[A-CC38] アイスコアと古環境モデリング

[ACC38-07] 氷床レーダ探査による東南極ドームふじ近傍の基盤地形

★招待講演

*津滝 俊¹、藤田 秀二^1,2、川村 賢二^1,2,3、Gogineni Prasad⁴、阿部 彩子^5,1、Braaten David⁶、Gallet Jean-Charles⁷、Isaksson Elisabeth⁷、Liefferinge Brice⁷、松岡 健一⁷、O’Neil Charles⁴、Paden John⁶、Rodriguez-Morales Fernando⁶、Taylor Ryan⁴、Yan Jie-Bang⁴、東 久美子^1,2、Greve Ralf⁸、Hudson Stephen⁷、Kohler Jack⁷、Kolpuke Shriniwas⁴、Li Linfeng⁴、Moholdt Geir⁷、本山 秀明^1,2、小長谷 貴志⁵、齋藤 冬樹³、福井 幸太郎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.アラバマ大学、5.東京大学、6.カンザス大学、7.ノルウェー極地研究所、8.北海道大学、9.富山県立山カルデラ砂防博物館)

キーワード：南極、基盤地形、氷床

Knowledge gained from ice core studies is crucial to understand the past and present climate and to predict the impacts of future climate changes. The International Partnership for Ice Core Sciences (IPICS) identified that drilling deep ice cores extending back in time to 1.5 million years (Ma) is crucial to better understand the change of the periodicity of the glacial cycles from 40 thousand years (ka) to the current 100 ka during the mid-Pleistocene transition (0.9−1.2 Ma). However, continuous ice core records extending beyond 1 Ma have not been retrieved from the Antarctic ice sheet. The Dome Fuji area in East Antarctica is one of the candidate areas where we may be able to find very old ice near the bottom of the ice sheet. The Japanese Antarctic Research Expedition (JARE) has conducted deep ice corings at Dome Fuji twice in the past decades. They recovered ice cores covering ages up to about 720 ka BP. Sufficient knowledge of the basal topography is crucial to find suitable candidates based on numerical ice sheet experiments. The JARE have accumulated radar sounding data in this area since 1984 (JARE 26). In order to reveal the more detailed basal topography to find candidate site of very old ice in the Dome Fuji area, a ground-based radar survey was conducted over an area of 20,000 km² with a line spacing of 5 km during JARE 59 (2017−2018 Antarctic summer). Based on results of these surveys, we conducted a more detailed radar survey at Dome Fuji in the 2018−2019 season as a collaboration between The University of Alabama, The University of Kansas, National Institute of Polar Research under Research Organization of Information and Systems (Japan), Norwegian Polar Institute and The University of Tokyo. we used two different radar systems for the data collection. A wideband VHF radar ice sounder developed by CReSIS, University of Kansas, and a conventional pulse-modulated VHF radar with high gain antennas from JARE. An ultrawideband microwave radar developed by the University of Alabama was used to survey shallow part of internal layers to investigate surface mass balance in the area. We investigated a distance of 2,700 km in an area of about 1,000 km². The final spacing between the survey lines varied between 0.5 km and 0.25 km. We analyze the JARE and CReSIS radar data to construct an improved map of the basal topography in the Dome Fuji area to foster the identification of a suitable drilling site in the region.