Analysis and Accuracy Assessment of a New Global Nearshore ICESat-2 Bathymetric Data Product

Although designed primarily for cryospheric science objectives, NASA's ICESat-2 satellite, which launched in 2018, quickly became recognized as the world's first spaceborne bathymetric lidar. Initially, there was no dedicated bathymetric data product for the mission, so researchers interested in using ICESat-2 bathymetry developed their own custom bathymetric signal extraction and correction algorithms. To address this product lack, in 2022, our study team began work on a new, dedicated ICESat-2 coastal and nearshore bathymetric data product, ATL24. Following the development and testing of the algorithms, ICESat-2 bathymetry was processed for the entire globe from the start of the mission in 2018 through present day, through a 13-day processing run. The goals of this study were twofold. First, we sought to leverage the global, full-mission processing run to compute and analyze metrics that provide insight into the global data set, ICESat-2's overall bathymetric mapping capabilities, and parameters that impact bathymetric measurement performance. Second, we assessed the accuracy of the ATL24 data product through comparison to higher-accuracy independent reference data at eight different sites with widely ranging seafloor morphologies and depth ranges. Collectively, the results of these two study phases are anticipated to assist researchers and practitioners in understanding ICESat-2's bathymetric mapping capabilities and in evaluating the utility of ATL24 for specific science and application use cases. We highlight this analysis through consideration of two example use cases. Finally, we conclude with a look ahead to anticipated future ATL24 enhancements and recommendations for ongoing science.