Abstract The calculation results and experimental data on the formation and development of a polarization jet in subauroral latitudes are compared. It is shown that the alternation of vertical and horizontal components of the ionospheric plasma–drift velocity leads to different variations in the main parameters of the F2 layer. An increase in the critical frequency of the F2 layer is revealed in certain

Abstract The Mg II core-to-wing ratio (c/w ratio) data is used to derive the solar extreme UV emission which brings a vital role in the creation of the Earth’s ionosphere region. A continuous Mg II c/w ratio data has scientific importance towards the analysis of the earth’s climate as well as for the solar chromosphere region. Various instruments of ESA and NASA satellites such as SUSIM, SOLSTICE,

Abstract The equatorial anomaly dynamics in the winter solstice is studied based on data from topside sounding of the ionosphere from the Interkosmos-19 satellite for high solar activity. This is the final study on the construction of the pattern of equatorial anomaly variations under conditions of high solar activity. Changes in the equatorial anomaly structure with local time and longitude are considered

Abstract Homogeneous series of solar cosmic-ray events for four solar-activity cycles against the background of decreased activity in cycles 23 and 24 are considered. The number of solar cosmic-ray events with energies above 10 MeV decreased insignificantly, while the number of ground-level enhancements in comparison between cycles 23 and 24 decreased by eight times. It is shown that the average contribution

Abstract Some authors suggest that space weather events may affect daily weather variables, such as air temperature and atmospheric pressure. Associations between space weather events and daily weather variables have been analyzed in four Baltic airports near Kaunas, Vilnius, Riga, and Tallinn during 2000–2016. We hypothesized that space weather events, 1–5 days before or after them, and intersection

Abstract A brief description of the multipath coherent radio technique installation is presented. Its goal is continuous monitoring of the dynamical processes in the ionosphere caused by space weather variations and the impact of high-energy sources in the Earth–atmosphere–ionosphere–magnetosphere system. The variations of radio-wave characteristics (the Doppler spectra and signal amplitudes) in the

Abstract On the basis of the results of theoretical studies of the manifestation of seismic activity it was shown that as a result of the impact on the atmosphere and the neutral component of the ionosphere of the acoustic pulse caused by a Rayleigh surface wave, both in ground-based experiments and in satellite observations at heights of the F-region of the ionosphere the perturbations of the vertical

Abstract A study of the wave changeability in the F2-layer critical frequency over Kaliningrad (54.6° N, 20° E) and Irkutsk (53° N, 103° E) stations during strong sudden stratospheric warmings is presented. Low solar activity was a common factor for all selected cases. The results of wavelet analysis of the time variations in foF2 showed that an amplification of the oscillations with periods of 4–10

Abstract The possible use of artificial neural networks—classical multilayer perceptrons—with coupling functions to forecast time series of the Dst geomagnetic index is studied. The basic forecast is based on parameters of the solar wind and interplanetary magnetic field measured at the libration point L1 in an experiment on the ACE spacecraft. It is shown that the largest contribution to the improvement

Abstract Numerical values of the criteria for the efficiency of the determination of the critical frequency of the F2 layer of ionosphere over European Russia are calculated with ionospheric models corrected based on vertical-incidence sounding data from an ionosonde. Two correction techniques are considered: the selection of an effective value of the input heliogeophysical index and linear-correlation

Abstract The paper presents the results of a study of the relationship of seismic events with geomagnetic disturbances arising from the acoustic impact on the lower ionosphere, which are caused by vibrations of the Earth’s surface at distances of several thousand kilometers from the earthquake source. The measurements were carried out at Mikhnevo Observatory, which is equipped with an instrumental

Abstract A significant proportion of publications related to the ionospheric disturbances that arise during earthquake preparation over the regions of their preparation refer to these disturbances as anomalies. In this case, the identification of the ionospheric precursor is actually based on an estimate of the amplitude of the deviation of the ionospheric parameters from the undisturbed value. We

Abstract The system for the preparation of quasi-definitivedata of the INTERMAGNET standard is described. Unlike the final data, which was prepared no earlier than 1 year after the measurement, the data provided with the described system are available 1 day after the last series of absolute observations. Quasi-definitivedata are used to model fast variations in the main magnetic field of the Earth

Abstract Under the assumption that the evolution of the total electron content (TEC) in a quiet ionosphere can be described within the framework of the linear dynamic-stochastic approach, the corresponding model is constructed and verified. The TEC data archive for 1998–2018 of the Crustal Dynamics Data Information System (CDDIS) of the National Aeronautics and Space (NASA) Administration was used

Abstract A new analytical model for the generation of axially symmetric jets (directed jets) in a nondissipative, nonequilibrium stratified plasma has been created in the magnetohydrodynamics approximation. The model is based on the assumption of Schwarzschild convective instability in plasma and on the condition that the magnetic field lines are frozen into matter. It is shown that jets with poloidal

Abstract Oscillations of coronal loops with electric currents from one base to another are studied. The energy of longitudinal currents can be a source of energy for loop flares (Alfvén and Carlqvist, 1967). A simplified model of a loop in the form of a composite cylindrical magnetic tube containing a shell with a potential azimuthal magnetic field is considered for the theoretical study of oscillations

Abstract The heliospheric modulation potential was reconstructed based on data from the North Greenland Ice Core Project (NGRIP) on the content of the cosmogenic isotope 10Be in the Greenland ice from the end of the 14th century CE. This time interval includes global solar-activity minima, such as the Spörer (≈1460–1550 CE), Maunder (≈1645–1715 CE), and Dalton (≈1790–1830 CE) minima. The reconstruction

Abstract The results of long-term mesoscale observations in the microwave range are reviewed. The rationale for the resumption of observations at the Havana Radio Astronomy Station is justified. Domestic observations at a wavelength of λ5 cm have a long observation interval and can effectively complement the global series of observations. A comparative analysis of the results of solar observation in

Abstract The directivity of transverse electromagnetic waves generated in a plasma at a double plasma frequency during the coalescence of plasma waves is calculated for various angular distributions of these waves. It is shown that the directivity of the generated electromagnetic waves is determined by the angular distribution of the spectral energy density of the Langmuir waves and is practically

Abstract The possibility that large-scale coronal loops of solar-type stars and M dwarfs make a significant contribution to the white-light continuum emission is considered. It is shown that that the existence of high-density (>1012 cm–3) coronal loops contradicts the standard model of solar and stellar flares. As a result, the optical flare emission cannot be determined by free–free or free–bound

Abstract The rotational effect observed in variations of areas of polar coronal holes with a period of 14 days is analyzed with SDO data by using Coronal Hole Identification with the Multithermal Emission Recognition Algorithm (CHIMERA) algorithm and the algorithm for the identification of solar structures from neural networks. A physical interpretation of the observed rotational effect associated

Abstract Solar-climatic correlations were examined over the timescales, corresponding to solar cycles of Schwabe, Hale and Gleissberg, during the last 3–4 centuries using eight proxy and direct indices of: (a) summer climate in Fennoscandia, (b) sea surface temperature in the North Atlantic and (c) solar activity. Using novel and improved data records new evidences of a link between solar activity

Abstract—The main subject of the study is an analysis of time series of the width of annual rings of spruce and pine (D) that were obtained during the implementation of a scientific project supported by the Institute of Astronomy of the Bulgarian Academy of Sciences and the Ministry of Agriculture and Food in 2012–2014. The project is a continuation of our previous study (Komitov and Kaftan, 2019)

Abstract Changes in the umbra brightness and in the magnetic field over time should occur on long-period sunspot oscillations in accordance with Birman’s idea of inhibition of circulation (overturning) convection by a strong vertical magnetic field in antiphase mode.When the sunspot as a whole shifts upward, its power flux tube expands with a fixed magnetic flux, the magnetic field decreases, and the

Abstract Calculated insolations of the Earth are analyzed. The main trends in the modern solar climate change are identified: increased latitudinal contrast and smoothed seasonal differences. The correlation of the meridional insolation gradient with the average annual energy transfer in the ocean–atmosphere system is revealed. The features of changes in the annual and semiannual meridional insolation

Abstract The paper presents a modified version of a previously published 3D model of the solar facular knot (Solov’ev and Kirichek, 2019), which successfully describes the main structural features of the solar facular formations. As in the main model, we use the solution (Schatzman, 1965) in the potential approximation as the basis of the magnetic structure of the facular element. The magnetic profile

Abstract The paper presents the results of processing of data on the soft X-ray solar radiation obtained by the PINGVIN-M instrument aboard the KORONAS-FOTON spacecraft in July 2009. The high sensitivity of the device, combined with effective compensation for the magnetospheric background over most of the orbit, made it possible to study in detail the evolution of X-ray radiation from the active region

Abstract Polar and low-latitude faculae were identified in daily images based on white-light observations from the MDI (1996–2011) and SOHO (2010–2019) space observatories. The boundaries of the faculae were combined with magnetic field observations at the closest possible instant of observation. The time and latitude distributions, as well as other properties of polar and low-latitude faculae, were

Abstract The properties of the solar constant variability are considered according to the results of satellite observations (http://lasp.colorado.edu/home/sorce/data/tsi-data/). The obtainment of satellite data with an accuracy of 0.01% that is devoid of atmospheric influence allows a detailed analysis of variations in this index of solar activity and space weather for solar-activity cycles 21–24.

Abstract The situation with the reliability of calculations of the magnetic field of the solar corona remains a topic of discussion. There is, in particular, the problem of significantly lower calculated values of the magnetic field than those recorded near the Earth. The authors propose an explanation in which the magnetic fields are underestimated due to the existence of magnetic sources at different

Abstract Two main features define a sunspot as an object: a strong magnetic field and a low umbra temperature. The same can be said about a facular knot, in the center of which there is a dark micropore, and the magnetic field is several hundred Gauss (which noticeably exceeds the level of equipartition of about 200–250 G), sometimes reaching 1000 or 1200 G. The temperature decrease in these activity

Abstract Data from observations of the photospheric magnetic field at a number of ground stations (STOP, WSO, GONG) and by the SDO/HMI satellite for 2014–2019 are examined in terms of the accuracy of the model calculations of the speed of calm solar wind and the areas of coronal holes obtained on their basis. A high positive correlation was found (R > 0.5) between the simulation results and satellite

Abstract Self-organization is a property of any nonlinear, dynamic, dissipative system that evolves under the influence of external forces and positive feedback. Self-organization leads to the creation of order from chaos, thus reducing the entropy of the system. As a result, numerous small elements and/or short-lived elements form structures with large spatiotemporal scales. One very important property

Abstract The spatial dynamics of microwave emission (data from the Nobeyama Radioheliograph) of active regions with a complex magnetic field configuration before powerful flares, as well as the fine structure of active sources of ultraviolet (UV) emission based on AIA/SDO data, are studied. It is shown that there is unsteady behavior of microwave sources, along with the ignition of a system of crossed

Abstract The possible application of temperature reconstructions based on measurement of the 40Ar concentration in ice layers of the Greenland ice sheet to study past solar activity with radiocarbon data is considered. The rate of 14С production and the heliosphere modulation potential from the 2nd millennium B.C. to the middle of the 18th century A.D. is reconstructed with allowance for the Earth’s

Abstract— A statistical study of long-duration (long-duration event, LDE) flares in the soft X-ray (SXR) range for solar cycles 23 and 24 is carried out. Graphs of the dependence of the strength of LDE flares and coronal mass ejections (CMEs) on the duration of these flares are constructed. As a result, we find that a significant proportion of LDE flares is not associated with large mass CMEs. This

Abstract Properties of solutions for parallel magnetohydrodynamic (MHD) shock waves in collisionless plasma with heat fluxes obtained in the 8-moment MHD approximation are discussed. The domain of upstream shock-wave plasma parameters in which there are solutions that preserve physical meaning of the downstream plasma parameters is determined. New results have also been obtained for the heat fluxes

Abstract The method of path integrals is used to average the magnetic-induction equation written for the vector potential over the velocity field. This approach avoids the assumption that the random field is two-scale, replacing it with the assumption of short time correlations. As a result of averaging, the classical equation of the mean field is obtained, at least for a homogeneous and isotropic

Abstract Various aspects of the of geoefficiency of solar-activity phenomena, such as flares and coronal mass ejections (CMEs), are considered. The number of geoefficient events was about two times lower in the 24th cycle than in the 23rd cycle. Statistical data on major flares and the Dst index in different phases of the 24th cycle is compared. Large flares (X-ray class > M5) were analyzed based on

Abstract The article considers 30 solar flare events during which the spectra of solar cosmic-ray (SCR) protons with energies above ~80 MeV were recorded in the course of the PAMELA experiment (July 2006–September 2014) and those with energies above ~0.4 GeV recorded during the AMS-02 experiments (June 2011–September 2014). The Konus-Wind data are analyzed for the same time period (2006–2014), during

Abstract— The data on the content of the 14C cosmogenic isotope in the natural archives make it possible to study the solar activity (SA) in the past centuries and millennia. However, the 14C content in the natural archives is influenced not only by the intensity of incoming galactic cosmic rays (GCRs), which are modulated by the interplanetary magnetic field and vary according to SA variations; changes

Abstract A source of high-frequency electromagnetic radiation is formed by energetic particles in the magnetic structures of plasma corona. Energetic particles are formed in the electric and magnetic fields of the dissipative structures of the magnetic reconnection caused by the low-frequency induction process in a hot, collisionless plasma expanding over the magnetization regions. The stationary process

Abstract Analysis of the phenomenon of the shrinkage of a coronal magnetic loop during the impulsive phase of a flare makes it possible to determine both the evolution of electric current in the loop and the loop resistance. We show that the flare process is accompanied by a substantial (two orders of magnitude) increase in the loop resistance along with a slight (~20%) decrease in the electric current

Abstract— Quite often powerful flares occur during a decrease of solar activity. In this work, we make an attempt to consider X-class flares at the minima of solar activity cycles as a separate group of events. Out of nine X-class flares we selected three such events that occurred at the minima of solar cycles 22–24: SOL1996-07-09T-09:09 (X2.6), SOL2006-12-13T-10:26 (X3.4), and SOL2017-09-06T-11:53

Abstract According to data on earthquakes with a magnitude of М ≥ 4.5 recorded on the planet in 1973–2017, a UT variation in the number of earthquakes with an amplitude of ~10% was found and compared with the UT variation in the atmosphere gradient of electric-potential (Carnegie curve), the amplitude of which is ~20%. It is shown that the amplitude of UT variations in the number of deep-focus earthquakes

Abstract The variations in the parameters of twice ionized helium ions He++ of solar wind plasma during the passage of the front of the interplanetary shock are studied. Data taken from measurements by the Bright Monitor of Solar Wind (BMSW) installed onboard SPEKTR-R satellite were used to calculate the parameters of the He++ ions: the speed, temperature, and absolute and relative density (helium

Abstract Cosmic rays are the main factor in atmospheric ionization; they affect the formation of clouds and determine the properties of the global electrical circuit. The mechanisms of atmospheric processes involving cosmic rays are very complex and are far from understanding. Their research requires experimental installations distributed around the world. In this context a cosmophysical complex consisting

Abstract In this paper, 2046 active regions of solar cycle 23 and 1507 active regions of solar cycle 24 observed during the period from May 1996 to December 2018 have been studied. The sunspot groups are distributed according to the recently proposed magneto-morphological classification. Regular active regions (obeing Hale’s polarity law, Joy’s law, and having a leading sunspot that prevails over the

Abstract The luminescence intensity profiles of Lyman–Birge–Hopfield bands of molecular nitrogen have been calculated for the precipitation into the Earth’s atmosphere of electrons with energies of 10 keV to 10 MeV. With an increase in the energy of electrons penetrating the atmosphere, there is an increase in the contribution of the quenching of the a1Πg N2 state in molecular collisions. This leads

Abstract The influence of geomagnetic activity on slips of navigation signals of the global positioning system (GPS), as well as an increase in the amplitude of jumps in the total electron content at high latitudes, has been studied in detail. It is shown that the navigation signal of the L2 frequency is subject to more frequent malfunctions than the L1 frequencies, both in calm conditions and during

Abstract The differences in the dynamics of the asymmetrical part of the geomagnetic disturbance at middle and low latitudes during magnetic storms initiated by different interplanetary sources are analyzed. The analysis is performed with the SYM-H, ASY-H, and Dst indices from the OMNI database during the periods of 58 intense magnetic storms with –270 ≤ Dstmin ≤ –90 nT that were recorded in 1995–2017

Abstract The consistent inclusion of global electric circuit sources of ionospheric and magnetospheric origin in distributed numerical models of the circuit is discussed. It is shown that the most natural approach to this inclusion is to introduce into the boundary conditions at the outer boundary of the model atmosphere the corresponding perturbation of the potential specified up to an unknown constant

Abstract The paper presents the results of the reconstruction of the effective height h' and the slope of the profile β of the electron concentration in the D layer of the ionosphere during X-ray flares of M- and X-classes at the midlatitudes. The reconstruction was carried out with data from measurements at the observatory of the Institute of Geospheres Dynamics of the Russian Academy of Sciences

Abstract Regularities in the distribution of extreme (burst) increases in paleointensities from 3000 Ma to the present have been studied. Paleointensity bursts that exceed several times its average values Havg have been found to occur over the entire geomagnetic history. The data obtained from thermomagnetized rocks have made it possible to identify variations with characteristic times of 200 Ma in

Abstract The potential to diagnose the beginning of the solar cycle based on the detection of small-scale magnetic formations, the magnetic nodes of ephemeral active regions in the zone of mid-heliolatitudes from 40° to 60°, has been studied. Magnetic nodes were detected at the stage of their emergence by the multifractal segmentation method, which was previously used to fix new magnetic fluxes of

Abstract— Stable auroral red (SAR) arcs are the result of the interaction of energetic ring current ions with the outer plasmasphere (plasmapause). The article analyzes the results of the observation of a SAR arc by an all-sky imager at Maimaga station (58° CGMLat, 202° CGMLon) with the simultaneous detection of the plasmapause and energetic ion fluxes by the Van Allen Probe B (VAP-B) satellite at

Abstract Two proton events (>100 MeV; GOES, ACS SPI) associated with weak flares (C1.2, GOES class) in the soft X-ray range that occurred on November 26, 2011, and September 29, 2013, are analyzed. These events were accompanied by significant fluxes of relativistic electrons (>1 MeV; SOHO EPHIN) in the interplanetary space. The time profiles of these protons and electron fluxes were similar during

Abstract The ion pressure in the regions of ionospheric projections of the plasma mantle, polar cusp, low-latitude boundary layer, and the region of structured precipitation of the auroral oval during magnetic calm is studied based on data from the DMSP F6 and F7 low-altitude spacecraft. It is shown that the level of ion pressure in all of these regions does not depend on either the polarity or the

Abstract— The results of a comparative analysis of the fluxes and spectra of solar protons measured in September 2017 by satellites at different orbits (ELECTRO-L No. 2, GOES 13, and METEOR-3 No. 2) and the results of modeling of the ionization rate in the polar atmosphere based on data from these experiments are presented. It is found based on data from Russian and US satellites that the proton spectra

Abstract— In this present paper, the nonlinear time series techniques were used to analyse solar quiet variation in the horizontal component of the geomagnetic field (SqH) data collected from the INTERMAGNET during the year 2012. The complexity of the nonlinear dynamics based on estimated time delay (τ) and embedding dimension (m) are expressed by Lyapunov exponents (LE). The positive values of the