The Circulation of the Deep Bering Sea and Exchanges with the North Pacific: A High-Resolution Model Perspective

The general circulation of the deep Bering Sea determines volume and property transport onto the shelf and further north into the Arctic Ocean. It is usually described as a cyclonic gyre, with mesoscale features of importance to the overall circulation scheme. Some of these features are identified and examined in more detail using results from two high-resolution (1/12-deg or 9-km and 1/48-deg or 2.3-km) pan-Arctic ocean simulations. A number of eddies, both anticyclonic and cyclonic, are identified in the 9-km model results. Typical diameters of these eddies are 120 km and greater, velocities are up to 40 cm/s and lifetimes are typically a few months. These modeled eddy statistics compare reasonably well with satellite-tracked buoy observations. However, the 9-km grid size is only eddy-permitting, as it can minimally resolve eddies with diameters as small as 36 km but not smaller features. To address this issue, results from an eddy-resolving model with the grid size of 2.3-km are included for comparison. A significant improvement is demonstrated in the representation of eddies and their characteristics at increased spatial resolution. The role of mesoscale eddies observed and simulated along the Bering shelf break in shelf-basin exchange will be addressed.

Changes in the volume and property fluxes through Aleutian Island passes have the potential to affect the physical and biological dynamics within the Bering Sea. Since many of these passes are quite narrow and/or shallow, their representation requires high spatial resolution, which has been challenging for global ocean circulation models. For this reason and for completeness, the effects of variable inflow through the Aleutian passes on the Bering Sea circulation are also examined. Volume, heat and freshwater fluxes through the passes are calculated from model results and compared between the two model configurations and with observations, where available.