[M-IS08] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS08-P13] Modeling ocean-cryosphere interactions along the Sabrina Coast

*Kazuya Kusahara¹, Daisuke Hirano², Masakazu Fujii², Alexander D. Fraser³, Takeshi Tamura², Kohei Mizobata⁴, Guy D. Williams⁵, Shigeru Aoki⁶ (1.Japan Agency for Marine-Earth Science and Technology, 2.National Institute of Polar Research, 3. University of Tasmania, 4.Tokyo University of Marine Science and Technology, 5.First Institute of Oceanography, Qingdao, 6.Hokkaido University)

Keywords:Antarctic and Southern Ocean climate, ice-ocean interaction, ocean-sea ice-ice shelf modeling

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 Sheets. This glacier/ice-sheet system is a marine-ice-based ice sheet, thus being very vulnerable to the surrounding ocean conditions. Recent comprehensive oceanographic observations, including bathymetric measurements off the Sabrina Coast, shed light on intensive ice-ocean interaction between widespread intrusion of warm modified Circumpolar Deep Water (mCDW) onto the continental shelf and toward the TIS cavity, although spatiotemporal coverage of the observations is very limited. Here, we use an ocean–sea ice–ice shelf model with the recently updated bathymetry to better understand the overall ocean circulations from the shelf break to the TIS cavity and the regional ice-ocean interaction. The model reasonably captured the widespread mCDW intrusion, local sea-ice production, ocean heat and volume transports into the TIS cavity, overturning ocean circulations in the cavities, and the subsequent ice-shelf basal melting. We found notable differences in the temporal variability in ice-shelf basal melting at the two adjacent ice shelves of the TIS and the western part of MUIS (wMUIS). Ocean heat transport by mCDW controls low-frequency variability in ice-ocean interaction along the Sabrina Coast, but the sea-ice production in the Dalton polynya strongly modifies the signals and explains the regional difference between the two. The formation of a summertime eastward-flowing undercurrent beneath the westward-flowing Antarctic slope current is found to play a role in the seasonal ocean heat delivery to the continental shelf.