[A-CC29] アイスコアと古環境モデリング

[ACC29-05] 過去30年以上の地上氷床レーダ探査による南極ドームふじ周辺の高解像基盤地形

*津滝 俊¹、藤田 秀二^1,2、川村 賢二^1,2,3、阿部 彩子^1,4、福井 幸太郎⁵、本山 秀明^1,2、保科 優⁶、中澤 文男^1,2、小長谷 貴志⁴、大野 浩⁷、大藪 幾美¹、齋藤 冬樹³、杉浦 幸之助⁸、鈴木 利孝⁹ (1.国立極地研究所、2.総合研究大学院大学、3.海洋研究開発機構、4.東京大学、5.立山カルデラ砂防博物館、6.名古屋大学、7.北見工業大学、8.富山大学、9.山形大学)

キーワード：南極氷床、アイスレーダ、基盤地形

The retrieval of continuous ice core records of more than 1 Myr is an important challenge in palaeo-climatology. For identifying suitable sites for drilling such ice, the knowledge of the subglacial topography and englacial layering is crucial. For this purpose, extensive ground-based ice radar surveys have been conducted around Dome Fuji in the East Antarctic plateau during the 2017–2018, 2018–2019 and 2021–2022 austral summers by the Japanese Antarctic Research Expedition, on the basis of ground-based radar surveys over the previous ~30 years. High-gain Yagi antennae were used to improve the antenna beam directivity and thus attain a significant decrease in hyperbolic features in the echoes from mountainous ice-bedrock interfaces. We combined the new ice thickness data with the previous ground-based data since the 1980s to generate an accurate high-spatial resolution (up to 0.25 km between survey lines) ice thickness map. The new map reveals a complex landscape composed of networks of subglacial valleys and highlands. In addition, our map is compared with a few bedrock topography maps compiled by earlier independent efforts based on airborne radar data, to examine the difference in features between the datasets. We also examined geographical and glaciological parameters such as bed roughness, bed slope, driving stress and hydraulic head based on new ice thickness and bed elevation data. These results provide crucial knowledge for decisions of the location for the new drilling.