Study of Chinese regional ionospheric TEC response to magnetic storms during April 23–25, 2023

We present the ionospheric responses over China during the magnetic storm on April 21–27, 2023. The ionospheric responses are investigated by using two-dimensional Global Navigation Satellite System (GNSS) TEC images and Beidou Navigation Satellite System (BDS) geostationary earth orbit (GEO) TEC which are obtained from the Crustal Movement Observation Network of China (CMONOC) and Yunnan Continuous Operational Reference System (CORS), respectively. The results show that the response of ionospheric TEC to magnetic storm occurs 2.4 h after the main phase of magnetic storm. A group of disturbances are found in the main phase of magnetic storm, and two groups of disturbances are found in the recovery phase. The maximum disturbance amplitude can reach 0.3 TECU. At the same time, we present that the disturbance in the main phase of the magnetic storm propagates westward at ~ 639.0 km/h. During the magnetic storm recovery phase, the first group of disturbances propagates from north to south at a speed of ~ 416.0 km/h, and the second group of disturbances propagates at a speed of ~ 218.1 km/h along the azimuth of 124.7°. The study also shows that the ionospheric negative storm caused by the magnetic storm is related to the thermosphere storm circulation. GUVI O/N₂ ratio data and the change of critical frequency variations in the F2 layer (foF2) further prove the evolution of the ionospheric negative storm.