Vertical accuracy of satellite-derived bathymetry developed using ICESat-2 ATL03 data for Brazilian coastal waters

Satellite-Derived Bathymetry (SDB) offers a cost-effective solution for mapping and monitoring coastal environments, especially where in situ data are limited or outdated. The ICESat-2 mission, through its ATL03 photon-counting lidar product, provides high-resolution geolocated photon data suitable for depth retrieval in optically shallow waters. This study evaluates the vertical accuracy of ATL03-derived depths along four tropical coastal regions of Brazil by comparing photon returns, corrected for geophysical effects and empirical refraction, with reference depths from nautical charts referenced to Mean Sea Level (MSL). Accuracy metrics including RMSE, MAE, R², and Lin’s Concordance Correlation Coefficient (LCCC) were employed for each region and acquisition. Results showed the best performance in Pernambuco and Rio de Janeiro, with RMSE values between 1.04 and 1.38 m. In contrast, Ceará and Rio Grande do Norte displayed larger discrepancies. These regional differences may reflect variations in local environmental conditions, seabed characteristics, and the representativeness of available reference data, which can affect photon penetration and bottom detection. Subtrack-level analysis revealed considerable variability among ICESat-2 beams, highlighting the importance of individualized assessment and beam selection. Overall, ICESat-2 ATL03 data proved viable for bathymetric mapping in Brazilian coastal waters, with reliable performance to depths of 17–24 m, providing a critical baseline for future SDB research and operational applications.