Assessment of altimetry using ground-based GPS data from the 88S Traverse, Antarctica, in support of ICESat-2

We conducted a 750 km kinematic GPS surveys, referred to as the 88S Traverse, based out of South Pole Station, Antarctica between December 2017 and January 2018. The ground-based survey was designed for the validation of elevation data products from NASA's Ice, Cloud, and land Elevation Satellite 2 (ICESat-2), which launched in September 2018. The 88S Traverse intersects 20% of the ICESat-2 orbits on a route that has been flown by 2 different Operation IceBridge laser altimeters, including the Airborne Topographic Mapper (ATM) and the University of Alaska, Fairbanks (UAF) Lidar. Here we present the survey methods, an overview of the quality of the ground-based data, and an assessment of the airborne altimetry in this region. Results indicate that the GPS data are internally consistent (1.1 ± 4.1 cm). Further, based on comparisons with the GPS data, the surface elevation biases for ATM and the UAF Lidar ranged from -9.5 to 3.6 cm, while assessments of measurement precision are 14.1 cm or better. These values suggest that the ground-based and airborne elevation data are appropriate for the validation of ICESat-2 surface elevation data. GPS data from the 2017-2018 88S Traverse, the first of four planned surveys, were used to evaluate ICESat-2 elevation data during its commissioning phase; a second 88S Traverse is about to be conducted, and will be concurrent with ICESat-2 data collection.