batch_auto_20260713 202607131256465730 BOEM ESP geoESPIS ESPIS@boem.gov Bureau of Ocean Energy Management Western Beaufort and Chukchi Sea Surface Current Analysis University of Alaska Fairbanks University of Alaska Fairbanks We processed and analyzed six years (2013 – 2018) of surface current data collected by high-frequency radar (HFR) systems on the coastlines of the western Beaufort and northeastern Chukchi Seas and derived surface flow patterns based on 362 days during the open water season. Maps of vorticity and divergence are presented as averages and as a function of wind speed and direction. Flow convergence occurs where the Alaska Coastal Current meets the Beaufort Sea coastal flow in the middle of Barrow Canyon, at the head of Barrow Canyon, and near the mouth of Barrow Canyon. Flow divergence occurs over the northwestern Beaufort shelf within and west of a small canyon at 153 ?W. A recurrent gyre forms at the site of this divergent flow. The gyre straddles the shelf and slope region, normally rotating in an anti-cyclonic (clockwise) fashion during strong northeasterly winds, but relaxes when wind forcing is absent or weak. The gyre appears to be a consequence of the Alaska Coastal Current flow through Barrow Canyon, the prevailing wind, and the coastal constraint on the western Beaufort shelf.\n Oceanographic moorings that measured subsurface currents were analyzed in conjunction with the HFR data to assess velocity shears in the upper 10 m of the water column. While the HFR-based currents are similar to the water column average flow, there is appreciable shear in speed and/or direction as a function of the relative orientation between the surface wind and the underlying currents.\n The complexity of the flow field in this region precludes simple wind speed/direction-based estimates of surface drift and has application to oil spill trajectory predictions. 77640 U.S. Department of the Interior, Bureau of Ocean Energy Management, Environmental Studies Program https://doi.org/10.13039/100012475 M20AC00001 10.67297/9A1E3A https://boem.gov/awardpages/100282