Assessing the capability of Triton GNSS-Reflectometry for land surface hydrological monitoring

The number of spaceborne Global Navigation Satellite System-Reflectometry (GNSS-R) missions has increased in recent years due to their utility in monitoring geophysical parameters. Launched in October 2023, the Triton mission aims to demonstrate satellite bus technology while performing GNSS-R experiments. Although initial data have been applied to ocean wind speed retrieval, Triton’s performance over land remains largely unassessed. This study evaluates Triton’s capability to retrieve two key hydrological parameters over land, near-surface soil moisture and surface water extent, using data collected from November 2023 to December 2024. Since Triton lacks direct measurements of effective isotropic radiated power (EIRP), we calibrated the observations using lookup tables from NASA’s Cyclone GNSS (CYGNSS) mission. Linear regression analysis between Triton-derived surface reflectivity and Soil Moisture Active Passive (SMAP) soil moisture data demonstrates that Triton can effectively retrieve near-surface soil moisture when reflections are coherent. Furthermore, Triton reflections across the eastern United States exhibit clear sensitivity to surface water, indicating the mission’s potential for monitoring inundation and surface water extent.