Thursday 25 August 2005

GP3
1330-1500 hours

378
Decoding sea ice thickness dynamics - Impact of ICESat, CryoSat, GRACE and in-situ data
Braun, Alexander¹, Shum, C K², Han, Shin-Chan², Csatho, Beata², Matsumoto, Koji³, ARCGICE Team⁴
1 University of Calgary, AB, Canada
2 The Ohio State University, OH, USA
3 National Astronomical Observatory of Japan
4 ESA project EOP-SM/1090
Author email: braun@ucalgary.ca
Recently launched satellite missions such as ICESat, GRACE, and in the near future CryoSat have revolutionized our capabilities of doing geodesy in the polar regions. At present, satellite altimetry provides dense elevation data over ice sheets and sea ice. Moreover, spatio-temporal changes can be analyzed in order to understand the dynamic processes in the polar regions. Sea ice parameters such as freeboard height and thickness are crucial for climate and ocean modeling due to their controlling effects on ocean-atmosphere heat flux and the transport of sea ice in the polar oceans. Recent satellite gravimetry integrates over all mass changes and significantly improved geoid models of the polar oceans. Combined, satellite geodetic observations enable the derivation of sea ice parameters which can be calibrated with in situ observations and historical data. Maps of sea ice freeboard height and its spatio-temporal changes will be presented and correlated with in situ data and remote sensing data of sea ice concentration/extent (SSMI, AMSR). The obvious caveats in our approach are our limited knowledge of dynamic ocean topography, ocean tides, and the geoid. Several models have been analyzed in order to find an optimal representation of sea ice freeboard height using altimetry data. Due to the different penetration depth of radar and laser signals, snow cover and sea ice thickness could be separated, once CryoSat becomes operational. In situ data and a suite of independent models are used to estimate the individual error contributions of geoid, tides, dynamic topography, and snow density/thickness on the sea ice thickness error budget. A strategic assessment of how multiple sensors can be linked to better understand the sea ice thickness dynamics on the polar oceans will conclude the presentation.

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