Wave disturbances in the ionosphere during a lasting solar activity minimum

Using the Kharkov incoherent scatter radar, observations of wave disturbances in electron concentration N in the ionosphere at heights of 120–600 km are conducted. The measurements were carried out in the periods of the spring and fall equinoxes and winter and summer solstices. The height-time dependences of the absolute ΔN and relative ΔN/N amplitudes of wave disturbances, as well as their spectral composition, were analyzed. It is shown that wave disturbances in the ionosphere with periods of 10–180 min were present at almost any time of the day and in all seasons. Their absolute and relative amplitudes varied from 6 × 10⁹ to 6 × 10¹⁰ m⁻³ and from 0.01 to 0.5, respectively. The maximum values of ΔN and ΔN/N were observed at a height of ∼200 km. The passage of the solar terminator changed substantially the wave disturbance parameters.     

Variations in the amplitude and phase of VLF radiowaves in the ionosphere during the August 1, 2008, solar eclipse

Time variations in the amplitude and phase of signals of the Russian telecommunication station (the frequency is 25 kHz) on the Arkhangelsk—Kharkov path with a length of about 1600 km on the day of the August 1, 2008 solar eclipse (SE) and on the adjacent days are analyzed. Two types of effects are detected. An increase of the signal amplitude by approximately 32% in comparison with the background days and the 2.1 μs time shift of the signal during 2—2.5 h is referred to the first type. Changes in the spectral composition of the quasiperiodic disturbances in the ionosphere presented the second type of the effects. For spectral analysis of the quasiperiodic variations in the amplitude and phase of the radio signal, the window Fourier transform, adaptive Fourier transform, and wavelet transformation were applied simultaneously. In the period of SE and after it, oscillations with periods of 10—15 min (according to the amplitude data) and also about 10 and 18 min (according to the phase data) were intensified. Based on radio signal characteristics, the parameters of ionospheric disturbances are estimated.     

Physical Effects of the Lipetsk Meteoroid: 2

Kinematics and Physics of Celestial Bodies - Abstract—Comprehensive modeling studies of the processes induced in all geospheres by the passage and explosion of the meteoroid near the city of...     

Oscillations of the geomagnetic field caused by the flight of Vitim bolide on September 24, 2002

The results of observation and analysis of oscillations of the geomagnetic field within the 1–1000 s range that followed the flight of a bolide with a mass of 50 t, diameter of about 3 m, and initial kinetic energy of 1013 J at a distance of 4850 km are given. Spectral analysis of the time variations of the geomagnetic field oscillation level was performed using three integral transformations. Four groups of disturbances to which the transport velocities of 7–8 km/s, 800–850, 300–400, and 260–280 m/s corresponded were detected and identified. The enumerated velocities are close to the velocities observed in geomagnetic pulsations after rocket launchings from the Plesetsk and Baikonur rocket sites. The magnetometer data were confirmed by the results of analysis of the recordings at a microbarograph located at a distance from the flight trajectory of the bolide of 4350 km.     

Possible Generation of Quasi-Periodic Magnetic Precursors of Earthquakes

Geomagnetism and Aeronomy - A mechanism for the generation of quasi-periodic magnetic precursors of earthquakes is proposed on the basis of air heating above an impending earthquake, the rise of...     

Dynamics of Convective Upwelling of Large-Scale Weakly Heated Atmospheric Aggregates

Izvestiya, Atmospheric and Oceanic Physics - Equations for the center-of-mass speed of the parcel of heated air, the mass of the entrained cool air, and the resulting buoyancy of the entire air...     

Atmosphere–ionosphere response to solar eclipse over Kharkiv on March 20, 2015

The results of the observations of aperiodic and quasi-periodic disturbances in E and F1 ionospheric layers and air temperature variations in the surface atmosphere on the day of the solar eclipse and control days are presented. The ionospheric processes were monitored by vertical sounding Doppler radar. The measurements showed that, near the time of the maximum coverage of the solar disk, the greatest decrease in the density of electrons in the layers E and F1 was ～27%, which is close to the calculated value (25%). The solar eclipse was accompanied by the generation of traveling ionospheric disturbances with a period of 8–12 min and a relative amplitude of electron density variations of ～0.6–1.5%. Because of the haze in the surface atmosphere, its temperature, which was monitored at observation points at a distance of 50–60 km from each other did not exceed 1°C near the time of the maximum eclipse magnitude.     

Partial solar eclipse of January 4, 2011 above Kharkiv: Observation and simulations results

Incoherent scatter radar observation results of the geospace response to the partial solar eclipse (SE) of January 4, 2011 (magnitude 0.78) above Kharkiv are described. The response to the SE was observed in variations in the electron concentration, electron and ion temperatures, and the vertical component of the plasma motion velocity in a wide altitude range (190–420 km). Parameters of thermal and dynamic processes in the ionosphere are theoretically calculated for the SE. It is shown that the SE resulted in significant changes in the dynamic and thermal conditions in geospace. The results show good agreement with results of an analysis of the geospace plasma responses to SEs occurring above Kharkiv in 1999–2008.     

Magnetospheric and Ionospheric Effects Accompanying the Strongest Technogenic Catastrophe

The results of observations of quasi-periodic variations of horizontal components of the geomagnetic field, the Doppler frequency shift of the radio waves reflected from the ionosphere, and observations of anomalous traces in ionograms during a catastrophe at the largest European ammunition depot on March 23, 2017, are presented. It is shown that the catastrophe was accompanied by oscillations of the geomagnetic field level (with periods from 5–6 to 13–14 min and an amplitude of 2–3 nT) and the ionospheric electron density (with periods from 14–16 to 50–60 min and a relative amplitude of ～1–10%). A mechanism for the transfer of disturbances from the catastrophe site to the ionosphere altitudes is proposed. A key role in this mechanism is played by the acoustic gravity waves generated by widespread explosions and large-scale fire events.