日本地球惑星科学連合2022年大会

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[J] 口頭発表

セッション記号 A (大気水圏科学) » A-CC 雪氷学・寒冷環境

[A-CC29] アイスコアと古環境モデリング

2022年5月26日(木) 09:00 〜 10:30 301B (幕張メッセ国際会議場)

コンビーナ:川村 賢二(情報・システム研究機構 国立極地研究所)、コンビーナ:竹内 望(千葉大学)、阿部 彩子(東京大学大気海洋研究所)、コンビーナ:植村 立(名古屋大学 環境学研究科)、座長:川村 賢二(情報・システム研究機構 国立極地研究所)、竹内 望(千葉大学)

10:15 〜 10:30

[ACC29-06] A one-dimensional temperature and age modeling study for evaluation of sites for an oldest ice core around Dome Fuji, Antarctica

★Invited Papers

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

The recovery of a new Antarctic ice core to cover ~1.5 million years (Ma) before present will advance our understanding of the climate system dynamics during Quaternary. Recent glaciological field surveys have been conducted to select the location of the next deep drilling around Dome Fuji (DF), in particular, the spatial distribution of bedrock topography and internal layers of the ice have been acquired by ground-based radar surveys.
In this study, we use a one-dimensional ice flow model to investigate the age of ice, especially in the lowest few hundred meters and thermal conditions at ice-bed interfaces. We investigated the influence from ice thickness, accumulation rate, geothermal heat flux with typical ranges based on glaciological conditions near the DF region. The basal melting rate is diagnosed with a temperature gradient at the ice base. The model results were evaluated with observed age and temperature profiles from DF ice core and borehole temperature observations.
We find that the melting at the ice sheet base is maximum during glacial periods, because the basal temperature lags to the surface temperature. An excessive geothermal heat flux (~5 mW/m2) above the threshold of basal melting can eliminate the old ice, due to the melting during glacial periods. From sensitivity experiments to investigate respective roles of ice thickness and surface mass balance, in the range of typical values of near DF. The one-dimensional model is applied to the vicinity of DF along a 54-km long transect. The results indicate that the model tends to overestimate the age of ice compared to observational isochrones data, suggesting ice thickness is most crucial factor for consideration and evaluation of sites for drilling.