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Abstract. The Chukchi Slope Current is a westward-flowing currentalong the Chukchi slope, which carries Pacific-origin water from the Chukchishelf into the Canada Basin and helps set the regional hydrographicstructure and ecosystem. Using a set of experiments with an idealizedprimitive equation numerical model, we investigate the energetics of theslope current during the ice-covered period. Numerical calculations showthat the growth of surface eddies is suppressed by the ice friction, whileperturbations at mid-depths can grow into eddies, consistent with linearinstability analysis. However, because the ice stress is spatially variable,it is able to drive Ekman pumping to decrease the available potential energy(APE) and kinetic energy of both the mean flow and mesoscale eddies over avertical scale of 100 m, well outside the frictional Ekman layer. The rateat which the APE changes is determined by the vertical density flux, whichis negative as the ice-induced Ekman pumping advects lighter (denser) waterupward (downward). A scaling analysis shows that Ekman pumping will dominatethe release of APE for large-scale flows, but the effect of baroclinicinstability is also important when the horizontal scale of the mean flow isthe baroclinic deformation radius and the eddy velocity is comparable to themean flow velocity. Our numerical results highlight the importance of icefriction in the energetics of the slope current and eddies, and this may berelevant to other ice-covered regions. 

Abstract A simplified quasigeostrophic (QG) analytical model together with an idealized numerical model are used to study the effect of uneven ice–ocean stress on the temporal evolution of the geostrophic current under sea ice. The tendency of the geostrophic velocity in the QG model is given as a function of the lateral gradient of vertical velocity and is further related to the ice–ocean stress with consideration of a surface boundary layer. Combining the analytical and numerical solutions, we demonstrate that the uneven stress between the ice and an initially surface-intensified, laterally sheared geostrophic current can drive an overturning circulation to trigger the displacement of isopycnals and modify the vertical structure of the geostrophic velocity. When the near-surface isopycnals become tilted in the opposite direction to the deeper ones, a subsurface velocity core is generated (via geostrophic setup). This mechanism should help understand the formation of subsurface currents in the edge of Chukchi and Beaufort Seas seen in observations. Furthermore, our solutions reveal a reversed flow extending from the bottom to the middepth, suggesting that the ice-induced overturning circulation potentially influences the currents in the deep layers of the Arctic Ocean, such as the Atlantic Water boundary current. 

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 ∼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.