利用FY3C与FY3D GPS掩星资料研究中低纬地区偶发E层形态的比较  

Comparison of the Morphologies of Sporadic E Layers Derived Using GPS Radio Occultation Data from FY3C and FY3D Satellites

作　　者：罗佳[1,2] 徐晓华[1] LUO Jia;XU Xiaohua(School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China;Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,Wuhan 430079,China)

机构地区：[1]武汉大学测绘学院,湖北武汉430079 [2]地球空间环境与大地测量教育部重点实验室,湖北武汉430079

出　　处：《武汉大学学报（信息科学版）》2022年第10期1775-1784,共10页Geomatics and Information Science of Wuhan University

基　　金：国家自然科学基金(42074027,42174017)。

摘　　要：偶发E层(sporadic E,Es)是主要发生在90~120 km高度的电子密度显著增强的电离层薄层,Es层的存在会导致掩星观测中全球导航卫星系统信号强度和相位的强烈波动。利用2019-01—2021-12风云三号C(Fengyun-3C,FY3C)和风云三号D(Fengyun-3D,FY3D)卫星GPS(global positioning system)掩星观测的50Hz信噪比数据提取Es层信息,进而对两颗卫星数据分别反演得到的60°S~60°N中低纬地区Es层发生率的时空分布及季节变化进行比较。结果发现,虽然两颗卫星掩星资料得到的Es层发生率分布形态基本一致,均反映了Es层的发生率与地磁场和中性大气背景风场的相关性,但在大部分季节和地区,由FY3D得到的Es层发生率低于由FY3C得到的结果,北半球夏季中纬地区尤为明显,而FY3C反演结果与基于电离层与气候星座观测系统掩星数据的反演结果更为接近。导致差异的可能原因包括两颗卫星信噪比廓线的上边界高度分布和地方时覆盖上的差异、两颗卫星掩星接收机噪声水平的差异等。上述结果表明,后续融合两颗卫星的掩星数据进行Es层相关研究时,可能需要顾及两颗卫星接收机的不同噪声水平,在Es层发生的判定策略上进行针对性调整。Objectives: Sporadic E(Es) layers, the thin layers with enhanced electron density sporadically appearing at the altitude range of 90 to 120 km, can cause strong fluctuations in the amplitudes measurements of global navigation satellite system(GNSS) radio occultation(RO).Methods: We use the 50 Hz signal-to-noise ratio(SNR) data of global positioning system(GPS) RO observations from the Fengyun-3C(FY3C) and Fengyun-3D(FY3D) satellites to detect the existences of Es layers, based on which the spatiotemporal distributions and seasonal variations of Es occurrences at the latitudes of 60°S-60°N during 2019-01 to 2021-12 are derived and compared.Results: It is found that the Es morphologies derived using the RO data from the two satellites independently are basically in accordance with each other, which both reflect the close relationships of the Es occurrences with the geomagnetic field and the neutral wind field.While the Es occurrences derived from FY3C are generally higher than those derived from FY3D in most seasons and over different regions, which is especially distinct in the summer season of the middle latitudes over the northern hemisphere, and the FY3C-derived Es morphology is more consistent with previous studies based on COSMIC(the constellation observing system for meteorology,lonosphere,and climate) RO data.Conclusions: Several factors should contribute to the differences between the Es morphologies derived from the RO observations of the two satellites, including the differences in the top heights of the SNR profiles, the differences in the local time coverages of the RO observations from the two satellites, and the different noise levels of the global navigation occultation sounders(GNOSs) on the two satellites. Our results indicate that the Es detection strategy might need to be adjusted according to the noise level of the GNOSs when combining the RO data from two satellites.

关 键 词：偶发E层 FY3C FY3D 掩星 

分 类 号：TN967.1[电子电信—信号与信息处理]