CryoSat sea ice validation and process studies in the European Arctic

The project has focused on analysis of sea ice physics data from previous and new field expeditions in order to establish the relationship between freeboard, snow cover, snow & ice density and snow & ice thickness. This relationship is the basis for the ice thickness retrieval algorithm for CryoSat-2. This algorithm needs to be adjusted and validated for different regions and months of the year using available data from in situ field experiments and airborne campaigns. Historical data on ice and snow properties have been analysed to improve the regional and seasonal statistics of snow thickness, ice density and other key parameters needed to validate the altimeter retrievals. Field investigations have been conducted in the Svalbard region and the Fram Strait to obtain in situ measurements of ice thickness, freeboard, density and snow properties. Data from these investigations have been analysed and presented in the report.
Examples of airborne radar (ASIRAS) and laser data (ALS) from the previous CryoVex 2006 and 2008 campaigns have been analysed to study the return signals from different ice and snow surfaces. Radar and laser altimeter signals have different reflections from the surface. Laser altimeter signals are reflected from the snow surface, while radar altimeter signals are in principle reflected from the snow-ice interface (as long as the snow is dry). Both radar and laser altimeter data can be used to measure freeboard and convert freeboard to thickness. By combining high-resolution altimeter profiles with scanning laser data and SAR images, it is possible to separate leads with open water or thin ice from thick ice floes with ridges. Examples of waveform data from ASIRAS covering different ice types have been presented. Satellite laser altimeter data from IceSat have been obtained for selected periods from 2003 to 2008 and analyzed for the Fram Strait area, where surface roughness and ice freeboard and thickness have been retrieved. The first examples of CyoSat level 1b data have been obtained over sea ice in the Fram Strait, but results are not yet available. Results of the project have been published in journals and presented at conferences and workshops. Finally, plans for participation in the CryoSat post-launch calval experiment in 2011 (CryoVex 2011) have been prepared.