Nearshore ice characteristics in the eastern Bering Sea

Abstract

A description of Bering Sea nearshore ice conditions is presented based on compilation of fast ice edge satellite data, and observations of specific ice events and results from other studies. Landsat imagery at 1:500,000 scale was used to map Bering Sea ice conditions between 1973 to 1976 in nearshore areas. From these maps, secondary single attribute maps were compiled, giving the edge of fast ice at various epochs during these four years. Maps were then compiled on a seasonal basis representative of 1) midwinter, 2) late winter - early spring, and 3) mid-to-late spring. The seasonal average maps were then compared to determine seasonal trends in fast ice edge location. This information was analyzed together with imagery showing specific ice events and bathymetric charts, wind data, tidal variations and observed ice trajectories. The result is a regional description of average nearshore ice conditions along the Bering Sea coast from Cape Prince of Wales to Cold Bay on the Alaskan Peninsula. Over this distance a north-south transition is found from fast ice conditions similar to those in the Beaufort and Chukchi Seas (fast ice bounded by grounded ridge systems located at 20 meters depth), to conditions generated by large tidal variations, offshore winds and highly mobile ice, with the result that fast ice is found only in highly protected, shallow waters.