

. .411 359 3% 356 369 .61 6 355 WrtemItb AFB, Oscade. Michlaan Feb Mer Dee Jan Jan Feb Her Nov Doc Jan Feb 3'o r llow Dee Jan Feb Mar i 19 % 19%.1955 1958 1959

.256 .250 .4%3 .23 6 .p3 .275 323 1951 19'32 1953 19 % g

.217 .216 31 2 .288 .260 .252 .415 378 431 34 5 . 372 34 2 34 5 381 g

.240 .333 .260 357 340 37) .422 373 369 363 3(2 396 g

, .252 31 3 394 361 347 356 388 tej

. .262 34 5 35o .y4 353 *ic 4 .261 345 .O 9

!9%-t955 1955 t956 N

l Nog Dee Jan Feb Her liow Dee Jer* Feb Mer 351 371 356 336 383 259 363 330 336 346 b

} 369 383 355 321 .%b 355 363 353 351 ,352 1959-1963 1960 1961 322 3tA 361 372 339 333 311 .367 352

.233 340 .y;8 341 .273 .253 .210 .%7 336 .%7 349 363 323 362

.280 422 .410 383 .45 .140 .240 361 357 .Wo 361

.410 372 381 316 .174 351 I .200 .334 333 31 6 355 1956-1957 1957-19';8 .I

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.212 .873 .pb 327 31 9 331 .2*>2 .248 339 361 .438 333 .308 315 .291 322 .2% .258 332 371 .43o 1968 1962 1962-1963 336 .274 .261 362 .262 .261 32 1 .41 6 389

.17% .290 304 .200 .280 300 .213 .2% 382

.228 380 351 .15o 300 .350

.263 .253 .390 320 300 .450

.212 .209 .600 .240 .450 1958-1959 1959 196a 300 .293 .2 5 .254 .2 7 .255 .277 .186 .260 301 314

! .2 3 .257 .2 7 .272 .277 .204 .268 .2 38 32o

.252 .273 Cape f.taburne APJ, Aleeke .258 .26%

. .259 Nov Dee Jan Feb Mar Hov Dee Jan Feb Her 1961 1962 1962 1963

. .271 .366 .422 .3% 400 .2% .290 .290 34T .223 310 350 .353 . 311 36h 32o .283 .240 344 .267 i

342 .400 .290 .298 i

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e 196t.1962 1953.i954 19 A 955 19 6 1964 .20) .2t9 .N1 .204 .3T2 359

• .286 336 .293 .275 322 322 330 363 .203 .146 338 332 .184 535 .296 .273 .352 .295

.282 .298 .295 .293 353 .222 365 37n 363 .166 .472

.31 3 343 331 .368 359 332 337 8

.32 335 33 37 2 32T

.283 .406 Nov Due Jan Feb Mar l

1962 1963 1955 3956 1936 1w7 4

)

.y8 383 .386 .360 .be .not .440 .415

.242 .22b .29T 303 .)To 37 4 34%

.418 .430 . 38 7 .4 .%t9

.232 369 35o .284 362 .%of .et2 .p59 394 .324

.6 3 .402 8 .351 .278 385 436

.ko8 31 414 38 6 39 .461 32r 384 37 6 . tor .372 .339 4o5 8 ,334 382 .440 Nesolute, m . Canoaa 30 Jan hb Mar Nov Dro Jon Pob Mar Nov Dee 19A1959

' 1957 1958

.387 .322 .329 357 .329 .323 .341 .M4 1953-195% 300 384 1952 1953 308 .292 .284 .321 .P .208 .266 .263 .322 .337 399 367 .29c .$7 331 e

.275 336 349 365 .256 424 338 g

.360 .332

.283 374 358 330 251 327

. 31 0

.276

.27r 306

.352 350

.360

. 311

.283

.361 332

.406 368 331

.328 .423 362 281 g .

T

.n2 306 352 374 31 6

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1960-1961 1954-1955

.308 1955 1956

.37 o 336 .346 .268 .272 1959 1960

.360 .266 .242 .yn 329 3t3 344 .323 2 3ot .321 .332 304 .329 371 360 .288 . 31 6 .400 .31 2 312 327 367 M 1 325 34 3 355 .335 301 333 .203 327 3o5 315 326 314

.317 356 360 350 .yr 31o 367 .331 x I 3m .346 322 308 334 397 355 368 36b j .370 328 31 8 335 324 325 334 335 335 353 3o6 1961.962 1962-1963

,ygt 383 .405 .264 329 363 38) .367 1956 1957 1957 1958 340 346 .317 h

.290 . Fro .689 439 357 .271

.380 .382 .393 3 62 394 .260 350 330 1

.240 .250 .452 .275 359 .

37T .419 371 37f 347 .310 . 31 0 341 t 394 31 6 300 340 .}20 . 31 0 .190 1 387 396 324

.268 .420 426 3M .415 320 .31 0 .350 341 300

.295 Hauta moy, m , consa.

.k21 99 .250 330 31 0 Dee Jan Feb Mar Nov Dee Jan hb Mar Nov 1959 1960 1960-t961 1954.1955

.448 .366 340 309 .323 1953.ns54 .hth 415 300 365 395

.252 355 .27f .27f 3e .305 .290 .k28 .hof .391

.bl8 368 .4o8 363 368 31 1 314 .349 .420 .kt5 .ko1 .4f2 401 396 31 6 .323 304 .410

.437 .405 .292 .287 .291 .309 429 409 364 364 337 .291 .433 .k21 3'XI .404 354 336 37) 1961 1962 1962 1963

.381 .372 374 380

.254 364 361 1955 1956 e 1957 1958

.247 460 357 .433 37b 387 .W4 8 .415 320 37 3 361 .341 .404 382 .317 31 3 35 .37 5 356 361 .yi8 .kor 387 .401 358 318

.poo 359 .31 5 338 345 3% .395 .447 383 .267

.=13 369 375 369 -

329 358 388 362 366 327 459 .4 31 353 a399 353 314

• e Mould Iey, IRM. Conede (coet'd) e flow Dee Joe Feb Mer liev Dee Joe Feb Mer to O

1958-1959 1960-1961

.247 301 .260 327 349 390 .290 .422 349 .359

.271 304 317 .2 63 .350 .256 32 8 306 352 331

.285 309 ,

.294 .255 tiov lae Jan Feb Mer

/

1961 1962

.303 403 .403 .360 313 328 .ps 348 401 378 g

• Teachsen. IAM Conede Nov Dee Jan Feb Mer How Dee Jan Feb Beer 1952 1953 1953 1954

' 309 339 .314 355 392 .401 .420 401 .4o1

.p .4o9 .435 .4 31 424 305 .311 333 358

.359 .350 .eu .4M .4;6 .420 424 308 358 328 409 .4%) .418 .k38 430

.373 377 A

• u

• o 1953 1956 tre 1954 1955  !<

l .420 369 428 .408 372 .

s

.ho

.37 5

.m 351 .335

.m .297 4o3 413 393 e I i .

.34 0

.361 336 400 627 3rr .438 406 453 .458 425 y e f.

l .k20 .330 .406 .403 340 e.318 b 352 323 1956-1957 1957 1958 322 324 . 34 8 329 383 37 8 31 0 324 308 31 3 336 309 394 366 g

- 357 311 .N1 347 .377

) 34 6 .400 ,_399 . bot 32 6

I 374 368

?

1958-1959 1959 1960

! .248 .267 34 0

.247 .292

' .212 .276 .252 332 342

.264 334 .418

• . 37 3 a

9 1960-1961 1961 1962 .

.200 .3o6 .283 344 32o 315 325 .413 393

.256 333 .319 34 6 31 9 .350 399 .473 ,

Ilow Dee Jan Feb Mar ,

1962 1963 '

a f* .N1 .355 .hte

.342 .40}

31 8 .366 .412 31 0 31 6 i .

,-.s..

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thelassified I U.S. Ar::r Cold Regions Research *"***

l. 3r Engineering Iaboratory Ranover. New Hamtshire 03755 t 8. A SPO ft ? TI Th.E REATIC:ISHIIS BE'I"4EE:t CWATE AND RT,IONAL VARIATIC::S ET SNCWCCVER DE::SI'"Y

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1, ET NCR'JI AMERICA oeocneevsya s.o7as (Typ. . e.p.rs d m J e see..)

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Michael A. Bilello J.AEpQst? O.73 7a 707 4.s.0.OPpaeES Th. 8e0. O F R E F S December 1969 23 26 c a . .c r . . ... r ... ...... . r o a s a s.o a r w.<.s a

a. ===oser ao. DA Task l?J"611C2352Ac2 Research Repert 267

s. ee. o f.e Pon t mots. ga.r .an.r _ an.e m.y a. se e nt, s o. oe s t ne ou view o f. T aa.as. T

'Ihis document has been approved for public release and sale; its distributien is = 14=4ted. ,

... .. .. .., v.. i .. .... v .. , .c ri vi r, U.S. Ar=y Cold Regions Research

& *g*naering Iaboratorf Hanover, New Ha=eshire 03755 64..esfA.GT Analysis of sucv-cover observations made during Nove=ber - lhrch at 27 stations in Alaska, rnnda and the ncrthern Thited States for a 2 to 11 year period showed that the average snow density can be classified in four general categories: Categerf 1 (density 0.2 to 0.23 g/cm3), inlana to 0.27 g/cmg), stations reporting moderate vinds; Category 3 (0.28 to 0 30 g/e=statien

' inlana and ccastal locations with strccger winds; Category 4 (0 32 to 0 36 g/cm3),),

cold and vindy stations of the Arctic. Skevness coefficients ccmputed for each static i showed bias toward lower densities for cat. 1 and 2, and bias tcvard higher densities for cat. 3 and 4. A nemcgraph in which the average vinter air temperature and vind speed are the independent variables makes it possible to estimate the average snow-cover density for any locatien in the Arctic, subarctic and North Temperate Zenes. A l comparisen between observed and esti::nted densities for ten other test stations yiel4ed a correlation coefficient of 0 91 with a standard error of estimate of 0.016 g/cW. An average ancv dsnsity map of North America was drawn and the centinent was o divided into areas based en the four categcries.

14. KEY WORIE t

Cli=atolcgy Sncv cover Snow density

-= r ***n ee.. . se DD , Peen ,,,, ,,'] 4 =/ me.s.s o .a css oo .. .,8.re.e r s e.= ver. s thclassified security Claestacause

-.amosum M. "O w *

. , Md REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS) ,

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