[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

*平野 大輔¹、田村 岳史¹、草原 和弥²、藤井 昌和¹、山崎 開平³、 中山 佳洋³、小野 数也³、板木 拓也⁴、青山 雄一¹、清水 大輔¹、溝端 浩平⁵、大島 慶一郎³、野木 義史¹、Rintoul Stephen^6,7,8、Wijk Esmee^6,8、Greenbaum Jamin⁹、Blankenship Donald¹⁰、青木 茂³ (1.国立極地研究所、2.海洋研究開発機構、3.北海道大学低温科学研究所、4.産業技術総合研究所、5.東京海洋大学、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)

キーワード：南大洋、南極氷床、東南極、トッテン氷河、氷床海洋相互作用

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.