Modeling winds and open‐water buoy drift along the eastern Beaufort Sea coast, including the effects of the Brooks Range

Abstract

The United States Coast Guard deployed a cluster of satellite‐transmitting, surface‐drifting buoys in the Beaufort Sea north of Prudhoe Bay, Alaska on August 17, 1983. The surface currents in this coastal area are predominantly wind driven. An unusual stand of westerly winds led to eastward drift with the surviving buoys moving into Mackenzie Bay (Canada) by mid‐September. The buoy motion suggested that they were driven by the geostrophic wind modified by the orographic “umbrella” of the Brooks Range. This mesoscale effect can create changes in wind direction and regions of super and subgeostrophic speeds. It influenced an arcuate zone at least 50 km seaward of the coast from Camden Bay (Alaska) to Mackenzie Bay. A simple model was developed to predict the wind modifications and resultant wind‐driven buoy drift. The model's initial wind velocity input is a calculated geostrophic wind derived from triangular‐shaped mesoscale atmospheric pressure network data. These networks were chosen because their boundaries alternately contained the trajectories of the eastward‐moving buoys. The model then used this network velocity to generate an orographically‐modified wind field at buoy locations in offshore areas north of the Brooks Range. The actual buoy drift during the open‐water season covered approximately 650 km in 60 days with the final model‐predicted buoy drift position in error by less than 50 km. The Brooks Range influence did not appear to affect the October buoy drift which was north of Richards Island (Canada) above 70°N and east of 135°N.