Campaign activities in ESA related to new and planned missions for improved analysis of the cryosphere

In the context of ESA's Living Planet Programme Cryosat and GOCE are under construction as first opportunity and core mission. Related to these missions several campaign activities are carried out and planned to increase knowledge about the observational system, to be able to compare and integrate with data from other observational techniques and to provide data for validation. Three campaigns are considered in this context of which two were carried out in 2002. ESAG, the first, collected airborne gravity and laser altimeter and scanning data of (sea-)ice surfaces in the Arctic. The second one LaRA, jointly funded by ESA and NASA, carried an airborne laser and radar system for ice profiling. A new campaign CRYOVEX is the first dedicated CryoSat validation campaign. It is planned for April 2003. The observational set up comprises an airplane carrying a laser and radar system for altimetry over ice and a helicopter with an EM bird for ice thickness measurements housed on the icebreaker-Polarstern. Analysis of data from these campaigns has the potential to improve the understanding of how laser and radar altimeters reflect on various snow and ice surfaces. Where laser tends to reflect on the snow, radar tends to penetrate through the snow layer onto the ice. This is of great importance when combining results from satellite missions carrying radar altimeters like Cryosat and laser altimeters like NASA’s Icesat. In determining sea-ice thickness a correction for snow cover is needed, either from models but preferably from the combination of laser and radar altimeter data. In estimating the sea-ice thickness a reference sea surface is needed. This could. be obtained from airborne gravimetry. This is being tried with airborne campaign data and verified using ice drills, and recorded ice thickness onboard icebreakers. The EM bird data will be used for this purpose in the CRYOVEX campaign. The potential and the shortcomings of the techniques are presented based on the analysis of the campaign data.