风云三号C星GNOS北斗掩星电离层探测初步结果

利用风云三号卫星C星GNOS掩星探测仪电离层数据，分析了2013年10月FY-3C GNOS探测的北斗掩星电离层廓线分布，将2013年10月1日至2015年10月10日期间FY-3C GNOS观测的F₂层峰值电子密度（N_mF₂）与地面电离层测高仪观测结果进行对比，验证了FY-3C GNOS北斗电离层掩星的探测精度.结果表明，FY3-C GNOS北斗电离层掩星与电离层测高仪探测的N_mF₂数据相关系数为0.96，平均偏差为10.21%，标准差为19.61%.在不同情况下其数据精度有如下特征:白天精度高于夜晚；夏季精度高于分季，分季精度高于冬季；中纬地区精度高于低纬地区，低纬地区精度高于高纬地区； BDS倾斜同步轨道（IGSO）卫星精度高于同步轨道（GEO）卫星和中轨道（MEO）卫星.FY-3C GNOS北斗电离层掩星与国际上其他掩星电离层数据精度的一致性对GNSS掩星探测资料的综合利用具有重大意义. 

Beidou Navigation Satellite System Sounding of the Ionosphere from FY-3C GNOS:Preliminary Results

The world's first dual-system compatible Global Navigation Satellite System (GNSS) Occultation Sounder (GNOS) for Beidou Navigation Satellite System (BDS) and Global Positioning System (GPS) was successfully launched into orbit with FY-3C satellite on 23 September 2013, and a large number of ionospheric BDS Radio Occultation (BDSRO) data have been collected. The ionospheric BDSRO products observed by FY-3C GNOS are introduced firstly, then the distribution of ionospheric Electron Density Profiles (EDPs) in October 2013 is analyzed. Finally, the precision of ionospheric BDSRO data obtained by FY-3C GNOS is verified through F₂-layer peak electron density (N_mF₂) comparisons between BDSRO and ionosondes. The results show that the correlation coefficient ofN_mF₂ data between BDSRO and ionosondes is 0.96, the bias is 10.21% and the standard deviation is 19.61%, which is comparable with other international ionospheric occultation products based on GPS. The N_mF₂ precision of BDSRO has the following characteristics. Its precision at daytime is higher than that at nighttime, and its precision in summer is higher than that in equinox seasons, while the precision in winter is lowest. Moreover, its precision at mid-latitude region is higher than that at low-latitude region, and the precision at high-latitude region is lowest. The precision of BDS satellites on Inclined Geosynchronous Satellite Orbit (IGSO) is higher than that on Geosynchronous Orbit (GEO) and Medium Earth Orbit (MEO). The precision consistency of the ionospheric occultation product between BDS-FY-3C GNOS and other internationl occultation projects is of great significance for comprehensively utilizing the GNSS occultation observation data. With the continued deployment of FY-3 satellites and Beidou navigation satellites, GNOS can provide more ionospheric occultation data in the future, which will be helpful to the ionospheric research and space weather forecasting based on GNSS occultation observations.