Investigation of Interannual Sea Ice Thickness Variability in the Southern Ocean

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0130537AckleyThe proposed work will develop a systematic climatology of in situ antarctic sea ice thickness from observations made since 1980. Sea ice thickness is by far the least well known property - horizontal properties such as areal extent and compactness can be observed from satellites - but thickness information is necessary to constrain large-scale climate models. The three-dimensional growth and decay of antarctic sea ice is an important feature of the global climate system as it directly modifies ocean-atmosphere interaction in the Southern Ocean. The four major large-scale sea ice properties that need to be monitored for variability and change are ice thickness, compactness (including extent), movement, and deformation. In large-scale climate models, the lack of sea ice thickness data for validation introduces a "free"parameter for arbitrary tuning and allows a wide range of results which cannot be checked. Hence it is difficult to ascertain which model physics are correct, leading to divergent viewpoints about the sensitivity of the various parameters. This project will (1) provide an antarctic climatology of in situ sea ice thickness (and secondarily compactness) using the recently recovered 11,000 sea ice property records from 42 voyages between 1980 and 2000; (2) through validation studies, expand the in situ sea ice climatology to include remote sensinginformation from U.S. National Ice Center ice charts from 1995 to 2000, and (3) contribute to the greater knowledge of air-ice-ocean interaction by determining the relationship between an antarctic sea ice climatology, climate variability, and climate trends.The work will serve the community at large by linking the sea ice climatology results into the public NIC web-site for the validation of numerical model outputs, to obtain error-bounded input for dataassimilation, to study sea ice processes, and for operational use.***