Continuation of Physical Properties of the Siple Dome Deep Ice Core

0087160

Alley

This award provides support to continue paleoclimate and ice dynamical studies of the Siple Dome deep ice core and associated shallow cores from West Antarctica, to help understand the history of climate and ice-sheet stability. Visible examination of the ice cores contributes to the required dating of the paleoclimatic records. Because ice-flow corrections for accumulation rates are difficult in deep ice, a new physically based paleoclimatic indicator of temperature or snow accumulation will be developed, based on bubble-size histories and on the physics of firn densification and grain growth. The paleoclimatic reconstruction of summer temperatures will be accomplished through observation and analysis of the rare melt layers in the ice core. Studies of the distribution of climate change in space and time will be continued, focusing on the possibility that a climate oscillation of ~ 1500 years has combined with 'noise' from changes in freshwater fluxes to force rapid, large, nearly synchronous, widespread to global changes in the mode of operation of the climate system. Visual and c-axis studies of ice grains in the core will help detect flow disturbances, such as the ones which were seen in the GISP2 ice cores, if they are present in the Siple Dome core. The results of this study should lead to a better understanding of rapid climate change in Antarctica and, through comparison, to other records worldwide. The study should also contribute to knowledge of the flow and stability of the West Antarctic ice sheet.