Enhancement of Basal Melting by Submesoscale Eddies in Ice Shelf Cavities of the Amundsen Sea

Basal melt rates in ice shelf cavities depend on the inflow of relatively warm water into the cavities that propagate towards the grounding lines where there is enhanced melting. However, the lateral and vertical heat transport by currents inside cavities remains poorly understood. Here we explore the nature of the vertical heat transport in ice shelf cavities using high-resolution nested ocean simulations of the Amundsen Sea region, including Thwaites, Pine Island, Crosson, and Dotson ice shelves. We demonstrate that rough topographic features and strong variations in ocean temperatures and salinities in ice shelf cavities can lead to energetic submesoscale variability in the form of meandering boundary currents, eddies, and internal gravity waves. We show how submesoscale flows inside ice shelf cavities can intermittently advect warm water laterally and vertically towards the ice shelf base, thus significantly impacting basal melt rates. Using sensitivity experiments by turning basal melt on and off, we demonstrate that the basal melt provides a dominant source of potential energy to drive submesoscale variability inside cavities. Hence, the interaction between basal ice melt and submesoscale variability can constitute positive feedback. As such, the efficiency of ice shelf cavities in absorbing the heat from inflow water masses is tied to submesoscale variability. Our study implies that simulating basal melting in ice shelf cavities may require resolving submesoscale processes.