High Precision Borehole Temperature Measurements at Siple Dome, Antarctica, for Paleoclimate Reconstruction and Ice Dynamics Studies

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9726078 Waddington This award supports a project to obtain a number of high- precision borehole temperature profiles at Siple Dome for paleoclimate reconstruction and ice dynamics studies. Continuous temperature logs will be obtained in the 1 km deep fluid-filled Siple Dome borehole and in several 160 m deep holes along a 20 km north-south transect across Siple Dome. The borehole temperature data will be used to: a) establish the conductive heat flux across the basal interface of the ice sheet, b) reconstruct the surface temperature history at Siple Dome using geophysical inverse methods ("borehole paleothermometry"), c) constrain how thick the ice sheet was during the late Wisconsin, the magnitude of the Wisconsin/Holocene deglacial warming, and the background geothermal heat flux, d) determine the calibration constants for the oxygen-isotope paleothermometer at Siple Dome in the past, and e) establish the spatial variability of surface temperature on the 20 km scale near the main drill site during the last 100 years. The results at Siple Dome are expected to provide data needed to assess the short-term stability of the West Antarctic Ice Sheet, improve our understanding of the magnitude of past temperature changes at this southern hemisphere site, and lead to improved estimates of the pore close-off ages in the past which should lead to an improved age scale for the Siple Dome ice core.