The results of analyzing the planetary and tidal variabilities in the mesosphere, thermosphere, and ionosphere acquired in calculations for January 2009 using two versions of the EAGLE model...

The work presents an analysis of changes in the correlation coefficient between the total electron content variations at magnetically conjugate points calculated based on global ionospheric maps under quiet geomagnetic conditions and for the strong geomagnetic storm of March 17, 2015, the St. Patrick’s storm. It is shown that there are extensive, high-latitude regions of significant correlation of the considered in variations during a geomagnetic storm at magnetically conjugate points. After a geomagnetic storm zones of anticorrelation of total electron content variations appear in magnetically conjugate regions. The calculated statistical relationships differ for global maps presented by different processing centers, but they retain common fundamental features. A comparison is also made of the correlation coefficients obtained from the results of model calculations of the global model of the upper atmosphere and from observational data.

This study presents a comprehensive analysis of the impact of Storm Laura, which was observed over Europe and the Baltic Sea on 12 March 2020, on the thermosphere–ionosphere system. The investigation of ionospheric disturbances caused by the meteorological storm was carried out using a combined modeling approach, incorporating the regional AtmoSym and the global GSM TIP models. This allowed for the consideration of acoustic and internal gravity waves (AWs and IGWs) generated by tropospheric convective sources and the investigation of wave-induced effects in both the neutral atmosphere and ionosphere. The simulation results show that, three hours after the activation of the additional heat source, an area of increased temperature exceeding 100 K above the background level formed over the meteorological storm region. This temperature change had a significant impact on the meridional component of the thermospheric wind and total electron content (TEC) variations. For example, meridional wind changes reached 80 m/s compared a the meteorologically quiet day, while TEC variations reached 1 TECu. Good agreement was obtained with experimental TEC maps from CODE (Center for Orbit Determination in Europe), MOSGIM (Moscow Global Ionospheric Map), and WD IZMIRAN (West Department of Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation Russian Academy of Sciences), which revealed a negative TEC value effect over the meteorological storm region.

The results of analysis of variations in the sporadic layer critical frequency (foEs) for winter periods of 2008–2010 in which sudden stratospheric warmings were observed are presented in the paper. The data were obtained at Kaliningrad ionospheric station (54.6° N, 20° E) by a Parus digital ionosonde under the usual sounding regime with an interval of 15 min. Daily mean values of foEs were used for the analysis. Solar and geomagnetic activity remained low during the periods under study, making it possible to relate the quasiwave time variations in foEs to the parameters of stratospheric warmings. The results of spectral analysis performed on the basis of continuous wavelet transform showed that, during all warmings occurring in 2008–2010, time variations in foEs show the presence of wave processes with a period of an order of 5 days and longer ones with a period of ~10—11 days. These periods coincide with characteristic periods of planetary waves observed in the atmosphere during sudden stratospheric warnings.

This paper presents the analysis of planetary waves and tidal variability during January 2009 in the mesosphere, thermosphere, and ionosphere simulated with two versions of the EAGLE model. It is shown that sudden stratospheric warming (SSW) occurred in January 2009 leads to an increase in the planetary and tidal wave activity in the lower thermosphere. The features of the solar-migrating and non-migrating components of tidal variations in the thermosphere, ionosphere, and electric fields are considered. The reproduction of the vertical electromagnetic drift during the SSW period over the Jicamarca station is explained by a significant increase in the diurnal and semi-diurnal tidal activity.