Earth’s Ionospheric Response to Solar Activity Phenomena in February–March 2023

As a result of the analysis of data from vertical and oblique sounding of the ionosphere in February–March 2023 using the new ionospheric index, it was found that solar coronal mass ejections (CMEs) of the loop type lead to a long-term decrease in the critical frequencies F-layer of the ionosphere, while other types of CMEs may not lead to significant changes in the state ionosphere. The possible role of high-speed streams of solar wind and energetic protons in the occurrence of ionospheric disturbances is noted. Distance–frequency characteristics of the Cyprus–Nizhny Novgorod route during geomagnetic disturbances are given, which indicate both a strong deformation of the F-layer of the ionosphere and the appearance of z-shaped wave disturbances propagating to a region of lower altitudes.