CryoSat-2 validation in East Antarctica: ASIRAS, ALS and in situ data analysis over Law Dome and Totten Glacier

The joint TOT-Cal / CryoVExANT2011 project contributes to the validation of the CryoSat-2 altimetry mission through investigations of a key portion of the East Antarctic ice sheet near Australia's Casey Station. Spanning parts of Law Dome and the Totten Glacier, the study site includes a diverse range of along and across track surface slopes (ranging from 0° to over 2°), significant spatial variability in accumulation rate, as well as significant regions with known surface lowering (at rates greater than 1 m/yr). These characteristics combine to provide valuable validation targets for the CryoSat-2 mission. Two field campaigns at the study site have been completed during the 2010/11 and 2011/12 austral summer field seasons. In 2010/11, the primary in situ data collected included skidoo based kinematic GPS transects and airborne nadir pointing laser observations of the surface elevation (from ICECAP flights of Operation ICEBridge). In 2011/12, the AWI Polar-6 aircraft successfully completed aerial surveys across the region equipped with the scanning LiDAR and the ESA Airborne SAR / Interferometric Altimeter System (ASIRAS). These datasets combine with in-situ GPS observations (fixed stations and skidoo-based kinematic sampling), corner cube reflector placements and snow pit surveys. Together, these data provide a number of near contemporaneous observations of surface elevation and firn characteristics along CryoSat-2 ground tracks. Through repeated airborne observation, an insight into temporal changes over the most dynamic parts of the Totten Glacier where focused surface lowering and mass loss is known to be occurring can be achieved. In this contribution, we present early results investigating spatial variability present in the 2011/12 ASIRAS data, as well as temporal changes observed between successive acquisitions of airborne laser data (2010/11 and 2011/12). Comparison with CryoSat-2 SAR-In data is also presented.