[G06-5] GNSS reflectometry

[G06-5-06] GNSS Reflectometry onboard the International Space Station with GEROS-ISS: Review of activities and current status

^○Jens Wickert^{1, 2}, Estel Cardellach³, Manuel Martin-Neira⁴, Ole Andersen⁵, Jorge Bandeiras⁶, Laurent Bertino⁷, Adriano Camps⁸, Jan Saynisch¹, Nuno Catarinho⁶, Christine Gommenginger¹⁰, C. K. Shum¹⁴, Cinzia Zuffada¹², Giuseppe Foti¹⁰, Jiping Xie⁷, Per Hoeg⁵, Adrian Jaeggi¹¹, Michael Kern⁴, Tony Lee¹², Maximilian Semmling¹, Hyuk Park⁸, Nazzareno Pierdicca¹³ (1.GFZ Potsdam, Germany, 2.Technische Universitaet Berlin, Germany, 3.IEEC/ICE-CSIC, Institute of Space Sciences, Barcelona, Spain, 4.European Space Agency, ESTEC, Noordwijk, The Netherlands, 5.Technical University of Denmark, Copenhagen, Denmark, 6.DEIMOS Engenharia, Lisbon, Portugal, 7.Nansen Environmental and Remote sensing Center, NERSC, Bergen, Norway, 8.IEEC/CTE-UPC, Center for Space Technologies, Barcelona, Spain, 9.Ifremer, Paris, France, 10.National Oceanography Center, Southampton, U.K., 11. University Bern, Switzerland, 12. Jet Propulsion Laboratory, Pasadena, Caltech, USA, 13. Sapienza University of Rome, Italy, 14. Ohio State University, Columbus, USA, 15. Collecte Localisation Satellites, Ramonville St-Agne, France)

GEROS-ISS is an innovative ISS experiment of the European Space Agency (ESA) primarily focused on exploiting reflected signals of opportunity from Global Navigation Satellite Systems (GNSS) at L-band to measure key parameters of ocean surfaces.
The primary mission objectives are: (1) to measure the altimetric sea surface height of the ocean using reflected GNSS signals and (2) to retrieve scalar ocean surface mean square slope (MSS), which is related to sea roughness, wind speed and direction.
Secondary mission objectives are related to further explore the potential of GNSS radio occultation data for global atmospheric sounding and to assess the potential of GNSS scatterometry for land applications.
Two competitive industrial phase A studies were completed in 2016, complemented by the international scientific study GARCA (GNSS-R – Assessment of Requirements and Consolidation of Retrieval Algorithms) to develop an End2End Simulator for the preparation of the GEROS-Mission and to perform Observing-System Simulation Experiments (OSSE) to assess the oceanographic significance of the expected GEROS-ISS measurements. In parallel to these studies dedicated flight campaigns were carried out to monitor the sea surface height of the Baltic Sea around Helsinki, Finland utilizing the interferometric GNSS-Reflectometry approach, which is planned to be implemented for GEROS.
GEROS was originally foreseen to be launched in 2019. Following the Phase A industrial contracts and the parallel scientific study, ESA is now leading a mission reduction exercise aimed at bringing its cost significantly down while keeping the most essential scientific objectives. We review the activities related to the GEROS-ISS experiment and inform on the recent mission status.