ICESat-2 Bathymetry: Advances in Methods and Science

Since the 2018 launch of NASA's ICESat-2 mission, one capability of its Advanced Topographic Laser Altimeter System (ATLAS) that has far exceeded expectations is bathymetric measurement. Although ICESat-2 was designed to generate surface-specific along-track and gridded data products, bathymetry was not a pre-launch science requirement of the mission. However, since launch, ATLAS has proven capable of bathymetric measurement to >40m in very clear waters [1], and ICESat-2 bathymetry is being used in a growing number of science disciplines. Post-launch efforts have focused on bathymetric signal classification (sea surface, water column and seafloor) and correction for refraction at the air-water interface. Because ATLAS provides bathymetry only along discrete tracks, another area of focus is on integration of ATLAS data with relative bathymetry from multispectral satellite imagery-often referred to as satellite-derived bathymetry (SDB)-to obtain spatially-contiguous 2D bathymetric coverage. This paper synthesizes the latest algorithms, techniques and uses of ICESat-2 bathymetry, including collaborative efforts of the Bathymetry Working Group of the ICESat-2 Science Team, and recommends topics for future investigation.