The Fengyun-3 GNOS Ionospheric Radio Occultation Mission: Accuracy Evaluation, Data Application and Potential Prospects of Network Observations

As an emerging detection technology, the Global Navigation Satellite System (GNSS) Radio Occultation (RO) technique can provide ionospheric observable profiles. China launched the FengYun 3C satellite (FY-3C) in 2013, which carried the GNSS Occultation Sounder (GNOS), the first RO sounder capable of simultaneously receiving the Global Positioning System (GPS) and the BeiDou Navigation Satellite System (BDS) signals globally. In the evaluation of the GNOS ionospheric products, the correlation coefficient and standard deviation of F2-layer maximum electron density (NmF2) between GNOS and COSMIC are 0.95 and 17.48%, respectively. The bias of maximum ionospheric scintillation index (S4max) between FY3C-GNOS and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) is 0.004. In addition, the ionospheric products of GNOS have also been taken into preliminary scientific applications in space weather monitoring, IRI model validation, climatology research, and study of ionospheric sporadic E layer. With the successive network observations of subsequent satellites in the FY3 series, it is bound to bring the massive RO data into more significant scientific values.