Model analysis method (MAM) on the effect of the second-order ionospheric delay on GPS positioning solution

Abstract

In this paper, we develop an approach to study the effect of second-order ionospheric delay on GPS positioning based on the ionosphere-free combination (abbreviated to Lc) of GPS dual-frequency carrier phase observables, in which the first-order ionospheric delay has been eliminated. GPS data from IGS WUHN tracking station during April 9–23, 2003 is used to perform the above approach, and results show that the second-order ionospheric delay in GPS so-called ionosphere-free observables will result in the regular southward shift of GPS positioning solution. Additionally, the influence of the Earth’s magnetic field on second-order ionospheric delay over the Wuhan area is discussed, and it indicates that the Earth’s magnetic field is one of the main factors why second-order ionospheric delay results in the regular southward shift of GPS positioning solution over Wuhan area.