Preprints
https://doi.org/10.5194/tc-2020-240
https://doi.org/10.5194/tc-2020-240

  27 Aug 2020

27 Aug 2020

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

Modeling intensive ocean–cryosphere interactions in Lützow-Holm Bay, East Antarctica

Kazuya Kusahara1, Daisuke Hirano2,3, Masakazu Fujii4,5, Alexander D. Fraser6, and Takeshi Tamura4,5 Kazuya Kusahara et al.
  • 1Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Kanagawa, 236-0001, Japan
  • 2Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, 060-0819, Japan
  • 3Arctic Research Center, Hokkaido University, Sapporo, Hokkaido, 001-0021, Japan
  • 4National Institute of Polar Research, Tachikawa, Tokyo, 190-8518, Japan
  • 5Graduate University for Advanced Studies (SOKENDAI), Tachikawa, Tokyo, 190-8518, Japan
  • 6Australian Antarctic Program Partnership, University of Tasmania, Hobart, Tasmania, 7004, Australia

Abstract. Basal melting of Antarctic ice shelves accounts for more than half of the mass loss from the Antarctic Ice Sheet. Many studies have focused on active basal melting at ice shelves in the Amundsen-Bellingshausen Seas and the Totten Ice shelf, East Antarctica. In these regions, the intrusion of Circumpolar Deep Water (CDW) onto the continental shelf is a key component for the localized intensive basal melting. Both regions have a common oceanographic feature: southward deflection of the Antarctic Circumpolar Current on the eastern flank of ocean gyres brings CDW onto the continental shelves. The physical setting of Shirase Glacier Tongue (SGT) in Lützow-Holm Bay corresponds to a similar configuration for the Weddell Gyre in the Atlantic sector. Here, we conduct a 2–3 km resolution simulation of an ocean-sea ice-ice shelf model using a newly-compiled bottom topography dataset in the bay. The model can reproduce the observed CDW intrusion along the deep trough. The modeled SGT basal melting reaches a peak in summer and minimum in autumn and winter, consistent with the wind-driven seasonality of the CDW thickness in the bay. The model results suggest the existence of eastward-flowing undercurrent on the upper continental slope in summer, and the undercurrent contributes to the seasonal-to-interannual variability of the warm water intrusion into the bay. Furthermore, numerical experiments with and without fast-ice cover in the bay demonstrate that fast ice plays a role as an effective thermal insulator and reduces local sea-ice formation, resulting in much warmer water intrusion into the SGT cavity.

Kazuya Kusahara et al.

 
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Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Kazuya Kusahara et al.

Kazuya Kusahara et al.

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Short summary
We used an ocean-sea ice-ice shelf model with a 2–3 km horizontal resolution to investigate ocean-ice shelf/glacier interactions in Lützow-Holm Bay, East Antarctica. The numerical model reproduced the observed warm water intrusion along the deep trough in the bay. We examined in detail (1) water mass changes between the upper continental slope and shelf regions and (2) fast ice role on the ocean conditions and basal melting at Shirase Glacier Tongue.