Investigation of Tidal Aliasing and Climate Scale Processes in Sea Ice and Their Influence on Oceanic-Atmospheric Heat/Momentum Balances...

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9818645HansonThis proposed work is a study of how satellite data can be used to improve our understanding of the process by which the movement of the arctic and antarctic sea ice cover affects the exchange of heat and momentum between the atmosphere and the ocean. The key variable is differential motion of the sea ice: i.e. convergence, divergence, and shear, which produces areas of open water and significantly increases the atmosphere-ocean rates of exchange.The effort is concerned with short-period or high frequency variations in the differential motion, that are so rapid that they cannot be resolved by successive satellite passes. The bulk of satellite-derived ice motion data is on a three-day time scale with current capabilities extending down to one day. This is insufficient to resolve motions resulting from tides and inertial oscillations that have a period less than one day.This proposal uses an imaginative statistical approach to recover the amplitude of these oscillations from a data record whose sampling rate is once per day or lower. It is based on the premise that the power of tidal and inertial oscillations appears in the statistics of the data record, with the additional hypothesis that if the frequency of these oscillation is well-defined (as is the case for tides and inertial oscillations) then their effect is limited to a specific and predictable part of the observed data record. The approach will be tested by comparing observations from the Weddell Sea Ice Camp, where the power of tidal and inertial oscillation was measured directly, with synchronous satellite imagery, where the power of these oscillations will be recovered statistically.Potentially the techniques derived from this project will allow more accurate determinations of the structure of the antarctic atmosphere and oceans by introducing better and more realistic numerical approximations to sea ice formation and water mass modification processes that have global connections.