992 / 2024-09-20 00:20:04

Dynamics of Water Mass Exchange on the Central Ross Sea Slope near the Glomar Challenger Trough, Ross Sea

Cross-slope exchange,Momentum balance,Topographic Rossby Waves

Water mass exchange across the slope of the Ross Sea has a critical impact on not only the physical and biological processes of the Ross Sea shelf but also on the meridional overturning circulation. The Central Ross Sea Slope (CRSS) functions as a crucial region for the exchange of water masses. In this study, a high-resolution coupled ocean-ice shelf-sea ice model is employed to investigate the controlling mechanisms for the cross-slope water mass exchanges. The vertical structure of cross-slope exchange is characterized by onshore transport in the AASW (Antarctic Surface Water) and CDW (Circumpolar Deep Water) layers and offshore transport in the DSW (Dense Shelf Water) layer. Momentum balance analysis indicates that cross-slope transport exhibits high-frequency oscillation, with a periodicity of approximately 34 hours, associated with the Topographic Rossby Waves (TRWs), but its contribution to the net transport is small. The offshore transport of DSW is driven by the pressure gradient force associated with interfacial form stress at the CDW/DSW interface and the bottom Ekman transport associated with the bottom velocity of the Antarctic Slope Current (ASC). The southeastward sea surface height gradient, induced by the DSW displacing less dense water in the bottom layer, drives the onshore transport of CDW. This process is partially counteracted by the transport driven by the baroclinic pressure gradient force and the transport driven by the advection term resulting from the spatial distribution in the velocity of ASC.