Precise Estimation of Phase Center Variation of the Onboard GPS Antenna and Its Influence on POD for COSMIC-2

Abstract

COSMIC-2 occultation meteorological observations can provide meteorological information at 50 degrees north and south latitudes to improve the accuracy of weather forecasting, especially for extreme weather (such as typhoon and rainstorm) forecasting. In order to ensure the smooth operation of COSMIC-2 satellite mission, it is necessary to achieve the precise orbit determination (POD) of COSMIC-2. In the processing of satellite borne GPS data, the error source of receiver antenna phase center error is very important. Based on GPS observation data, in orbit correction of the phase center variation (PCV) of the COSMIC-2 satellite borne GPS receiver antenna can improve the accuracy of satellite orbit determination. In this study, the PCV model is estimated in orbit using two methods, the direct method and the residual method, and the obits of COSMIC-2 satellites are determined by reduced dynamic method using the onboard GPS data. The orbit overlap comparison and the reference orbit comparison are used to evaluate the internal and external conformity accuracy, respectively, and the impact of the PCV model estimated by two methods on its precision orbiting are analyzed and compared. The results show that the orbit overlap validation accuracy is better than 1.27cm, 2.07cm and 1.05cm in radial (R), tangential (T) and normal (N) directions, respectively, and the root mean square (RMS) value in three-dimensional (3D) direction does not exceed 2.57cm without PCV model; the reference orbit comparison accuracy is better than 9.97cm, 13.34cm and 4.77cm in R, T and N directions, respectively, and the RMS value in 3D direction does not exceed 17.51cm. After adding the PCV models estimated by the direct method and the residual method, the RMS values of the orbit overlap comparison have the accuracy improvements of 2.5mm and 1.3mm in the 3D direction, and the RMS values of the reference orbit comparison are improved by 1.1mm and 2.1mm in the 3D direction, respectively.