Observations of submesoscale eddy-driven heat transport at an ice shelf calving front

Abstract

Antarctica’s ice shelves buttress the continent’s terrestrial ice, helping slow the loss of grounded ice into the ocean and limiting sea level rise. Ice-ocean interaction plays a critical role in ice shelf stability by driving basal melt rates. Consequently, improved prediction of the future state of ice shelves lies in understanding the coastal ocean mechanics that deliver heat to their cavities. Here, we present autonomous glider-based observations of a coherent structure at the calving front of a cold-water cavity ice shelf (Nansen Ice Shelf, East Antarctica). This ~10 km-wide eddy dominated the local ocean circulation in the austral summer of 2018/2019, promoting an upwelling of cold ice shelf water and a deepening of warm surface water. Microstructure turbulence measurements show a resulting maximum vertical heat transport of 10 W m−2 at depths equivalent to the ice shelf draft. Similar eddy-driven heat transport further into the ice shelf cavity would support enhanced summertime melt in regions of shallower ice draft.