An improved high precision ionospheric total electron content modeling using GPS

Space-based radio navigation systems such as the Global Positioning System (GPS) can provide us with a unique opportunity to study the effect of the ionosphere as the signals propagate from the satellites to the GPS receivers. Based on a modified version of the University of New Brunswick´s (UNB) DIPOP software package, the authors enhanced the algorithm to model ionospheric total electron content (TEC) using dual frequency GPS observations from stations of the International GPS Service (IGS). The algorithm uses a spatial linear approximation of the vertical TEC above each IGS station using stochastic parameters in a Kalman filter estimation to describe the local time and geomagnetic latitude dependence of the TEC. The authors demonstrate that the enhanced UNB algorithm in conjunction with an IRI-95 update procedure is capable of modeling the diurnal variation of TEC even during a solar storm period in the low latitude region using a higher order surface estimation technique for each GPS station processed