Effects of equatorial plasma bubble-induced ionospheric gradients on GNSS PPP-RTK

Abstract

Equatorial plasma bubble (EPB) exerts a severe threat to global navigation satellite system (GNSS) technique. It not only can lead to ionospheric scintillation, but also can create strong plasma gradients in ionosphere. In this study, we investigate the effects of EPB-induced ionospheric gradients on GNSS precise point positioning with real-time kinematic (PPP-RTK) technique for the first time. A common medium-scale EPB event occurred in ionosphere over the southern U.S. on May 28, 2017 is served as a case. The results show, during the period of the EPB event, the interpolated ionospheric residuals are very large with maximum 7.5 TECU without EPB correction while the counterparts are generally below 1 TECU with EPB correction. As for the 3D positions, EPB-induced ionospheric gradients mainly affect the initialization or re-initialization process of PPP-RTK solutions, which significantly increase the estimated errors and lengthen the convergence times. This study can help the GNSS community understand EPB’s impacts on GNSS PPP-RTK more deeply and provide support for its mitigation in the next work.