Analysis of the Ionospheric Response to Sudden Stratospheric Warming and Geomagnetic Forcing over Europe during February and March 2023

Abstract

A study of the behavior of the main characteristics of the ionosphere over Europe during the 26–28 February 2023 ionospheric storm was carried out in this present work. The additional influence of sudden stratospheric warming on the ionosphere was considered. The behavior of the critical frequency of the ionosphere foF2 (characterizing the maximum electron density), the peak height of the F2-layer (hmF2), and Total Electron Content (TEC) were investigated through their relative deviations from the quiet conditions. The behavior of the TEC over Europe showed the geographic latitudinal dependence of the response. The variability in the ionospheric critical frequency was represented by the data of 10 ionospheric stations for vertical sounding located in two groups: (i) near the prime meridian and (ii) near the 25° E meridian. Some differences were found in the response compared to the TEC response, which was explained by the different responses of the top maximum region and bottom maximum region. The peak height of the F2 layer varied strongly during the storm, which was due to the forced drift of ionospheric plasma induced by additional electric fields. The present detailed analysis of the ionospheric response shows that the considered storm exhibited characteristic features inherent in the winter season but with some manifestations of reactions in equinox conditions.

Seasonal Features of the Ionospheric Total Electron Content Response at Low Latitudes during Three Selected Geomagnetic Storms

“…Similarly, in this storm, a strong response is observed in the winter hemisphere. The SPW1 activation on 23 June 2015 has maxima at 40 • S and at the equator, with a larger amplitude in the Southern Hemisphere, confirming the well-known seasonal response in winter conditions [28,29].…”

“…Similarly, in this storm, a strong response is ob served in the winter hemisphere. The SPW1 activation on 23 June 2015 has maxima at 40 S and at the equator, with a larger amplitude in the Southern Hemisphere, confirming th well-known seasonal response in winter conditions [28,29]. In order to make an analogous study of the maximum manifestation of the TEC response in Figure 9, the amplitude and phase maps of SPW1 are presented.…”

“…This gives us reason to consider that the increase in electron density (respectively, TEC) in the auroral region is due to additional ionization from particles precipitation of the solar wind entering the atmosphere. The effect is strong in the winter hemisphere due to the low electron density in winter during nighttime conditions [2,28,29,41,44].…”

“…Based on this methodology, results were obtained for the solar activity impact on the Earth's upper atmosphere and ionosphere [26], as well as investigations of the climate of the upper atmosphere [27]. The use of the relative deviation from monthly median values characterizing quiet conditions allows us to estimate the type of ionospheric response in the conditions of geomagnetic storms [28,29]. The relative deviation is calculated using the following formula:…”

Trailing Equatorial Plasma Bubble Occurrences at a Low-Latitude Location through Multi-GNSS Slant TEC Depletions during the Strong Geomagnetic Storms in the Ascending Phase of the 25th Solar Cycle

“…The possible plasma bubble occurrences for selected geomagnetically disturbed days, whose Dst index (Dst < −100 nT) falls in the category of strong geomagnetic storms under the ascending phase of Solar cycle 25, are investigated using the sTEC depletion characteristics. Based on the above criteria, only four storm days, namely 27 February, 23 and 24 March and 23 April 2023 (referring to three geomagnetic storm events), are chosen for analysis in this study [80]. Figure 3 presents the variation of interplanetary and geomagnetic indices (IMF Bz, Dst, ap, and Kp) for the chosen storm days.…”