Validation of CryoSat-2 products over the East Antarctica Ice Sheet

A main goal of the CryoSat-2 mission is to observe the variations in the elevation of the polar ice sheets within a few centimeters accuracy. To fulfill this challenging objective the CryoSat-2 Level 2 products need to be validated against independent measurements. Kinematic GNSS is a well established method to derive ground based surface elevation profiles with high accuracy, thus providing independent data to investigate the reliability of the radar altimetry observations. During the last decade a variety of such measurements could be realized in cooperation with the Russian Antarctic Expedition (RAE). Since 2007 we have realized the installation of several geodetic GNSS equipments on vehicles of the scientific and logistic convoys. These profiles between the Russian Antarctic research station Vostok (78° 28' S, 106° 50' E) and the coastal stations Mirny and Progress have a length of about 1,600 km each. Over several years the repetition of these profiles show that the elevation change is negligibly small in this region which forms an important precondition when comparing older GNSS profiles with recent CryoSat-2 data. Thus, the GNSS profiles give us the unique opportunity to validate both CryoSat-2 LRM-Mode data in the flat interior of the Antarctic Ice Sheet and SARIn-Mode data in the steep and rough coastal area. Validation results of the crossover analysis with Baseline B data are presented. We show how the new Baseline C processor version improves the observation quality. Furthermore, the alternate AWI processing version is used for comparison. Additionally, we will test the performance of the advanced swath processing technique in areas covered by the SARIn mode. Besides the Level 2 products we furthermore present the results of the validation of different digital elevation models (DEM). The probably most popular DEM for Antarctica, Bedmap2, is based mainly on ICESat, ERS-1 and small-scale local datasets. We show that a DEM based on CryoSat-2 data only has the advantage of a much higher consistency and of less interpolation errors due to the dense satellite ground tracks.