[M-IS08] 南大洋・南極氷床が駆動する全球気候変動

[MIS08-06] A one-dimensional temperature and age modeling study for selecting the drill site of the oldest ice core near Dome Fuji, Antarctica

*小長谷 貴志¹、阿部 彩子^1,2、齋藤 冬樹³、津滝 俊^2,4、藤田 秀二^2,4、川村 賢二^2,3,4、本山 秀明^2,4 (1.東京大学大気海洋研究所、2.国立極地研究所、3.海洋研究開発機構、4.総合研究大学院大学)

The recovery of a new Antarctic ice core spanning the last ~1.5 million years will advance our understanding of climate system dynamics during the Quaternary. Recent glaciological field surveys have been conducted to select the most suitable core location near Dome Fuji (DF), Antarctica. Specifically, ground-based radar-echo soundings have been used to acquire highly detailed images of bedrock topography and internal ice layers. In this study, we use a one-dimensional (1-D) ice flow model to compute the temporal evolutions of age and temperature, in which the ice flow is linked with not only transient climate forcing associated with past glacial?interglacial cycles, but also transient basal melting diagnosed along the evolving temperature profile. We investigated the influence of ice thickness, accumulation rate, and geothermal heat flux on the age and temperature profiles. The model was constrained by the observed temperature and age profiles reconstructed from DF ice?core analysis. The results of sensitivity experiments indicate that ice thickness is the most crucial parameter influencing the computed age of the ice because it is critical to the history of basal temperature and basal melting, which can eliminate old ice. The 1-D model was applied to a 54 km long transect in the vicinity of DF and compared with radargram data. We found that the basal age of the ice is mostly controlled by the local ice thickness, demonstrating the importance of high spatial resolution surveys of bedrock topography for selecting ice-core drilling sites.