Surface Currents on the Northeastern Chukchi and Western Beaufort Sea Shelves as Detected by High Frequency Radars

High-resolution high-frequency radar (HFR) measurements of surface currents during the open water season in the northeastern Chukchi Sea and, more recently, the western Beaufort Sea have revealed enormous spatial and temporal complexity in the surface circulation. This variability is associated with the Alaskan Coastal Current within Barrow Canyon and its interaction with the flow over the western Beaufort Sea shelf, as well as eddies and fronts over the Chukchi Sea shelf.

In the Chukchi, HFR suggests a front along 71.5°N, that likely separates summer Bering Sea water from ice meltwater that has not been entirely flushed from the region. North of the front the water column is heavily stratified, and the circulation is typically weaker and more variable in direction than the more easterly (and less stratified) flow south of this latitude. This eastward flow feeds central shelf waters toward Barrow Canyon and appears to persist even under westward winds that are <6 m/s. Moored data suggest that the HFR measurements reflect flow throughout the water column in unstratified areas, while in heavily stratified regions, the HFR velocities are a good proxy for flow in the upper 20 m of the water column occupied by the meltwater.

At the juncture of the Chukchi and Beaufort seas the northeastward Alaskan Coastal Current flow emanating from the Chukchi shelf interacts with the typically westward flow on the Beaufort shelf to form a number of complex circulation features. These often include an anticyclonic eddy offshore of Cape Simpson where historical observations indicate that bowhead whales often feed. The eddy may aggregate zooplankton and thus enhance the feeding efficiency of bowheads in this region.