[M-IS15] Global Antarctic Science: connecting the chain of changing huge ice sheets and global environments

[MIS15-07] Direct observations of ocean heat transport toward the Totten Ice Shelf in East Antarctica

*Yoshihiko Ohashi¹, Daisuke Hirano^1,2, Kohei Mizobata³, Kazuya Kusahara⁴, Kazuki Nakata⁵, Kazuya Ono⁶, Masakazu Fujii^1,2, Ryosuke Makabe^1,2, Kay I. Ohshima⁶, Takeshi Tamura^1,2, Shigeru Aoki⁶ (1.National Institute of Polar Research, 2.SOKENDAI, 3.Tokyo University of Marine Science and Technology, 4.Japan Agency for Marine-Earth Science and Technology, 5.Japan Aerospace Exploration Agency, 6.Hokkaido University)

Keywords:Ocean heat transport, Totten Ice Shelf, East Antarctica, Direct observation

The Totten Glacier, the largest contributor to global sea-level rise from East Antarctica, is susceptible to ocean forcing. Here, we used a 2-year mooring time-series record and repeated hydrographic profiles from the deep trough, the main pathway of offshore-originating warm modified Circumpolar Deep Water (mCDW) toward the Totten Ice Shelf, to examine the temporal variabilities in the properties of the mCDW and resulting ocean heat transport. Along-trough mCDW inflows were bottom-intensified and occurred throughout the year in the southern branch of the deep trough. The ocean heat transport by mCDW inflow was estimated to be 0.39 ± 0.12 TW, accounting for 50–60% of the heat required for basal melt. The properties of mCDW inflows exhibited notable interannual and seasonal variations, marked by decreasing temperatures and increasing dissolved oxygen levels during winter and spring. These variations are influenced by the variability in sea ice production over the upstream Dalton Polynya. The intermittent local coastal processes could determine mCDW modification and ocean forcing on the Totten Glacier and its potential influence on global sea levels.