[M-IS08] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

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

*Takashi Obase¹, Ayako Abe-Ouchi^1,2, Fuyuki SAITO³, Shun Tsutaki^2,4, Shuji Fujita^2,4, Kenji Kawamura^2,3,4, Hideaki motoyama^2,4 (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.National Institute of Polar Research, Research Organization of Information and Systems, 3.Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 4.The Graduate University for Advanced Studies, SOKENDAI)

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.