21 Aug 2023
 | 21 Aug 2023
Status: this preprint is currently under review for the journal TC.

Modeling seasonal-to-decadal ocean-cryosphere interactions along the Sabrina Coast, East Antarctica

Kazuya Kusahara, Daisuke Hirano, Masakazu Fujii, Alexander Fraser, Takeshi Tamura, Kohei Mizobata, Guy Williams, and Shigeru Aoki

Abstract. The Totten Ice Shelf (TIS) and Moscow University Ice Shelf (MUIS), along the Sabrina Coast of Wilkes Land, are the floating seaward terminuses of the second-largest freshwater reservoir in the East Antarctic Ice Sheet. Being a marine ice sheet, it is vulnerable to the surrounding ocean conditions. Recent comprehensive oceanographic observations, including bathymetric measurements off the Sabrina Coast, have shed light on the widespread intrusion of warm modified Circumpolar Deep Water (mCDW) onto the continental shelf and the intense ice-ocean interaction beneath the TIS. However, the spatiotemporal coverage of the observation is very limited. Here, we use an ocean–sea ice–ice shelf model with updated bathymetry to better understand the regional ocean circulations and ocean-cryosphere interactions. The model successfully captured the widespread intrusions of mCDW, local sea-ice production and the ocean heat and volume transports into the TIS cavity, facilitating an examination of the overturning ocean circulation within the cavities and the resultant ice-shelf basal melting. We found notable differences in the temporal variability of ice-shelf basal melting across the two adjacent ice shelves of the TIS and the western part of the MUIS. Ocean heat transport by mCDW controls the low-frequency interannual-to-decadal variability in ice-ocean interactions, but the sea-ice production in the Dalton Polynya strongly modifies the signals, explaining the regional difference between the two ice shelves. The formation of a summertime eastward-flowing undercurrent beneath the westward-flowing Antarctic Slope Current is found to play an important role in the seasonal delivery of ocean heat to the continental shelf.

Kazuya Kusahara et al.

Status: open (until 14 Oct 2023)

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  • RC1: 'Comment on tc-2023-78', Chengyan Liu, 06 Sep 2023 reply

Kazuya Kusahara et al.

Kazuya Kusahara et al.


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Short summary
This study focuses on the Totten and Moscow University Ice Shelves, East Antarctica. We used an ocean-sea ice-ice shelf model to better understand the regional interactions among ocean, sea ice, and ice shelf. We found that a combination of warm ocean water and local sea-ice production influences the regional ice-shelf basal melting. Furthermore, the model reproduced summertime undercurrent on the upper continental slope, regulating ocean heat transport onto the continental shelf.