Vol 88, No 3 (2024)

We studied geomagnetic pulsations with periods of about several minutes and geomagnetically induced currents related to them. The interrelation is studied between efficiency of pulsations in currents’ generation and parameters of interplanetary magnetic field and plasma of the solar wind at different delays. Geomagnetic data and the recordings of geomagnetically induced currents in the Russian North and Finland are used for the analysis. It is shown that efficiency of current generation by pulsations grows if the solar wind velocity is not lower than 500 km/s for several hours.

Using the Global Self-Consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP), we previously gave an interpretation of the ionospheric effects of the March 2015 geomagnetic storm, identified and analyzed the positive aftereffects. Further analysis of the numerical simulation results showed that the positive aftereffects manifest themselves differently in different longitudinal sectors. This paper presents the results of studying the dependence of disturbances in the parameters of the upper atmosphere on the time of the onset of a geomagnetic storm in UT. For this, additional calculations of geomagnetic storms were carried out, identical to the considered storm in March 2015, which began on March 17 at 12 UT, with a start time of the geomagnetic storm shifted by 00, 06, and 18 UT. It is shown that for the family of storms under consideration, the effects of the thermosphere wind are significant in the formation of N_mF2 disturbances in the main phase of the storm. The mechanism for the formation of ionospheric aftereffects in the form of positive N_mF2 disturbances are n(O)/n(N₂) disturbances at heights F of the ionospheric region.

A Pulsating Aurora Imaging Photometers System (PAIPS) is being created using observatories of the Polar Geophysical Institute on the Kola Peninsula to study the structure of pulsating auroras (PsA) in the near ultraviolet range (300—400 nm). We presented a description of two PsA cases measured by the PAIPS system together with all-sky cameras. For the first one, a frequency analysis of the signal is given and it is shown that for an hour and a half, pulsations occur at a quasi-constant frequency of about 1 Hz. For the second one, measurements of the intensity ratio in the 337 and 391 nm wavelengths are presented. An analysis of simultaneous observations of optical cameras in the field of view of the spectrometer shows that the emission in the “on” phase is “greener”, i.e., corresponds to less energetic precipitating electrons. Stereometric observations with a camera in observatory Lovozero gives the maximum correlation coefficient for the time series of cameras at altitudes of 145—150 km and ~92 km.

A numerical model has been developed to calculate the electromagnetic response in the ionosphere from grounded ultra-low-frequency transmitters of finite length L. Such megatransmitters are the ZEVS installation with a carrier frequency of 82 Hz and the FENICS installation, which can generate artificial emissions at frequencies from fractions of a Hz to a few hundreds of Hz. The amplitude of radiation excited in the upper ionosphere by a grounded horizontal current suspended above a high-resistance earth’s surface has been calculated. The altitude profile of the plasma parameters was reconstructed using the IRI ionospheric model. For the ZEVS transmitter (L = 60 km) powered by a current of 200 A, the simulated amplitudes of the electromagnetic response in the nighttime ionosphere can reach ~60 μV/m, which was confirmed by observations on the DEMETER satellite. According to calculations, the FENICS facility (L = 100 km), powered by a current of 100 A, can generate radiation in the nighttime upper ionosphere with a frequency of 10—100 Hz and an amplitude of up to ~60—70 μV/m. The FENICS facility can be used to excite artificial Pc1 pulsations that could be detected on low-Earth-orbit satellites (e.g., CSES). To create pulsations in the nighttime ionosphere at a frequency of 0.5 Hz with the amplitudes of the magnetic component >1 pT and the electric component >10 μV/m, the current in the FENICS antenna is to be >100 A.

We presented the results of the analysis of VLF signals of the RSDN-20 radio navigation system recorded at Lovozero, Verkhnetulomsky (both on the Kola Peninsula) and Barentsburg (Svalbard Archipelago) observatories. We found events of an unusual decrease in the amplitude of the horizontal magnetic field at night ionospheric conditions, which occurred during substorms with the AL index below –500 nT. The cases, when optical observations were available during the substorm according to which auroral precipitation were registered, are considered. The observed effect is probably associated with local fluctuations in the electron density profile of the lower ionosphere caused by auroral precipitations during a substorm.

The growth of scintillations of GLONASS and GPS satellite signals using the Septentrio GNSS receiver installed in the city of Apatity during a strong magnetic storm on March 23—24, 2023, is analyzed. According to the ionosonde data at the Lovozero station and the data of the EISCAT radar in Tromsø, it was shown that the growth of phase scintillations is caused by an increase in the plasma concentration mainly in the E-layer of the ionosphere. The growth of phase scintillations is accompanied by the appearance of discrete forms of auroras.

The results of a study of the internal small-scale structure of a polarization jet/SAID using high-frequency data from various satellites are presented. The minimum size of irregularities and the typical internal composition of a stratified subauroral ion drift (SSAID) are confirmed. A two-peak structure has been found, which represents two large strata of the polarization jet/SAID. The shift of strata of electron density and temperature in latitude relative to each other is shown.

Analysis of fluctuations of the satellite radio-signals scattered on small-scale irregularities in F-region of the ionosphere and obtained recorded by a terrestrial ground-based receiver in Moscow showed has shown that often two or three maxima are present in the latitudinal profile of amplitude dispersion variance. The orientation of the cross-field transverse or transversal anisotropy of the irregularities was determined and compared with the drift direction obtained by the ionosonde DPS-4 using the LocalDrift program.

The intensities of the Atmospheric bands of molecular oxygen I_vʹvʺ (cm^–2s^–1) in the nightglow of the Earth’s atmosphere are calculated for different latitudes and seasons. The calculations were performed using experimental data on the profiles of atomic oxygen concentrations for different seasons. The calculated integral intensities of Atmospheric bands are compared with experimental data obtained from the space shuttle (STS transport system), as well as from the Keck I telescope. It is shown that there is good agreement between theoretical calculations and experimental data for the considered latitudes, but better agreement is received with data obtained from Keck I telescope.

A numerical simulation of atmospheric wave propagation ahead of a strong pressure spike during a squall in Moscow on May 29, 2017, was performed using a three-dimensional version of the high-resolution nonlinear numerical model AtmoSym. The meteorological source was specified based on experimental observations of a network of 4 microbarographs located in the Moscow region. Wave perturbations in the upper atmosphere caused by the generation of internal gravity waves by the meteorological source were estimated.

We simulated the galactic cosmic rays’ particles propagation in the Earth’s magnetosphere, given by the IGRF and CHAOS magnetic field models, while the second of them additionally has a lithospheric field component that is absent in the first model. The power spectra of the flux of galactic cosmic rays at a fixed height above the Earth’s surface are obtained and their difference is found for large orders of the multipole expansion, l > 7. For l > 20, the result can be explained by the contribution of the lithospheric component of the magnetic field in the CHAOS model compared to IGRF, and for l > 20, the difference in the accuracy of the description of the main field, since IGRF is limited to the 13th order of expansion.

We presented a balloon experiment EUSO-SPB2 for the study of ultrahigh and extremely high energy cosmic rays. The main characteristics of the fluorescent and Cherenkov telescopes and their scientific tasks are given. As part of the pre-flight preparation, the calibration of a multi-channel photodetector was carried out.

A new calculation of the prompt component of atmospheric leptons — muon neutrinos and muons from the decays of charmed particles is performed for the same hadron cascade model that was used in calculating the characteristics of atmospheric leptons from the decays of π- and K-mesons. Spectral zenith-angular distributions of prompt and (π, K)-leptons are obtained. The cross-energy intervals are found for which the prompt lepton fluxes contribution comparably to the fluxes of (π, K)-muons and neutrinos. The possibility is shown of the prompt neutrinos detecting at energies much lower of the cross-energy.