Global Ionospheric Response to the Geomagnetic Storms from March to April 2023

By using the global ionospheric data provided by IGS, the sliding quartile range method is employed to study the ionospheric disturbances during the two geomagnetic storms occurred from March to April 2023, striving to provide theoretical basis for the distribution characteristics of ionospheric disturbances caused by geomagnetic storms under strong solar radiation background during the peak year of solar activity. Results show that both geomagnetic storms were caused by the CMEs generated on the surface of the Sun facing towards the Earth, which reached the Earth and triggered an increase in the velocity of the interstellar solar wind. The CMEs carried a southward magnetic field component and high-energy particles, causing magnetic reconnection with the Earth’s magnetic field and triggering geomagnetic disturbances. When other factors such as dark stripe bursts are superimposed on the coronal mass ejections, the intensity of geomagnetic storms are enhanced, causing significant differences in the occurrence and distribution characteristics of ionospheric TEC disturbances. The geomagnetic storm that occurred on 23－24 April 2023 was affected by the superposition of dark bars and CMEs, resulting in a stronger intensity and longer duration of the April geomagnetic storm. At the same time, there are significant differences in the occurrence process and distribution characteristics of ionospheric disturbances caused by two geomagnetic storms. The ionospheric disturbances during the March showed an asymmetric distribution in an east-west direction, while the entire process of ionospheric disturbance during the geomagnetic period in April exhibits a transition from positive phase disturbance to negative phase disturbance. Additionally, in the East Asia-Australia (120°E), the ionospheric TEC in the Northern Hemisphere line is significantly higher than that in the Southern Hemisphere. The amplitude changes of ionospheric disturbances are most significant during the recovery phase of geomagnetic storms, showing a distribution pattern of positive disturbances at low latitudes and negative disturbances at middle-high latitudes.