Satellite radar altimetry over sea ice - from Seasat to CryoSat
University College London,
London WC1E 6BT,
Sea ice represents one of key uncertainties in the future temperature rise predicted by Global Climate Models (GCM's). However GCM's simulations of future changes sea ice, in particular in ice thickness, vary widely. Satellite altimeters have the potential to provide unique data related to key climatic properties of sea ice related to the extent, thickness and roughness of ice floes.
In this paper we review over two decades of progress in satellite altimetry over sea ice from Seasat though to CryoSat. Early results from Seasat and Geosat demonstrated that the extraction of marine geoid information and sea ice thickness might one day be possible using space-borne altimetry. It was the ERS missions, however, which provided the first altimetric coverage of the high Arctic that allowed the first views of the polar ocean floor and of a highly dynamic sea ice cover to be revealed.
Recent news stories have talked widely of the dramatic retreat of summer sea ice extent during the first years of the 21st century. We will show the most recent results from Envisat and CryoSat with which we hope to answer the question as to whether Arctic sea ice has also undergone an equally dramatic thinning.