Circulation and transport of water along the western Weddell Sea margin

Authors

  • Robin D. Muench,

  • Arnold L. Gordon


Abstract

Ocean current, temperature, and salinity data obtained from the western Weddell Sea during the austral winter 1992 U.S.-Russian drifting ice station experiment Ice Station Weddell 1 (ISW-1) are used to describe water circulation and transport. Surface-to-bottom baroclinic currents were computed by applying the geostrophic approximation to derived density data. These were corrected using current measurements obtained from drifting current meter arrays, and the resulting total currents were vertically integrated to obtain volume transports. Transport was found to be northward in the region, which encompassed the western boundary current of the cyclonic Weddell Sea gyre. This northward transport increased from south to north by more than a factor of 2, from about 12×106m3 s−1 in the southwestern Weddell to about 28×106m3s−1 farther north. The increase in northward transport was compensated for by westward flow from the interior of the gyre into the western boundary region. About 5–6×106m3s−1 of the northward transport was contained in a 300–500 m thick bottom layer of cold water. This layer, whose transport increased by about 1×106 m3 s−1 from south to north, was identifiable by its water mass characteristics as Weddell Sea Bottom Water originating on the southwestern and western shelf regions. Its north flowing volume was consistent with past estimates of a 1.5–2×106 m3 s−1 production rate coupled with a 300–400% transport increase due to entrainment during downslope flow from the shelves to the deep basin. The maximum (northernmost) northward transport, less the bottom water transport, is consistent with previous estimates for wind-driven transport in the Weddell Gyre provided that bottom friction and the sea ice influence on wind forcing are taken into consideration.

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