An Assesment of GNOS Radio Occultation Data

GNOS (GNSS Occultation Sounder) is a radio occultation payload on board the Chinese FengYun-3 series satellites, which is capable of tracking both the signals of GPS and Beidou navigation satellite systems. The FY-3C and FY-3D satellite launched on 23 September 2013 and 15 November 2017, respectively. Now they have more than 1200 RO profiles daily, including approximately 900 GPS and 300 Beidou profiles. In this paper the GNOS data quality of FY-3C and FY-3D, including GPS and Beidou RO data, will be assessed. Then, the impacts of assimilating GNOS data in GRAPES, the operational numerical weather prediction model of China Meteorological Administration, will also be presented. The FY-3C is a morning-orbit satellite, and the FY-3D is afternoon-orbit satellite. Therefore, the orbit impact of RO on the analysis and forecast will be discussed.