Search

We present the results of observations of variations in the mid-latitude ionospheric parameters and physical processes in the geospace during March 20, 2015 partial solar eclipse over Kharkiv (49.60° N, 36.30° E) where the eclipse magnitude was about 0.54. The Kharkiv incoherent scatter (IS) radar and digital ionosonde were used for ionospheric observations and estimations of the parameters of the thermal and dynamical processes. At the time of the maximum obscuration of the Sun's area, an increase in the ionospheric F2 peak height by about 40 km was observed. At the same time, the electron density at altitudes of 190 and 210 km decreased by approximately 18.5 and 16.5%, respectively. During the eclipse, a decrease in the electron temperature and apparent changes in the vertical plasma drift velocity were observed. The observations and analysis have shown that the solar eclipse led to significant restructuring of the thermal and dynamic state of the ionospheric plasma over Kharkiv.

The equipment and methodical characteristics of determining the vertical component of the ionospheric plasma motion velocity Vz based on an incoherent scatter radar of Institute of Ionosphere, National Academy of Sciences and Ministry of Education and Science of Ukraine (Kharkiv), which is the only radar of such type in Central Europe, are described. Based on the radar data, the patterns of altitude and diurnal variations in Vz near the maximum of solar cycle 24 for the typical geophysical conditions (around the summer and winter solstices, the spring and fall equinoxes) at low geomagnetic activity and the specifics of these changes during ionospheric storms are presented. The results of modeling of the dynamic processes in ionospheric plasma under the conditions of the undisturbed ionosphere, including the determination of altitudetime variations in the thermospheric wind velocity, are presented. It has been established that this velocity can significantly differ from the thermospheric wind velocity calculated by the known empirical global models. This difference is likely related to the regional features of thermospheric wind that are not shown in the global models.

Calculation of dynamic and thermal processes parameters during the severe magnetic storm of August 5–6, 2011 (Kp max=8−) are presented. The magnetic storm was accompanied by negative ionospheric disturbance over Kharkiv which caused a number of changes in ionosphere. Plasma heating was observed during electron concentration depression in the F-layer which was accompanied by changes in neutral atmosphere composition and ionospheric dynamics.

The observation results of the effects in the geospace plasma during a partially (magnitude ∼0.42) solar eclipse are presented. The experimental data were obtained with an incoherent scatter radar of the Institute of the Ionosphere (near Kharkov). During the eclipse, the density at the F2 layer maximum decreased by 32%, the foF2 critical frequency decreased by 17.5%, and the altitude of the F2 layer maximum increased insignificantly. At altitudes of 290–680 km, the electron density decreased by ∼25%. During the eclipse, the electron and ion temperature decreased by 70–180 and 0–140 K, respectively, at altitudes of 190–490 km. Near the eclipse main phase, the plasma velocity vertical component decreased by 10–45 m/s at altitudes of 200–470 km, respectively. At the time of the eclipse main phase, the hydrogen ion fractional density increased by 50% as compared to the reference day at altitudes of 450–650 km.

The observations of the effects of the partial (about 77%) solar eclipse (SE) of March 29, 2006, in the ionospheric plasma are presented. The experimental data were obtained using the Kharkov incoherent scatter radar. At the moment of the maximum phase of SE, a decrease in the critical frequency of the ionospheric F2 layer by 18%, a depletion of the density in the F2 layer maximum by 33%, and an increase in the maximum height zm by 30 km were observed. The solar eclipse caused a decrease in the electron and ion temperatures by 150–300 and 100–200 K, respectively, within the height range 210–490 km. An increase in the relative density of the hydrogen ions during the maximum phase of SE by 20–25% within the height range 900–1200 km is detected. Calculations of the parameters of dynamical processes and thermal regime of the ionospheric plasma during SE are performed.

The modeling results of the zonal electric field and the vertical component of the plasma transfer velocity due to electromagnetic drift during August 5–6, 2011 and November 13–15, 2012 magnetic storms were presented. Confirmed that has a penetration of electric fields from magnetospheric origin in the mid-latitude ionosphere during strong geomagnetic disturbances. For the considered disturbed periods the neutral wind parameters were calculated using Kharkiv incoherent scatter radar data.