Michael J Karcher and Josef M Oberhuber (2002)
Pathways and modification of the upper and intermediate waters of the Arctic Ocean
J. Geophys. Res. 107(C6).
The purpose of this study is to investigate the pathways and the ventilation
of source water masses of the upper and intermediate waters of the
Arctic Ocean. For the Arctic and subarctic domain a coupled ice-ocean
general circulation model is set up to be integrated for several
decades. It is driven by a climatological seasonal cycle of monthly
mean atmospheric data from 1980 to 1989 and by restored sea surface
salinities. Passive tracers are used to visualize and interpret the
modeled flow and to compare it with observations. The model is able
to reproduce known features of the Arctic Ocean circulation like
the inflow of two branches of Atlantic origin via the Fram Strait
and the Barents Sea and their subsequent passage at middepths in
several cyclonic circulation cells. The fate of these Atlantic source
water masses, river water, and Bering Strait inflow water in the
model are studied. The branch crossing the Barents Sea is subject
to an intense heat loss and ice formation. As a result, water of
this branch leaves the shelf toward the central part of the Arctic
Ocean not only at the surface but also in denser varieties, which
finally feed the central Arctic at halocline and middepths. The lightest
part turns northward and finally westward joining the Transpolar
Drift; the densest part (200–1000 m depth) moves eastward along the
continental slope. A similar path is taken by the Atlantic water
branch from the Fram Strait. The inflowing branch over the Barents
Sea turns out to be the dominant source for the lower Atlantic Water
layer in the Arctic Ocean in this investigation. Atlantic tracers
starting in Fram Strait need 6 years to reach the northern Laptev
Sea slope. Travel times to return to Fram Strait are 15–20 years
along the Lomonossov Ridge and about 30 years along the continental
slope of the Canadian Basin. Tracers that mark the Pacific Water
or the Mackenzie River Water flow eastward and leave the Arctic mainly
via the Canadian Archipelago. The Siberian River water tracers at
the surface penetrate far into the Canadian Basin before they join
the Transpolar Drift. The travel times of the river water from the
river mouths are 2–3 years to the shelf edge and 12–14 years to Fram
Strait.