Post-midnight impact of ionospheric irregularities on GPS based kinematic precise point positioning

Abstract The kinematic precise point positioning (KPPP) is one of the best techniques aiming for zero-difference precise positioning. Recent studies have shown a growing use of KPPP in several kinematic platform-based applications for precision approach. This study therefore aims to explore the impact of the ionospheric plasma density perturbations on the KPPP, which bear significant effect over the global equatorial and low latitude belt. With a unique data set of simultaneous observations from a reference station and a close-by scintillation monitoring station located within Hyderabad in India, a study of impact of post-midnight scintillations on KPPP is performed. A 4-year duration around peak of the solar cycle 24 between 2013 and 2016 is considered for KPPP analysis by GipsyX software using continuous observations. The daily ENU (east, north, up) residuals are obtained by subtracting the monthly mean precise position from the daily 30-s sampled KPPP estimates. Then the nighttime ENU residuals (between 18:00 and 06:00 Indian standard time, IST) are segregated into pre-midnight (18:00 to 00:00 IST) and post-midnight (00:00 to 06:00 IST) intervals for all the nights. Owing to a different nature of post-midnight irregularities over the equatorial and low latitudes, the results are obtained for post-midnight KPPP. The amplitude scintillation index S4 is obtained for the corresponding nights for all the days and simultaneous records are used to obtain a few case studies of very high ENU residuals reaching up to 20 m in some cases. Also, the statistical analysis of the ENU shows a decreasing trend in the amplitude of ENU perturbations from midnight to morning hours, wherein, maximum perturbations are observed from 00:00 to 01:00 local time. Conclusions are presented in comparison with the previous literature, and it is found that this could possibly be the first report of the post-midnight impact of the ionospheric scintillation on the KPPP over Indian region.