The Physical Properties of the US ITASE Ice Cores

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9980434MeeseThis award is for support for a project to examine the visual stratigraphy, physical and structural properties of the U.S. ITASE ice cores spanning the last 200 years of snow accumulation in Antarctica. A first priority will be to examine visual stratigraphy to delineate annual layer structure for dating purposes and to determine to as great a depth as possible, accumulation variability over the full length of a stratigraphically dated core. A second objective is to measure and analyze depth-density profiles. The rate of snow and firn densification depends on both the rate at which the snow is deposited and the in situ snow temperature. These data can and will be used to derive average snow accumulation rates for the sites where annual layer structure is difficult to decipher or where stratigraphic analysis fails altogether. A third objective will entail measurements of mean crystal size over the full length of a core. Crystal growth is a strongly temperature dependent process and measurements to be made on ITASE cores will help to bridge a significant data gap that exists in the mean annual temperature range, -31 to -50 degrees centigrade. Additionally, crystal size data can also be used, in conjunction with ice loads based on density profile measurements, to extract mean accumulation rates for these sites where stratigraphic dating of cores proves difficult or impossible to accomplish. This is likely to occur at the lowest accumulation/lowest temperature sites along the ITASE traverse routes.