Analysis of ICESat-2 Data Acquisition Algorithm Parameter Enhancements to Improve Worldwide Bathymetric Coverage

A major advance in global bathymetric observation occurred in 2018 with the launch of NASA’s ICESat-2 satellite, carrying a green-wavelength, photon-counting lidar, the Advanced Topographic Laser Altimeter System (ATLAS). Although bathymetric measurement was not initially a design goal for the mission, pre- and post-launch studies revealed ATLAS’s notable bathymetric mapping capability. ICESat-2 bathymetry has been used to support a wide range of coastal and nearshore science objectives. However, analysis of ICESat-2 bathymetry in numerous locations around the world revealed instances of missing or clipped bathymetry in areas where bathymetric measurement should be feasible. These missing data were due to the ATLAS receiver algorithms not being optimized for bathymetry capture. To address this, two updates have been made to ICESat-2’s receiver algorithm parameters with the goal of increasing the area for which ICESat-2 can provide bathymetry. This paper details the parameter changes and presents the results of a two-phased study designed to investigate ICESat-2’s bathymetry enhancements at both local and global scales. The results of both phases confirm that the new parameters achieved the intended goal of increasing the amount of bathymetry provided by ICESat-2. The site-specific phase demonstrates the ability to fill critical bathymetric data gaps in open ocean and coastal settings. The global analysis shows that the area of potential bathymetry approximately doubled, with 6.1 million km2 of new area in which bathymetric measurements may be feasible. These enhancements are anticipated to facilitate a range of science objectives and close the gap between ICESat-2 bathymetry and offshore sonar data.