[A-OS11] Ocean Mixing Frontiers

[AOS11-16] The role of double-diffusive convection in basal melting and mixed layer under Antarctic ice shelves

*Bishakhdatta Gayen^1,2, Madi Rosevear ^3,5, Ben Galton-Fenzi⁴ (1.The University of Melbourne, 2. Indian Institute of Science, 3.University of Tasmania , 4.Australian Antarctic Division, 5.University of Western Australia )

Keywords:Diffusive-convection, ocean interactions, large-eddy simulation, thermohaline staircases

The Antarctic Ice Sheet, which comprises the enormous ice volume on our planet, is losing mass at an alarming rate, contributing to a considerable global sea-level rise in the future. Ocean-driven melting is the largest cause of ice mass loss from the Antarctic continent. Therefore, accurate representation of ocean-driven melting is crucial for future sea-level predictions; however, the fine-scale ice shelf-ocean boundary layer (ISOBL) processes that control ocean melt rates are not well understood. Ocean-climate models cannot resolve the ISOBL and rely on parameterizations to predict melting. In this study, we use cutting-edge Large Eddy Simulation to examine the geostrophic boundary layer beneath an ice shelf for the first time. A small-scale mixing process (Diffusive Convection) is an emergent property of our simulations. It explains the water column structure and low melt rates observed beneath the Ross Ice Shelf under similar conditions. We show that Diffusive Convection is the primary control of basal melting and oceanic mixed layer formation and persists despite shear-generated turbulence. Thus, our finding has significant potential implications for ice-sheet models that rely on ocean melt rate parameterizations to predict ice sheet stability and evolution.