An Introduction to the HydroGNSS GNSS Reflectometry Remote Sensing Mission

• Main Authors: Martin J. Unwin, Nazzareno Pierdicca, Estel Cardellach, Kimmo Rautiainen, Giuseppe Foti, Paul Blunt, Leila Guerriero, Emanuele Santi, Michel Tossaint
• Format: Article
• Language: English
• Published: IEEE 2021-01-01
• Series: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
• Subjects: Global navigation satellite system (GNSS); global navigation satellite system reflectometry (GNSS-R); hydrology; remote sensing
• Online Access: https://ieeexplore.ieee.org/document/9456091/

HydroGNSS (Hydrology using Global Navigation Satellite System reflections) has been selected as the second European Space Agency (ESA) Scout earth observation mission to demonstrate the capability of small satellites to deliver science. This article summarizes the case for HydroGNSS as developed during its system consolidation study. HydroGNSS is a high-value dual small satellite mission, which will prove new concepts and offer timely climate observations that supplement and complement the existing observations and are high in ESAs earth observation scientific priorities. The mission delivers the observations of four hydrological essential climate variables as defined by the global climate observing system using the new technique of GNSS reflectometry. These will cover the world's land mass to 25 km resolution, with a 15-day revisit. The variables are soil moisture, inundation or wetlands, freeze/thaw state, and above-ground biomass.