south of the Novosibirskiy Islands, which are only
serious concern to navigators in the Barents at any
13 m and 8 m deep, respectively. These extreme
time.
shallows limit the size of ships that can pass safely
to those under 20,000 dwt unless they are spe-
The Kara Sea
cially designed for shallow-water operations
The other seas along the Russian coast are in-
(Wergeland 1991). The more northerly routes are
fluenced by cold continental air masses and hence
deeper, but ice conditions are also more severe.
experience much colder air temperatures than the
Barents. Mean winter temperatures range from
15 to 20C in the southwest Kara and from 25
The Barents Sea
to 30C in the north and east Kara. Mean summer
The Barents is the warmest of the Eurasian seas,
air temperatures range from 0 to 5C. The sea ice
and the only one not totally ice-covered in winter.
During the most severe winters, only about 90%
cover is greatly influenced by its relatively land-
of the surface is covered with ice (70% and 50% in
locked perimeter, winds, river runoff, and shallow
normal and mild winters, respectively). It experi-
bathymetry. Due to Novaya Zemlya, there is little
ences the greatest seasonal variation of sea-ice ex-
exchange of warm water from the Barents. Like-
tent. Its ice cover is dramatically affected by the
wise, Severnaya Zemlya inhibits exchange with
influx of warm water from the Atlantic, which
the Laptev Sea. Water and ice mass exchange is
moderates the ice conditions in the southern and
almost entirely with the Arctic Ocean to the north.
southwestern Barents. General ocean circulation
Fast ice forms along the entire Kara coastline,
and prevailing winds in winter advect ice south-
and it is generally narrow, except in the eastern
westward from the northern Barents ice pack. The
Kara where it extends outward for 80 to 110 nm.
southern Barents in winter, however, experiences
Throughout fall and winter, the only substantial
generally southwesterly winds that introduce
openings in the ice cover usually occur at the
warm maritime air and inhibit ice growth. Winter
boundary between this fast ice and the outer pack
mean air temperatures are relatively mild (10 to
ice. Offshore winds tend to push the pack away
15C). First-year ice thickness averages 50 to 100
from the stationary ice, creating occasional lanes
cm in the south and 120 to 150 cm in the north.
of newly forming ice. This transport mechanism
Severe winter conditions are the result of occa-
produces thicker ice to the north. The coastline at
sional shifts in the normal positioning of the Ice-
the eastern end of the Kara is about 400 nm farther
landic low and Siberian high pressure systems,
north than at the western end, resulting in cooler
which cause southeasterly winds to dominate. Such
air and sea conditions in the eastern sector. The ice
a shift brings in cold continental air off the Sibe-
thickness in a normal winter ranges from 120 cm
rian plateau, which gives rise to greater ice pro-
in the southwest to 200 cm in the northeast.
duction in the southern Barents.
Summer melting in the Kara typically begins at
The protection offered by the perimeter loca-
the outer edge of the fast ice when ice production
tion of the major island groups of Svalbard, Franz
ceases. A few weeks later the fast ice breaks free
Josef Land, and Novaya Zemlya prevents the in-
and drifts seaward. Rivers flowing into the Kara
flux of ice from neighboring seas where ice pro-
constitute more than half of all the runoff entering
duction is greater. In addition, weaknesses in the
the Eurasian seas. Warm spring runoff produces
ice cover are prevalent on the leeward side of most
early open-water areas at the major estuaries, and
island groups in the Barents. Prevailing easterly
by midsummer, the western Kara is normally ice-
free as far north as 75N. There may be open water
winds continually drive the ice offshore so that ice
as far north as 82N during a mild summer. There
that is present at any time is newly formed and
relatively thin. These lee-side polynyas are gener-
is, however, a cold ocean current running south-
ally evident throughout the winter off Nordaust
ward along Novaya Zemlya that piles ice into the
Land, Kong Karls Land, Kvitya, Novaya Zemlya,
Kara Gate. This ice often survives through an un-
and especially Franz Josef Land. The springsum-
usually cool summer.
mer melt pattern usually initiates and expands
In the eastern Kara, summer melting is less ex-
from these areas. During summer, the polynyas
tensive; nearly half of its area remains ice-covered
typically expand southward to meet the northerly
throughout a normal summer. The year-to-year
retreating main ice edge, forming vast tongues of
variability, however, ranges from 0 to 80% cover-
open water. In a normal summer the ice edge re-
age. In addition to a more northerly latitude, warm
treats to about 78N. While all the major islands
river inflow is dramatically less here than in the
have actively calving glaciers, icebergs are not a
western Kara. There is no prevailing summer wind
26
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