UCLA

The Antarctic Slope Current (ASC) is a narrow and westward circulation feature that surrounds the Antarctic continental shelves. It regulates onshore ocean heat transport toward the Antarctic ice shelves and dense water outflow, playing an important role in global meridional overturning circulation, glacier melt, and sea level rise. Despite its significance to Earth's climate system, the circulation and heat transport around the Antarctic margins remain poorly understood due to the difficulties and expense in observation and modeling.

In this work, the dynamics of the ASC and the ice-ocean interactions around the Antarctic margins are investigated using high-resolution process-oriented simulations. The key results are summarized as follows: (i) Due to topographic eddy suppression, almost no wind-input momentum is transferred vertically over the continental slope; as a result, sea ice horizontally redistributes the wind-input momentum away from the continental slope, playing a critical role in the momentum balance of the ASC. (ii) Melt-induced freshening of the coastal waters that are buoyant compared with the open ocean leads to increased eddy-driven shoreward heat flux, which implies a positive feedback in a warming climate that may cause further melt of ice shelves. (iii) The West Antarctic slope undercurrent originates from the cyclonic vorticity input by meltwater upwelling in the cavities of West Antarctic ice shelves, which drives warm Circumpolar Deep Water toward the glaciers; increased basal melt therefore strengthens the slope undercurrent and enhances onshore heat transport, which indicates another positive feedback that may accelerate future melt, potentially further destabilizing the West Antarctic Ice Sheet.

The work in this dissertation advances the understanding of the ice-ocean system near the Antarctic margins and highlights previously unrecognized climate feedbacks that may be key to projecting future changes in Antarctic ice sheets and thus sea level rise. In addition, our results help guide future climate model development and future observations of near-Antarctic ocean heat flux and glacier melt.