风云三号C星全球导航卫星掩星探测仪首次实现北斗掩星探测∗

摘要

The radio occultation (RO) technique using signals from the global navigation satellite system, is widely used to ob-serve the atmosphere for applications such as numerical weather prediction (NWP) and global climate monitoring. Since 1995, there have been turborogue sounder on board global positioning system/meteorology, black jack sounder on board challenging minisatellite payload and gravity recovery and climate experiment, IGOR sounder on board constellation observing system for meteorology, ionosphere and climate, GRAS on board meteorological operational, which have been receiving a large number of RO data, but their observed signals come only from global positioning system (GPS). These RO data have been wildly used in NWP and climate monitoring, however they cannot meet the requirements for high accuracy and real time atmosphere observation, in this case compatible RO sounder to obtain more RO observations is significant. Global navigation satellite system occultation sounder (GNOS) on board the fengyun3 C (FY3 C) satellite, which is the first Bei Dou system (BDS)/GPS compatible RO sounder in the world, was launched on 23 September 2013. Up to now, lots of RO observations have been obtained. In this study, the components of GNOS are introduced;one-day GNOS RO events and their global distribution are analyzed; compared with the GPS RO observations, the accuracy and consistency of BDS real-time positioning results and BDS RO products are analyzed. The preliminary results show that the BDS can enhance the number of RO events by 33.3%; the average deviation and standard deviation of BDS real time positioning results are 6 m and 7 m, respectively; the BDS/GPS difference standard deviation of reflectivity, temperature, humidity, pressure and ionospheric electron density are lower than 2%, 2 K, 1.5 g/kg, 2%, and 15.6%, respectively. The BDS observations/products are consistent with those of GPS, therefore BDS RO products can bring benefit to numerical weather prediction and global climate change analysis.%全球导航卫星掩星探测仪(GNOS)是国际首台北斗系统(BDS)和全球定位系统(GPS)双系统兼容掩星探测仪,2013年9月23日随风云三号卫星C星(FY3 C)发射入轨,目前已测得大量掩星数据.介绍了FY3 C-GNOS的组成；统计了2013年10月12日全天的FY3 C-GNOS掩星事件及其全球分布情况；通过与GPS精密定轨结果进行对比分析,测试了BDS在轨实时定位精度,检验了BDS掩星产品的可靠性和一致性.初步分析结果表明：14颗BDS卫星在轨运营的条件下, BDS和GPS兼容掩星探测仪可将掩星事件数提高约33.3%；BDS实时定位平均偏差优于6 m,标准偏差优于7 m；5—25 km高度范围内, BDS与GPS内符合精度大气折射率优于2%,温度优于2 K,湿度优于1.5 g/kg,压强优于2%,电离层峰值密度优于15.6%. GNOS的在轨正常运行及BDS与GPS掩星定位精度及反演产品的一致性为北斗掩星探测的业务化运行奠定了基础.