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CIRCULATION
AND OUTFLOWS OF THE CHUKCHI SEA
Rebecca Woodgate
(UW), Knut Aagaard (UW), Tom
Weingartner (UAF) |
 N00014-99-1-0305  OPP-0125082 With thanks to the US Coast Guard for ship support Back to High Latitude Dynamics |
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CIRCULATION
AND OUTFLOWS OF THE CHUKCHI SEA
Rebecca Woodgate
(UW), Knut Aagaard (UW), Tom
Weingartner (UAF) |
N00014-99-1-0305 OPP-0125082 With thanks to the US Coast Guard for ship support Back to High Latitude Dynamics |
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CHUKCHI SEA BASICS The Chukchi Sea, ~
500 km wide (east-west), ~ 800 km long
(north-south), is a shallow (~ 50 m deep)
shelf sea just north of the
Bering Strait and south of the Arctic Ocean proper. It is fed
from the south by the Pacific water throughflow through the Bering
Strait. Patterns of ice melt suggest the mean flow (which is
northwards in the annual mean) is split into four main outflows - one
through Barrow Canyon in the east, one through the Central Gap in the
Central Chukchi Sea, one through Herald Canyon, just east of Wrangel
Island, and one through Long Strait, between Wrangle Island and the
mainland of Russia. There is also a seasonal current, the Siberian
Coastal Current, present some years, flowing south through the Long
Strait. For a full description of the flow structure see "A year in the Physical Oceanography of the
Chukchi Sea".
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The
Chukchi Sea, being fed by nutrient-rich waters from the south, is one
of the most abundant marine ecosystems in the world, including whales
and walrus,
Waters from the Chukchi are an important source of nutrients, heat and freshwater for the Arctic Ocean. The nutrients support Arctic ecosystems. The heat can influence the ice. The freshwater can stratify the Arctic Ocean, and protect the ice from the warmer Atlantic waters below. Thus, the pathways of Pacific waters in the Arctic may affect the Arctic system. Globally, the freshwater throughflow is an important part of global water cycles. |
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Between
1990 and 1991, an extensive mooring project took place in the Chukchi
Sea, in conjunction with joint US and Russian Cruises. Year-round
moorings measured water velocity, temperature and salinity on 3 major
sections - one across the Bering Strait, one across the central Chukchi
and one across the major outflows of the Chukchi in the Arctic (i.e.
Barrow Canyon, the Central Channel, Herald Valley and Long Strait). The data showed the Chukchi Sea to be strongly driven by the wind, but suggest that other than a cooling, there is little net change in salinity of waters as they pass through the Chukchi Sea. For more details, see "A Year in the Physical Oceanography of the Chukchi Sea". |
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The SBI (Shelf Basin Interaction) Program,
sponsored by NSF and ONR is a multidisciplinary program to study
physical, biological and chemical processes over the Chukchi Shelf,
with a view to elucidate key shelf-slope-basin processes, which are
relevant to local and Arctic climate.
The initial phase of the program consisted on the analysis of historic data. Phase II of the program was the field phase from 2002 to 2004, with up to 3 ice-breaker cruises a year, to study processes in spring, summer and autumn. Phase II also supported year-round moorings. One mooring project (Weingartner, Aagaard, Woodgate) focused on the outflows from the Chukchi Sea, measuring in Barrow Canyon, the Central Channel and (since Herald Valley is in Russian waters and no EEZ permission was available) at two sites on the northern Chukchi Slope. The second mooring project (Pickart) deployed a high resolution section of moorings on the Beaufort slope east of Barrow, to study the dynamics (especially eddy formation) of the Pacific waters flowing eastward along the northern coast of Alaska. For more details see, SBI Healy 2003 Mooring Cruise. |
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