Global Navigation Satellite System Reflectometry (GNSS-R)

GNSS-R is a satellite remote sensing technique that uses surface-reflected GNSS signals (such as the widely used GPS constellation) to infer information about the Earth's surface. The reflected GNSS signals act as a bi-static remote sensing radar with the reflected signal power responding to changing surface conditions. Reflected GNSS signals can be received on-board a low Earth orbiting satellite and used to estimate environmental conditions over ocean, land and sea ice.

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The NASA CYGNSS eight satellite constellation and the UK TechDemoSat-1 satellite both carry GNSS-R receivers capable of making ocean, land and ice observations, which are available to the public. The figure below shows GPS reflections recorded by CYGNSS during one 24-hour period.

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