The GRAS SAF Project - an Operational Radio Occultation System

Frans Rubek, Georg Bergeton Larsen and Josep M. Aparicio

Abstract:	The EUMETSAT network of Satellite Application Facilities (SAFs) will, together with the EUMETSAT central facilities, constitute the future ground segments for EUMETSATs MSG and EPS/Metop satellites. SAFs are located in national meteorological offices or other approved institutes of EUMETSAT member states. The scope of the SAF activities will be to deliver products and/or software to derive these products, at the level of meteorological parameters, based primarily on the satellite data. The Global Navigation Satellite System (GNSS) Receiver for Atmospheric Sounding (GRAS) Meteorology SAF (hereafter the GRAS SAF) will receive raw and preprocessed GPS radio occultation data from the GRAS instrument onboard the EPS/Metop satellite, process these into vertical profiles of refractivity, temperature, pressure, and humidity, and distribute these products continuously to numerical weather prediction (NWP) and climate monitoring users. The GRAS SAF products promise globally distributed high-vertical resolution data on a 24 hour-basis, forming a considerable improvement on today’s measurement methods regarding coverage, vertical resolution, frequency, and cost. A second objective of the GRAS SAF is to supply software for 4DVAR-assimilation of radio occultation data into numerical weather prediction models. The main users of the GRAS SAF products will be meteorologists doing data assimilation, and users from the climate research and atmospheric science communities, needing comprehensive, globally distributed temperature, pressure, and humidity information. The products will come in two types: • Near-Real Time Products, disseminated less than three hours after acquisition (primarily for NWP use) • Improved Offline Products, available less than 30 days after acquisition (primarily for climate research use)
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	526 - 531
Cite this article:	Rubek, Frans, Larsen, Georg Bergeton, Aparicio, Josep M., "The GRAS SAF Project - an Operational Radio Occultation System," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 526-531.
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