Spatial Characteristics and Dynamic Mechanisms of the Antarctic Slope Current in the Ross Sea

Coupled with the Antarctic Slope Front (ASF), the Antarctic Slope Current (ASC) mostly encircles Antarctica and has variable structures. Two regimes of the ASC/ASF have been identified in the Ross Sea, but the spatial characteristics of the ASC/ASF have not been depicted in detail, and the dynamical mechanisms of the two ASC/ASF regimes are still unclear. Using an eddy-permitting coupled regional ocean-sea ice-ice shelf model, we investigate the spatial characteristics and energetics of the ASC/ASF in the Ross Sea. Based on the simulated results, two distinct structures of the ASC/ASF have been identified in two regimes: (a) in Regime I, the westward ASC is characterized by a surface-intensified flow, predominantly driven by the barotropic pressure gradient; (b) in Regime II, the ASC is characterized by a bottom-intensified westward flow, dominated by the baroclinic pressure gradient, especially prominent where Dense Shelf Water (DSW) overflows. Furthermore, by conducting an energy budget analysis in the framework of the Lorenz Energy Cycle, we found that in Regime I the ASC is maintained by Ekman transport that piles up water against the slope and drives a conversion from Mean Kinetic Energy (MKE) to Mean Available Potential Energy (MAPE), whereas in Regime II the ASC is strengthened as a bottom-intensified current through DSW overflows, which release MAPE into MKE.

Details