Analysis of Ionospheric Delay Correction Model Performance During Geomagnetic Storms

Ionospheric delay, as one of the largest error sources in radio propagation, can only be corrected for this error using the ionospheric delay correction model for Global Navigation Satellite System (GNSS) single-frequency users. In this paper, the 2021 geomagnetic storm event is selected, and based on the measured ionospheric data from the GNSS observatory, the perturbation of the ionosphere by the geomagnetic storm event is analyzed, and it is found that the response of the ionosphere to the geomagnetic storm has obvious differences in the response characteristics and response time in different latitude regions. The performance of the global ionospheric map (GIM), the empirical model, and the broadcast ionospheric model during the geomagnetic storm-induced ionospheric perturbation is analyzed and the change in the accuracy of each ionospheric model during the geomagnetic storm-induced ionospheric perturbation is investigated, using the measured electron content of the GNSS as a benchmark. The results show that there is good agreement between the GIM products and the measured electron content during the period of ionospheric calm and the period of ionospheric perturbation. It is worth noting that geomagnetic storms do not necessarily lead to a decrease in the accuracy of ionospheric delay-correction models, and in some cases, the models that were originally under-accurate show a tendency to improve their accuracy during the period of perturbation instead. Neither the broadcast ionospheric model nor the electron content of the empirical model output responds to geomagnetic storm-induced ionospheric perturbations. The change characteristics of the ionosphere during geomagnetic storms are very complex. In this paper, we study the characteristics of ionospheric changes during geomagnetic storms and the performance of models during ionospheric perturbations. The results show that the ionospheric characteristics at different latitudes during geomagnetic storms are very different; and there is a phenomenon that the accuracy of the model correction is improved during the perturbation of geomagnetic storms. This paper provides a reference for improving the performance enhancement and application of ionospheric delay correction models. Ionospheric disturbances caused by geomagnetic storms have different spatial and temporal characteristics Global ionospheric map has the optimal performance in the calm period and the perturbation period The broadcast ionospheric model and the empirical model do not respond to ionospheric perturbations