Origin and Fate of the Chukchi Slope Current Using a Numerical Model and In-Situ Data

A regional coupled sea ice-ocean model and mooring/shipboard measurements are used to investigate the origins, seasonality, and downstream fate of the Chukchi Slope Current (CSC). Three years (2013-2015) of model integration indicates that, in the mean, the model slope current transports similar to 0.45 Sv of Pacific water northwestward along the Chukchi continental slope. Only 62% of this water emanates from Barrow Canyon, while the rest (38%) is fed by a westward jet extending from the southern Beaufort Sea. The jet merges with the outflow from the canyon, forming the CSC. Due to these two distinct origins, the slope current in the model has a double velocity core at times. This is consistent with the double-core structure of the slope current seen in ship-based observations. Seasonal changes in the volume, heat, and freshwater transports by the slope current appear to be related to the changes in the upstream flows. A tracer diagnostic in the model suggests that the part of the slope current over the upper continental slope continues westward toward the East Siberian Sea, while the portion of the current overlying deeper isobaths flows northward into the Chukchi Borderland, where it ultimately gets entrained into the Beaufort Gyre. Our study provides a detailed and complete picture of the slope current.Plain Language Summary Water from the Pacific Ocean enters the Arctic domain through the Bering Strait, between the United States and Russia, and subsequently flows northward across the wide and shallow Chukchi Sea. The Pacific- origin water is a critical component of the regional ecosystem and helps set the hydrographic structure of the water column. Previous work suggests that, upon reaching the edge of the Chukchi shelf, much of the water is transported toward the west over the continental slope by the Chukchi Slope Current. However, the precise origin and fate of this current remain uncertain. Using a regional coupled sea ice-ocean model and mooring/shipboard data, we find that the slope current is fed by the outflow from Barrow Canyon in the northeast Chukchi Sea, and also by a westward jet extending from the southern Beaufort Sea. Although some portion of the water advected by the slope current remains on the upper continental slope, as the current overlying deeper isobaths flows northward, part of the water gets entrained into the Beaufort Gyre. These results improve our knowledge of the Pacific water pathways in the Arctic Ocean and would contribute to further understanding of the changing Arctic, such as sea ice loss.

Automated summary

The study explores the origins, seasonality, and downstream fate of the Chukchi Slope Current using a regional coupled sea ice-ocean model and mooring/shipboard data. It finds that the slope current has a double velocity core in the model, with water originating from both Barrow Canyon and a westward jet extending from the southern Beaufort Sea. This study provides a comprehensive understanding of the slope current in the Arctic region.