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

Kelly M Brunt,Christopher F Larsen,Thomas A Neumann

doi:10.5194/tc-13-579-2019

Abstract

Abstract. We conducted a 750 km kinematic GPS survey, referred to as the 88S Traverse, based out of South Pole Station, Antarctica, between December 2017 and January 2018. This ground-based survey was designed to validate spaceborne altimetry and airborne altimetry developed at NASA. The 88S Traverse intersects 20 % of the ICESat-2 satellite orbits on a route that has been flown by two different Operation IceBridge airborne laser altimeters: the Airborne Topographic Mapper (ATM; 26 October 2014) and the University of Alaska Fairbanks (UAF) Lidar (30 November and 3 December 2017). Here we present an overview of the ground-based GPS data quality and a quantitative assessment of the airborne laser altimetry over a flat section of the ice sheet interior. Results indicate that the GPS data are internally consistent (1.1±4.1 cm). Relative to the ground-based 88S Traverse data, the elevation biases for ATM and the UAF lidar range from −9.5 to 3.6 cm, while surface measurement precisions are equal to or better than 14.1 cm. These results suggest that the ground-based GPS data and airborne altimetry data are appropriate for the validation of ICESat-2 surface elevation data.

Highlights

The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) is a next-generation laser altimeter developed by the National Aeronautics and Space Administration (NASA) and launched on 15 September 2018 (Markus et al, 2017)
precise point positioning (PPP) GPS post-processing methods are often used in regions where long-term base-station data are not available for Differential GPS (DGPS) methods, such as the center of ice sheets
While we are limited with respect to the availability of permanent GPS base stations for post processing, we feel confident that our methods provide consistent and accurate results and are appropriate for this data analysis

Summary

Introduction

The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) is a next-generation laser altimeter developed by the National Aeronautics and Space Administration (NASA) and launched on 15 September 2018 (Markus et al, 2017). ICESat-2 will continue NASA’s multidecade effort to measure changes in the polar regions (Markus et al, 2017; Webb et al, 2012; Zwally et al, 2011), with mission requirements that include the determination of the annual ice sheet elevation change rates to an accuracy of less than or equal to 0.4 cm a−1 (Markus et al, 2017). Plans for the post-launch validation of ICESat-2 elevation data products include utilizing both ground-based and airborne elevation datasets. The ground-based activities include the kinematic GPS validation efforts at Summit Station, Greenland (Brunt et al, 2017), and airborne activities, such as those associated with NASA’s Operation IceBridge (OIB; Koenig et al, 2010), which includes a lidar as part of the instrument suite

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Discussion

Conclusion