Magneto‐ionic polarization and GPS signal propagation through the ionosphere

Abstract

Recent progress in high‐precision GPS measurements research and applications leads to the study of higher‐order ionosphere effects on GPS signal propagation. This paper focuses on second‐order ionospheric effects, which are influenced by the presence of the Earth's magnetic field. Due to the presence of Earth's magnetic field, GPS signals may propagate through the ionosphere in two distinct modes: the ordinary mode and the extraordinary mode. These two modes correspond to different refractive indices, and the difference between these refractive indices affects the computation of the second‐order error introduced by the ionosphere to GPS code and carrier phase approximations. The first objective of this paper is to clarify a misconception about the different modes of GPS signal propagation through the ionosphere: although the GPS signal is predominantly right‐hand circularly polarized, it may propagate through the ionosphere in either the ordinary or the extraordinary mode. The second objective of this paper is to analyze the impact of the different modes of propagation on GPS solutions at different geographical locations.