Grazing Angle GNSS-R for Earth Surface and Ionosphere Monitoring

Spaceborne grazing angle GNSS reflectometry (GNSS-R) utilizes GNSS signals reflected off Earth surface and received by low Earth orbiting (LEO) satellites with side- or downward-looking antennas. Grazing angle GNSS-R signals may contain sufficient coherent energy to enable the precise carrier phase retrieval. This presentation will focus on the latest progress in high precision spaceborne grazing angle GNSS-R technologies and applications that rely on processing of coherent reflection signal carrier phase observables. Coherent signal detection and phase estimation and filtering algorithms will be highlighted. Real grazing angle GNSS-R data collected from Spire Global CubeSats since 2020 have been processed to showcase GNSS-R applications in retrieving surface water content, atmospheric water vapor, mesoscale ocean surface patterns, sea ice extent detection, ice shelf surface structures and roughness, rivers and lakes boundary masks and surface height variations, and ionosphere total electron content and disturbances over polar and equatorial areas for space weather and natural hazardous event monitoring. Challenges in real-time GNSS-R implementations will also be addressed.