LIU CongLiang,
SUN YueQiang,
DU QiFei et al
.2020.Ground-based GNSS VTEC constrained ionospheric correction method for atmospheric occultation Chinese Journal of Geophysics(in Chinese),63(12): 4324-4332,doi: 10.6038/cjg2020O0147
Ground-based GNSS VTEC constrained ionospheric correction method for atmospheric occultation
LIU CongLiang1,2,3,4, SUN YueQiang1,2,3,4, DU QiFei1,2,3,4, BAI WeiHua1,2,3,4, WANG XianYi1,2,3,4, LI Wei1,2,3
1. National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China; 2. Beijing Key Laboratory of Space Environment Exploration, Beijing 100190, China; 3. Joint Laboratory on Occultations for Atmosphere and Climate(JLOAC), Beijing 100190, China; 4. School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：Ionosphere is a major error source of Global Navigation Satellite System (GNSS) radio occultation (RO), this paper proposed a ground-based GNSS vertical total electron content (VTEC) constrained ionospheric error correction method, which accounts for the ionospheric asymmetry along the occultation ray path as well as the first- and second-order ionospheric terms. It combines the ground-based GNSS VTEC horizontal change information and the ionospheric model vertical change information to estimate the electron density along the occultation ray path, then calculates the bending angle first- and second-order ionospheric error profiles under the assumption of bilateral local spherical symmetry along the inbound side and outbound side rays. The GNSS RO bending angle first- and second-order ionospheric error profiles was calculated using MetOp-A and GRACE missions observation data and international GNSS service (IGS) GNSS VTEC data from a low solar activity day (i.e., July 15, 2008) and a high solar activity day (i.e., July 15, 2013). The comparative analysis shows that the empirical model consistent with the theoretical model in terms of the second-order Residual Ionospheric Error (RIE) and with the observation data in terms of the first- and second-order bending angle ionospheric errors. Therefore, this method can be used for those RO events with low quality L2 observations and even loss of L2 signal, to correct the first- and second-order ionospheric errors to improve the bending angle accuracy and the RO observations utilization.
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