Geoscience Reference
In-Depth Information
Table 8.1
Equilibrium line attitude (ELA), annual accumulation, and solid precipitation for
various mountain and upland regions in Eurasia
Mean ELA
Accumulation
Solid Precipitation
(m.)
(mm water equivalent)
(mm water equivalent)
Franz Josef Ld.
260
300
300
Novaya Zemlya
480
610
610
Polar Urals
850
1,700
1,060
Sev. Zemlya
450
230
200
Byrranga Mts.
850
330
210
Source
: From Glazovsky (
2003
).
The range is about 100 km wide in the Polar Urals (north of 64
o
N) and 300-400 km
in the Middle and Southern Urals (59-51
o
N). In the Northern Urals (59-64
o
N) annual
precipitation totals reach 700-800 mm on the western slopes, while amounts are some
100-150 mm less on the eastern slopes. Amounts decrease northward in the Polar
Urals sector to 500-600 mm. In northeastern Siberia, valley glaciers occupy some
200 km
2
in the Suntar-Khayata Range (62
o
N, 142
o
E), which rises to 2,500-2,900 m.
Annual precipitation, falling mostly in summer, is 500-700 mm on the western slopes
at about 2,000 m. Further to the northeast, in the Chersky-Momsky Mountains (2,500-
3,100 m), there are mainly cirque glaciers. Here the regional snow line (the average
lower elevation limit of snow persisting throughout the year) is around 2,200-2,300
m. Precipitation increases from 400-500 mm in the northern ranges to 800-1,000 mm
in the southern areas. Nevertheless, rock desert is widespread above about 700 m
in the north and at 1,000 m at latitude 62°N. There are extreme climate contrasts
between valley bottom and ridge top sites in this area. In winter, intense inversions are
associated with frequent cases of surface air temperatures below −60°C.
In the Eurasian Arctic the equilibrium line altitude (ELA, the altitude on a glacier,
ice cap or ice sheet for which annual mass gains equal annual mass losses) shows
a general northward decrease from 600-1,000 m above sea level in the Polar Urals
and Byrranga Mountains to 480 m in Novaya Zemlya, 450 m in Severnaya Zemlya,
and 260 m to only 150 m on some of the islands of Franz Josef Land (
Table 8.1
).
The mean precipitation listed in
Table 8.1
masks strong regional variations. For
example, differences in solid precipitation between the windward and leeward sides
(with respect to the prevailing winds) are 240 mm on Franz Josef Land, and 600 mm
on Novaya Zemlya.
8.6
Urban Modifications of Local Climate
8.6.1
Heat Islands
Urban heat islands (UHIs, which can be defined in terms of the surface air tem-
perature in an urban area relative to that in surrounding undeveloped areas) are
