Monitoring Land Surface Hydrology Using Cygnss

The Cyclone Global Navigation Satellite System (CYGNSS) is a constellation of eight small satellites, each of which carries specialized GNSS receivers to record surface-reflected GNSS signals. The L-band signals recorded by CYGNSS have been shown to be sensitive to land surface hydrologic variables, including near-surface soil moisture and inundation extent. However, given certain conditions-such as vegetation cover and surface roughness, CYGNSS observations may be more or less sensitive to these variables. The pseudo-random sampling strategy used by CYGNSS presents new opportunities but also new challenges to the monitoring of land surface hydrology. This work, using South America as a case study, quantifies the ability of CYGNSS to monitor soil moisture and inundation extent for different vegetation and roughness conditions and describes how these measurements could be used to sense changes in surface hydrology over time.