A first comparison of CryoSat-2 and ICEBridge altimetry from April 20, 2010 over Arctic Sea Ice

It is widely known that climate-driven loss of Arctic sea ice has occurred in the past decade. And in just the past few years a synoptic view of significant ice thickness changes (dominated by thinning and volume loss) across the Arctic Ocean has been provided by various investigations using ICESat and Envisat altimetry. Continued Arctic-wide observation of this (presumably secular) thinning, or other thickness changes, will be provided for the next 3 to 5 years by the Synthetic Aperture Interferometric Radar Altimeter (SIRAL) onboard CryoSat-2 as well as the suite of airborne instruments used by NASA's Operation IceBridge. On April 20 - just 12 days after the CryoSat-2 launch - during the IceBridge Spring 2010 campaign and in coordination with ESA, the NASA DC-8 flew precisely along some 670 km of a CryoSat-2 ground-track in the northernmost Arctic Ocean. The DC-8 collected scanning laser Airborne Topographic Mapper (ATM) data as well as a number of other measurements including digital imagery, lidar and radar altimetry which are virtually coincident and nearly simultaneous with SAR-mode SIRAL data collected by CryoSat-2. We will present initial comparative analyses of these CryoSat-2 data and the coincident airborne ATM data along with other IceBridge data including digital imagery. We will identify leads and floes in both the CryoSat and ATM data. Discrimination between leads, floes, and ridges as well as identification of recently refrozen leads in the CryoSat SIRAL data is the first step towards precise estimates of sea ice freeboard.