[M-IS15] グローバル南極学

[MIS15-07] 東南極トッテン棚氷下への海洋熱輸送の直接観測

*大橋 良彦¹、平野 大輔^1,2、溝端 浩平³、草原 和弥⁴、中田 和輝⁵、小野 数也⁶、藤井 昌和^1,2、真壁 竜介^1,2、大島 慶一郎⁶、田村 岳史^1,2、青木 茂⁶ (1.国立極地研究所、2.総合研究大学院大学、3.東京海洋大学、4.海洋研究開発機構、5.宇宙航空研究開発機構、6.北海道大学)

キーワード：海洋熱輸送、トッテン棚氷、東南極、直接観測

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.