The Impacts of Ionosphere and Geomagnetic Field on GNSS Reflectometry Phase Delays

With the development of global navigation satellite systems (GNSS) and low Earth orbit (LEO) satellites, a number of space-based GNSS reflectometry (GNSS-R) missions have emerged. However, as a dispersive medium of the GNSS L-band signals, the ionosphere is a major error source of the GNSS-R products. The ionospheric error and its residuals are not negligible for the GNSS-R phase delays. A simulation study of the impacts of the ionosphere on GNSS-R phase delays, which accounts for the ionospheric electron density and geomagnetic field along the ray paths derived from NeQuick and IGRF12 models, respectively, has been conducted. The preliminary results showed that the ionosphere error and its residuals are increase with the increasing of the F10.7 index, and the first order errors can reach more than 20 meters, so the dual frequency measurements are needed, while the second order residual errors can reach 2.8 mm, which need further investigation.