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The role of double-diffusive convection in basal melting of Antarctic ice shelves

Citation

Rosevear, MG and Gayen, B and Galton-Fenzi, BK, The role of double-diffusive convection in basal melting of Antarctic ice shelves, Proceedings of the National Academy of Sciences of the United States of America, 118, (6) Article e2007541118. ISSN 0027-8424 (2021) [Refereed Article]

Copyright Statement

Copyright ę 2022 the Author(s).

DOI: doi:10.1073/pnas.2007541118

Abstract

The Antarctic Ice Sheet loses about half its mass through ocean-driven melting of its fringing ice shelves. However, the ocean processes governing ice shelf melting are not well understood, contributing to uncertainty in projections of Antarctica's contribution to global sea level. We use high-resolution large-eddy simulation to examine ocean-driven melt, in a geophysical-scale model of the turbulent ice shelf-ocean boundary layer, focusing on the ocean conditions observed beneath the Ross Ice Shelf. We quantify the role of double-diffusive convection in determining ice shelf melt rates and oceanic mixed layer properties in relatively warm and low-velocity cavity environments. We demonstrate that double-diffusive convection is the first-order process controlling the melt rate and mixed layer evolution at these flow conditions, even more important than vertical shear due to a mean flow, and is responsible for the step-like temperature and salinity structure, or thermohaline staircase, observed beneath the ice. A robust feature of the multiday simulations is a growing saline diffusive sublayer that drives a time-dependent melt rate. This melt rate is lower than current ice-ocean parameterizations, which consider only shear-controlled turbulent melting, would predict. Our main finding is that double-diffusive convection is an important process beneath ice shelves, yet is currently neglected in ocean-climate models.

Item Details

Item Type:Refereed Article
Keywords:iceľocean interactions, double-diffusive convection, basal melting of Antarctic ice shelves, large-eddy simulation, thermohaline staircases
Research Division:Earth Sciences
Research Group:Physical geography and environmental geoscience
Research Field:Glaciology
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)
UTAS Author:Rosevear, MG (Miss Madelaine Rosevear)
UTAS Author:Galton-Fenzi, BK (Dr Ben Galton-Fenzi)
ID Code:150651
Year Published:2021
Web of Science® Times Cited:7
Deposited By:Australian Antarctic Program Partnership
Deposited On:2022-06-23
Last Modified:2022-07-21
Downloads:0

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