Table 1. Average temperature (C) at various Alaska
would be of little concern. On level ground, snow
sites (19481990). The data are derived from the Inter-
density has less effect; the depth of snow is the
national Station Meteorological Climate Summary (U.S.
major concern in this case.
Navy, U.S. Air Force, Dept. of Commerce 1992).
Snow depths are difficult to characterize, since
they vary greatly according to the microclimate,
Nov
Dec
Jan
Feb
Mar
Apr
microgeography, aspect and vegetation cover
Anchorage
5.6
8.9
9.4
7.8
3.9
2.2
(open or forested). Open sites tend to have lower
Barrow
17.8
23.3
24.4
26.7
25.0
17.8
snow depths, because the higher winds in open
Bethel
5.0
10.0
10.6
10.6
6.1
0.0
areas tends to compact the snow more. The snow
Big Delta
13.9
19.4
20.0
16.7
10.6
1.1
Fairbanks
15.6
21.1
22.8
19.4
11.7
0.6
in the forested areas is also colder than the snow
Kotzebue
12.8
17.8
17.8
19.4
17.2
11.1
in open areas, which means that there is less melt-
ing of the outer surfaces of the ice crystals in the
snowpack, slowing down the compaction and set-
Table 2. Average wind speed (m/s) at various Alaska
tling process.
sites (19481990). The data are derived from the Inter-
The greatest snow depth measured in a forested
national Station Meteorological Climate Summary (U.S.
Navy, U.S. Air Force, Dept. of Commerce 1992).
site at Fort Greely was 116 cm, and the greatest
snow depth at the open site was 50 cm. The Fort
Nov
Dec
Jan
Feb
Mar
Apr
Greely study did not address the issue of drifting,
Anchorage
2.78
2.68
2.83
3.04
3.04
3.19
and the snow depths are determined by taking the
Barrow
5.92
5.25
5.35
5.09
5.09
5.20
average of snow courses set out over a relatively
Bethel
5.35
5.76
5.97
6.28
5.81
5.35
wide area. A worst-case value for the maximum
Big Delta
4.37
5.40
5.61
4.73
4.22
3.40
seasonal snow depths at Fort Greely would be
Fairbanks
1.59
1.34
1.39
1.75
2.32
2.83
approximately 125 cm. A slightly higher figure
Kotzebue
6.28
6.02
6.28
5.92
5.30
5.35
should be used for higher-precipitation areas in
interior Alaska.
Table 3. Average sea-
sonal snow density
The Fort Greely study cites an earlier study by
(g/cm3) at various
Bates and Bilello (1966) where an empirical rela-
Alaska sites calculat-
tion between air temperature, wind speed and
ed using eq 1.
snow density was derived:
Location
Density
R = 0.152 0.0031T + 0.019W
(1)
Anchorage
0.225
Barrow
0.323
where R = average seasonal snow cover density
Bethel
0.283
(g/cm3)
Big Delta
0.282
T = average seasonal air temperature (C )
Fairbanks
0.235
Kotzebue
0.313
W = average wind speed (m/s).
Table 4. Cumulative snow density (g/cm3) at
This equation was taken from measurements for
various Alaska sites calculated using eq 1 and
Alaska, the northern contiguous United States
a weighted-average technique.
and Canada. It presumably should be limited to
Nov
Dec
Jan
Feb
Mar
Apr
these relatively cold areas.
We next apply this equation to a few stations in
Anchorage
0.222
0.230
0.235
0.234
0.222
0.206
Barrow
0.320
0.324
0.329
0.331
0.326
0.306
Alaska. We will assume that the snow season runs
Bethel
0.269
0.292
0.298
0.304
0.281
0.254
from the beginning of November through the end
Big Delta
0.278
0.315
0.321
0.294
0.265
0.220
of April. The average temperatures at these sites
Fairbanks
0.231
0.243
0.249
0.246
0.232
0.207
over the period of record (19481990) are shown
Kotzebue
0.311
0.321
0.326
0.325
0.306
0.288
in Table 1.
The average wind speeds over the same period
are shown in Table 2. Using these data and eq 1 re-
from November through the month in question
sults in the estimates of average snow density
and then using a weighted-average technique to
over the whole season shown in Table 3. Equation
remove the previous month's estimated value
1 can also be used for estimating the average den-
(Table 4).
sities for each of the months of the snow season by
A somewhat less complicated approach to es-
estimating the snow density for the entire period
timating monthly snow densities is found in a
2
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