[M-IS03] The Southern Ocean and the Antarctic Ice Sheet dynamics in past, present and future

[MIS03-P05] On-Shelf Circulation of Warm Water Toward the Totten Ice Shelf, East Antarctica

*Daisuke Hirano¹, Takeshi Tamura¹, Kazuya Kusahara², Masakazu Fujii¹, Kaihe Yamazaki³, Yoshihiro Nakayama³, Kazuya Ono³, Takuya Itaki⁴, Yuichi Aoyama¹, Daisuke Simizu¹, Kohei Mizobata⁵, Kay I. Ohshima³, Yoshifumi Nogi¹, Stephen R. Rintoul^6,7,8, Esmee van Wijk^6,8, Jamin S. Greenbaum⁹, Donald D. Blankenship¹⁰, Shigeru Aoki³ (1.National Institute of Polar Research, 2.Japan Agency for Marine-Earth Science and Technology, 3.Institute of Low Temperature Science, Hokkaido University, 4.National Institute of Advanced Industrial Science and Technology, 5.Tokyo University of Marine Science and Technology, 6.CSIRO Oceans & Atmosphere, 7.Centre for Southern Hemisphere Oceans Research, 8.Australian Antarctic Program Partnership, 9.Scripps Institution of Oceanography, 10.Institute for Geophysics, The University of Texas)

Keywords:Southern Ocean, Antarctic Ice Sheet, East Antarctica, Totten Glacier, ice-ocean interaction

Mass loss from the Antarctic Ice Sheet directly results in global sea-level rise. The continental ice behind the Totten Ice Shelf (TIS) in East Antarctica appears vulnerable to ocean forcing and may result in >3.5-m rise in sea level. Thus, the behavior of warm water can control the dynamics of the TIS and Totten Glacier. We analyzed comprehensive in-situ observations over the unprecedentedly broad region from the continental slope to the TIS. Our multibeam sonar survey has provided detailed information on >1000-m-deep glacial troughs connecting the TIS cavity with an outer depression. Hydrographic observations revealed the on-shelf circulation of warm modified Circumpolar Deep Water toward the TIS through a deep topographic passage, which was also supported by numerical simulations. Mooring records and multi-year hydrographic profiles at the TIS front also demonstrated tidal to interannual temperature variability near the bottom. These results provide insight into the pathways and processes regulating heat transport to the TIS, information that is critical for understanding the response of the East Antarctic Ice Sheet to climate change.