GNSS Reflectometry

Global Navigation Satellite System Reflectometry (GNSS-R)

The COSMIC program has most often been associated with the GNSS-Radio Occultation technique. However, COSMIC  also conducts research in spaceborne GNSS-Reflectometry (GNSS-R). 

GNSS-R is a satellite remote sensing technique that uses surface-reflected GNSS signals  to infer information about the Earth’s surface. The reflected GNSS signals act as a bistatic remote sensing radar that responds  to changing surface conditions. 

Reflected GNSS signals can be received onboard a low Earth orbiting satellite and used to estimate environmental conditions over the ocean, land, and sea ice.




Much of  COSMIC’s GNSS-R research  uses data from NASA’s Cyclone GNSS (CYGNSS) mission, which is a constellation of eight small GNSS-R receivers that are orbiting the tropics. 

CYGNSS was designed to retrieve wind speed over the ocean during hurricanes and tropical storms. However, the data are also sensitive to  both near-surface soil moisture and flood inundation extent over land. 

Researchers in COSMIC are developing retrieval algorithms, calibrating the data, and designing new GNSS-R receivers to expand the use  of GNSS-R as a burgeoning remote sensing technique.

Global inland water body map

Chart highlighting SMAP retrievals

Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) revisions for: