The heat budget of the west Antarctic Peninsula Continental Shelf

The west Antarctic Peninsula (wAP) shelf has been one of the most rapidly-warming systems in the southern hemisphere, and glaciers terminating in this coast have undergone dramatic retreat. Oceanic processes leading to the observed warming of the shelf are of critical importance to explain this ice loss. Here, we examine the mechanisms of cross-shore and along-shore heat transport and their impact on the wAP heat budget using the output of a high-resolution numerical model as well as available hydrographic data. The model (ROMS) configuration is eddy-resolving at 1.5 km horizontal resolution, includes 24 vertical levels, and was forced with realistic meteorological fields and observed sea-ice (at the model boundaries) for two years. While previous studies have emphasized the transport of heat across the shelf break by small-scale baroclinic eddies, an eddy kinetic energy budget of the shelf also shows extensive energy conversion from mean to eddy flows by barotropic instability. Consistent with observations, large submarine troughs are the main pathway for the resulting eddy heat transport. While hotspots of eddy generation do exist near the shelf break, the model reveals that mean-to-eddy energy conversion continues to be significant as large warm water intrusions flow in the troughs across the shelf, highlighting the importance of eddy generation processes on the shelf. The fate of the heat supplied by these eddies to the shelf, and the implication for the retreat of glaciers is discussed.