The Bering Slope Current System Revisited

Abstract

Mean circulation and water properties within the Aleutian Basin of the Bering Sea are investigated using hydrographic and subsurface park pressure displacement data from a regional array of 14 profiling CTD floats. After 10 days drifting at 1000 dbar, each float measures temperature and salinity profiles as it rises to the surface and then transmits these data via satellites, which also make several fixes of the float surface positions before it sinks again. Every fourth cycle, the floats sink from 1000 dbar to a 2000-dbar target just prior to ascent to measure deeper profiles. The 1000-dbar displacements estimated from the float surface position fixes reveal a coherent few-centimeters-per-second northwestward flow along the northeastern boundary, the deep signature of the Bering Slope Current. Middepth water property distributions are consistent with cyclonic advection of warm water from the south around the basin, eastward in the Aleutian North Slope Current, and then northwestward in the Bering Slope Current. Geostrophic transport estimates relative to 1000 dbar also show cyclonic motion, although with significant noise, likely owing to the influence of mesoscale eddies. The mean along-slope geostrophic transport of the Bering Slope Current is determined between 0 and 1900 dbar relative to 1000 dbar and then combined with mean along-slope velocities at 1000 dbar. The result is an absolute geostrophic transport estimate with 95% confidence intervals for the along-slope current offshore of the 1000-m isobath and between 0 and 1900 dbar of 5.8 (±1.7) ? 106 m3 s?1.