Poleward eddy-induced warm water transport across a shelf break off Totten Ice Shelf, East Antarctica

Daisuke Hirano,Hiroko Sasaki,Hiroto Murase,Shigeru Aoki,Kohei Mizobata,Takeshi Tamura

doi:10.1038/s43247-021-00217-4

Abstract

Ice mass loss in the Wilkes Land sector of East Antarctica and the Amundsen and Bellingshausen Sea sectors of West Antarctica has contributed to a rise in sea levels over several decades. The massive continental ice behind the Totten Ice Shelf, equivalent to a few meters of sea-level rise, is grounded well below sea level and therefore, potentially vulnerable to oceanic heat. Here, we present analyses of comprehensive hydrographic observations at the continental slope and shelf break regions off Totten Ice Shelf. We provide robust evidence that the relatively warm Circumpolar Deep Water that originates at intermediate depths in the Antarctic Circumpolar Current is transported efficiently towards the shelf break by multiple cyclonic eddies. We propose that these semi-permanent cyclonic circulations play a critical role in transporting the available ocean heat towards Totten Ice Shelf, and melting it from underneath, thus eventually influencing the global climate.

Highlights

Ice mass loss in the Wilkes Land sector of East Antarctica and the Amundsen and Bellingshausen Sea sectors of West Antarctica has contributed to a rise in sea levels over several decades
A recent study has demonstrated that the mass loss of the Antarctic Ice Sheet was in the Amundsen and the Bellingshausen Sea sectors of West Antarctica and in the Wilkes Land sector of East Antarctica[1]
Combined with the satellite-derived ocean circulation data, we demonstrated that quasi-stational cyclonic eddies found off the Sabrina Coast play a critical role in poleward Circumpolar Deep Water (CDW) transport, which is one of the presumable upstream determinants of the ocean heat flux into the TIS sub-ice cavity

Summary

Introduction

Ice mass loss in the Wilkes Land sector of East Antarctica and the Amundsen and Bellingshausen Sea sectors of West Antarctica has contributed to a rise in sea levels over several decades. We provide robust evidence that the relatively warm Circumpolar Deep Water that originates at intermediate depths in the Antarctic Circumpolar Current is transported efficiently towards the shelf break by multiple cyclonic eddies. We propose that these semi-permanent cyclonic circulations play a critical role in transporting the available ocean heat towards Totten Ice Shelf, and melting it from underneath, eventually influencing the global climate. Increased mass loss from the West Antarctic Ice. Sheet is principally driven by an increase in basal melting of the Amundsen and the Bellingshausen Sea ice shelves by the strengthening of warm CDW inflows[9,10]. CDW inflow across the shelf break is a crucial process controlling the mass balance for ice shelves/sheets and it eventually influences the Antarctic as well as global climate

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Results

Conclusion