The purpose of this study is to estimate the energetics of the salient physical processes, starting at the onset of the solar storm of May 8, 2024, and ending with a disturbance of the Earth's lithosphere on May 10-12, 2024. Based on the raw data on the parameters of the solar storm, solar wind, and the auroras observations, the energetics of the salient physical processes that acted in the Sun-interplane tary-medium-magnetosphere-ionosphere-atmosphere-solid-Earth system in the aftermath of the solar storm of May 8-11, 2024, has been estimated. The power and energy has been calculated for solar flares, solar cosmic rays, dynamic, magnetic, and thermal solar wind pressures, for ionospheric, atmospheric, and lithospheric storms, as well as for disturbances in the geomagnetic and electric fields, auroras, infrasound, and the earthquake. The possibility of triggering energy release mechanisms in the Earth (lithosphere)-atmosphere-iono sphere-magnetosphere system has been validated. For the first time, classification scales for the main physical processes in the Sun- interplanetary-medium-magnetosphere-ionosphere-atmosphere-Earth (lithosphere) system have been developed and improved. According to all indices, the storm of May 10-11, 2024, is classified as severe or extreme. The main parameters of the storm have been compared with the parameters of a super unique storm analogous to the Carrington event, which show that the storm of May 10-11, 2024, was several orders of magnitude inferior in its parameters to the super unique storm. At the same time, the storm of May 2024 was significantly stronger than the storm of April 23-24, 2023. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Longitudinal, latitudinal, and altitudinal features of the zonal wind in the Northern Hemisphere under the influence of 27-day variations of solar activity (SA) were studied. The research aims to improve the accuracy of weather forecasts and deepening our knowledge about dynamic processes of the interaction of atmospheric layers. Zonal wind data by 5° latitude from the website https://psn.noaa.gov at the longitudes of Europe and North America from 15 altitude levels (from 1000 to 10 hPa) and SA data from the website https://www-app3.gfz-potsdam.de were used. Twenty high-amplitude 27-day SA cycles during the decline phase of the 23rd 11-year solar cycle from 2002 to 2004 were studied. The average 27-day wind changes for each latitude and altitude are calculated by the superposed epoch analysis separately for the winter and summer seasons. For the first time, 27-day latitudinal and altitudinal variations of zonal wind with an amplitude of 8 m/s, capable of influencing the weather in the extratropical atmosphere, were established. Despite the significant difference in the background wind field in winter and summer, the response of the wind field to SA influence is similar for both seasons. The maximum wind changes occur in the southern part of the polar atmospheric cell and the northern part of the Ferrell cell (50°–70° N) and gradually decrease in magnitude to the south and north. Wind changes are many times smaller in the tropical troposphere. At the boundaries of the global circulation cells, the direction of disturbed wind changes to the opposite. Changes in the position of jet streams by more than 1° in latitude and changes in the size of atmospheric circulation cells are also observed. In terms of height, the largest changes in the wind at all latitudes occur in the upper troposphere. There is a close relationship between the magnitude of the perturbed wind and changes in the tropopause height. The impact is realized through two-way dynamic stratospheric-tropospheric interaction, primarily in the area of the polar night jet and polar front jet stream. The presence of significant wind changes for the summer season indicates an important role not only of planetary-scale Rossby waves but also of shorter-wavelength waves. At the same time, their upward propagation can be ensured by nonlinear interaction between them.

Climatic conditions and the intensification of hostilities in the east of Ukraine in 2024 (August and September) led to the burning of large areas of forests and grasslands. A quantitative assessment of their consequences is necessary. Methods. System analysis, multifactorial analysis, mathematical modeling. Purpose. Calculation of the main parameters of fires in the ecosystems of Ukraine, which took place in the summer-autumn of 2024, and assessment of their ecological consequences. The results. The main energy parameters of forest and grass fires caused by the summer heat and military operations in Ukraine in 2024 were calculated. In late August - early September, virtually the entire east of Ukraine was burning. A total of about 43,000 hectares were engulfed in flames in Ukraine. About 500 kt of wood and 350 kt of grass burned. Emissions of smoke, soot, and nitrogen oxides exceeded the background values ​​of the masses of these substances many times over. The injection of polyaromatic hydrocarbons exceeded the background values ​​by 570, PM 2.5 microparticles by 14 times, and the power of acoustic radiation by 30 times. CO, SOx emissions did not exceed several tens of percent. The spread of fires in ecosystems, in addition to military operations, was facilitated by high air temperature, lack of rain and wind. Conclusions. Calculations and mathematical modeling showed that the consequences of the burning of forests and grasslands in Ukraine in 2024 were catastrophic. It is substantiated that most of the fires were caused by military actions on the territory of Ukraine. The ecological situation became significantly more complicated under the influence of a dust storm that came from Kazakhstan and Central Asia. The short-term and long-term environmental consequences are very significant.

Magnetic storm, ionospheric storm, atmospheric storm, and electrical storm are the components of a geospace storm resulting from a solar storm. In the literature, the main attention is paid to the analysis of severe and extreme geospace storms. It is these storms that have the greatest impact on the Earth–atmosphere–ionosphere–magnetosphere system. They are most dangerous for space-based and ground-based technological systems. Such storms have a significant impact on human well-being and health. Minor and moderate storms are much less studied than severe and extreme ones. There are good reasons to believe that such storms can have some impact on the systems and people. It is important that the frequency of occurrence of moderate storms is much greater than the frequency of occurrence of severe storms. All this determined the relevance of this work, which consists in the study of magnetic disturbances that arise during moderate geospace storms, which receive undeservedly little attention. The purpose of this paper is to analyze on a global scale the temporal variations of geomagnetic field components during moderate magnetic storms on April 28–29 and May 1–2, 2023. The latitudinal dependence of the geomagnetic field components temporal variations during two moderate magnetic storms in April–May 2023 and on reference days was analyzed on a global scale using the data of the global network of Intermagnet stations. The limits of fluctuations in the level of the geomagnetic field under quiet conditions and during moderate storms were estimated. The range of variations in the geomagnetic field level under quiet conditions decreased from 200–260 to 30–50 nT with decreasing geographic latitude. During the storms, these limits increased 1.3–2.1 times. The variations in the level of components at stations equidistant from the equator were close. This is true for both the Western and Eastern Hemispheres. The fluctuations of the geomagnetic field level at the stations operating approximately at the same latitude but in different hemispheres were also close.

The eruption of Hunga Tonga-Hunga Ha’apai volcano (briefly known as the Tonga volcano), which was the largest explosion recorded by modern instrumentation, attained a maximum on January 15, 2022. Only the Krakatoa eruption of August 26-27, 1883, could have rivaled the atmospheric disturbance produced. The initial volcanic plume rose to 58 kilometers, the greatest height ever reported. The Tonga volcano created a chain of effects in all subsystems of the Earth — atmosphere — ionosphere — magnetosphere system, which requires a more detailed analysis. The purpose of this paper is the statistical study of the main parameters of the wave generated in the air by the explosion of the Tonga super-volcano on January 15, 2022. The statistical study of the parameters of the explosive wave launched by the Tonga super-volcano has established the following. The time delay of the arrival of the wave increases with increasing distance between the volcano and the observatory taking measurements. The speed of propagation for the explosive wave remains virtually unalterable in the range of up to 136.5 Mm. Different techniques for estimating the speed yield the values of 313…315 m/s. At a particular distance between the volcano and the observatory taking measurements, the amplitude of the explosive wave is observed to fluctuate wildly (by a factor of 2 or greater), which is dependent on the orientation of the propagation path and on the state of tropospheric weather along the propagation path. The radiated wave front has been established to be well approximated by a cylindrical wave. This fact, together with the speed of propagation, suggests that the explosive wave made 4-fold travel around the Earth as a Lamb wave of the Earth’s atmosphere.

The frequency and intensity of forest fires is increasing year by year. It is due to global warming, which is associated with both natural and anthropogenic phenomena and processes There is another mechanism of global impact on the weather, abnormally high summer temperatures, severity and frequency of droughts, intensity and frequency of forest fires and their consequences. It is associated with the unique, cyclical, natural phenomenon of El Niño. The possibility of this phenomenon influence on the intensity of large-scale forest fires and their ecological consequences cannot be excluded, in accordance with the analysis of these processes and their quantitative assessment. There is reason to believe that the phenomenon may affect the intensity and frequency of forest fires in countries nearby. Such a country is, in particular, Chile, which experiences intense forest fires every year. Their intensity is compared to the intensity of record fires in Ukraine in 2020. Purpose. Comparative assessment of the ecological consequences of large-scale forest fires stimulated by natural and anthropogenic impacts (using the example of Ukraine and Chile in 2014–2024). Methods. Analytical review of the research problem, systems analysis of a number of accompanying processes, mathematical modeling and theoretical calculations. A methodology has been developed for assessing the ecological consequences of fires and burning of buildings in populated areas. Results. Areas of fires in 2017 and 2023 reached 0,5 million ha in Chile. Smoke ejections approached 10 Mt, which was one hundred thousand times higher than the norm. There were about 0,5 Gt of carbon dioxide ejections. They exceeded the background value in the fire areas by 200 times. The ejection of soot, carbon monoxide and hydrocarbons exceeded the norm by 120 thousand, 4 thousand and 160 times, respectively. Ejections of PM 2.5 microparticles and polyaromatic hydrocarbons exceeded the norm by 40 million and more than a million times, respectively. Ejections of nitrogen and sulfur oxides exceeded the norm by 3 thousand and 400–800 times, respectively. The combustion energy exceeded 2 thousand PJ, and the average combustion power exceeded 1 TW. The acoustic radiation energy, reaching 7 PJ, exceeded the background value by more than 1000 times. At the same time, the power of this radiation exceeded the norm by more than one hundred thousand times and was about 700 GW. Nitrogen ejections were the largest, reaching 1–10 Mt. The ejection of potassium, calcium, iron, zinc, chromium, and bromine was significant. The ejections of other chemical elements were significantly less. The construction of mathematical models made it possible to calculate the concentration and mass of harmful substances emitted during the burning of populated areas caused by forest fires. For the first time, it was established that ejections of substances during this can be significant. For the first time, the need to take into account the influence of micron smoke particles and polyaromatic hydrocarbons, which lead, respectively, to diseases of the respiratory tract, cardiovascular system and oncological diseases of residents of the entire country and beyond, was substantiated, and their mass and concentration have been calculated. Ejections of nitrogen and sulfur oxides, which stimulate the occurrence of acid rain, have been assessed. A comparative analysis of the characteristics and consequences of forest fires showed that they were more large-scale in Chile in 2017 and 2023 (almost 20 times) and in February 2024 than the record fires in Ukraine in 2020 in terms of their parameters and consequences. Conclusions. Mathematical modeling and calculations showed that the ecological consequences of large forests and buildings burning in Chile in 2023–2024 were catastrophic. They were accompanied by an intensification of the El Niño phenomenon. No less widespread were the ecological consequences of large-scale forest fires in Chile in 2017, caused by the hottest summer at that time. The size scale of fires in Chile and their consequences were many times higher than the corresponding parameters for the record fires in Ukraine in 2020.

A solar eclipse (SE) leads to perturbations of all subsystems in the Earth–atmosphere–ionosphere–magnetosphere system and to perturbations of geophysical fields. Each SE leads to a whole series of physical and chemical processes occurring in the ionosphere. Along with common features, each SE has its own peculiarities with regard to these processes. These processes depend on the solar activity phase, time of the year, time of the day, geographic coordinates, atmospheric weather, space weather, magnitude of eclipse, etc. Therefore, studying these effects during each SE is an urgent task. The aim of this study is to describe the results of the analysis of the effects features of the SE which was observed shortly after sunrise on October 25, 2022 mainly at high latitudes. The data obtained from a network of space stations and navigation satellites moving over the region of partial SE were used for observations. It is found that the maximum decrease in the total electron content (TEC) in the ionosphere in these observations was 1.6–4.1 TECU, and its relative decrease reached 12–25

We considered ionospheric effects of powerful seismic events using total electron content (TEC) maps of the ionosphere (http:// www.aiub.unibe.ch/download/CODE/) for the northern hemisphere, except the polar region, in the winter seasons of 2012— 2018. It is shown that the seismic-ionospheric effect is global, which is superimposed by local effects over the epicenters of individual earthquakes (EQ). Temporal TEC variations near the time of strong EQs at a great distance from their epicenters (global effect) consist of two maxima: the precursor and the «aftershock» maximum. In TEC variations over the EQ epicenter (local effect), only a precursor is usually registered, the amplitude of which at night (on average, ~ 8 %) is about twice as high as during the day. Always (locally and globally) after a positive surge in TEC, its reduced values are observed for several days. The maximum amplitude zone of the seismic-ionospheric effect belongs to the middle latitudes, especially 35...40° N, and within this zone at longitudes near 30° W (Mid-Atlantic ridge) and 140...150° E (Japanese islands and adjacent waters of the Pacific Ocean). Latitudinal amplitude maxima of the seismic-ionospheric effect are in good agreement with the latitudinal maxima of the EQ number in both geographic and geomagnetic coordinate systems. Changes in the EQ number and, consequently, the effect in the ionosphere on geomagnetic coordinates are more ordered, which indicates a significant impact on the seismicity of the same processes at the boundary of the liquid core and lower mantle, which form the Earth’s magnetic field. In addition to seismic belts and zones of mid-ocean ridges, an increase in TEC has been recorded along the so-called lineaments, marking the weakened zones of the Earth’s crust with increased flows of deep gases. The correspondence between the spatial features of seismicity and the seismic-ionospheric effect testifies in favor of the «radon» mechanism of lithosphere-ionosphere coupling and indirectly confirms the role of deep gases in the formation of seismicity planetary features.

The mechanism of electrical interaction between subsystems in the Earth–atmosphere–ionosphere–magnetosphere system is currently the least studied and substantiated subject. Moreover, some experts doubt its existence. This study is devoted to investigating the mechanisms of generation and propagation of electric fields that vary in time under the influence of transient high-energy sources of various physical nature and atmospheric turbulence enhanced by these sources, which is an urgent problem. Four options of penetration of electric fields from the atmospheric surface layer into the ionosphere have been proposed. Electrical parameters that depend on disturbances in the electric charge density and the characteristics of atmospheric turbulence have been estimated and numerically calculated for a number of high-energy sources. It is shown that the disturbances arising in the atmospheric surface layer are capable of penetrating into the ionosphere and even into the magnetosphere.

Subject and Purpose. At the beginning of the 21st century, a fundamentally new scientific direction was formed in radiophysics — fractal radiophysics. The subject of this review is the main practical ideas of "fractalization" in radio physics. The purpose of the work is a systematic presentation of the main results of the practical application of fractal theory in radiophysics, as well as a detailed analysis of the originality, novelty, and practical value of the obtained results. Methods and Methodology. The results of using the fractal approach in various fields of modern radiophysics are presented. The results of the application of fractal and multifractal analysis methods for various radiophysical objects, phenomena and processes are considered. The main features, advantages and disadvantages of this approach, as well as existing problems, are highlighted. Results. The main practical results of applying the fractal approach in radio physics are considered. The main features of solving the problem of radio wave propagation in fractal media are also discussed. The usage of fractals in applied electrodynamics is demonstrated by the example of fractal antennas, resonators, filters, capacitors, transistors, diplexers, frequency-selective surfaces and metamaterials, etc. Fractals in semiconductor and vacuum electronics are described by the example of the fractal structures of the cathode spot and the cathodes themselves, fractal electrodes and diffusers, as well as the avalanche breakdown of the p-n junction. The features of the application of fractal ideas in statistical and nonlinear radiophysics are considered. To illustrate the "fractalization" of physics and radiophysics of the geospace, the fractal processes that occur during earthquakes, in the atmosphere, ionosphere and magnetosphere, etc., are used. Conclusions. The main directions of practical application of the theory of fractals in modern radiophysics are analyzed, as well as the features of the new results obtained, which reflect one of the main properties of the surrounding world — its fractality, are discussed.

A solar eclipse (SE) can cause disturbances in all subsystems of the Earth–atmosphere–ionosphere–magnetosphere system, including the geomagnetic field. Using the data obtained at 15 stations of the INTERMAGNET network, the temporal variations of all components of the geomagnetic field are analyzed. It is found that the SE has been accompanied by a disturbance of the X-, Y-, and Z-components. The largest disturbances have been detected for the X-component (south–north). There has been a steady tendency to increase the disturbance of the X-component with an increase in the area of the solar disk obscuration. The disturbance magnitude of the X-component level under the influence of the SE is calculated. It is believed that the main mechanism for generating the magnetic effect is the disturbance of the ionospheric current system at the heights of the dynamo region. The results of observations and calculations are in good agreement with each other. In addition to a stable aperiodic effect lasting approximately 100…180 min, an increase in the range of fluctuations in the geomagnetic field level has been observed during the SE. This may indicate the generation of quasi-periodic disturbances of the geomagnetic field in the range of atmospheric gravity waves.

The theoretical and experimental study of the geomagnetic effect of cosmic bodies remains an urgent problem. This is especially true for meter-sized meteoroids, for which the very existence of the magnetic effect remains in question. The purpose of this article is to present the results of the analysis of temporal variations of the X-, Y-, and Z-components of the geomagnetic field detected by the International Real-time Magnetic Observatory Network (INTERMAGNET) on the day of the Kyiv meteoroid fall and on reference days. The analysis of temporal variations has shown that the levels of these components on the day of the cosmic body explosion and on reference days were significantly different. The level of X-component with a 6 min delay decreased by 2…5 nT, which lasted approximately 60 min. With a delay of 25 min and a duration of 25 min, a quasi-periodic disturbance was observed with a variable period within 4…12 min and an amplitude increasing from 0.3…0.4 to 1.2…1.5 nT. The first disturbance, which had a speed of approximately 300 m/s, could have been caused by a blast wave. The second disturbance was most likely associated with the generation and oblique propagation of an atmospheric gravity wave with a speed of hundreds of meters per second. Within the ionosphere, the disturbance propagated at a speed of approximately 660 km/s by means of magnetohydrodynamic waves. The temporal variations of the Y- and Z-components on the day of the explosion fluctuated for 60 min and decreased by 5…10 nT. The mechanism of long-lasting disturbances of these components remains unknown. It is likely that it could be related to the diamagnetic effect. There are reasons to believe that meter-sized cosmic bodies can cause the detected magnetic effect.

The explosion of the Tonga volcano on January 15, 2022, led to significant disturbances in the Earth (lithosphere, World Ocean) — atmosphere — ionosphere — magnetosphere system. The purpose of this paper is to present the results of a study of global variations in the geomagnetic field caused by the explosion of the Tonga volcano on January 15, 2022. To analyze the variations of the X-, Y-, and Z-components of the geomagnetic field, registrations at 12 stations of the worldwide INTERMAGNET network were used. When processing the time series, the trend calculated over 60 min with a step of 1 min was first subtracted, and then a system spectral analysis was applied. An analysis of the state of space weather made it possible to choose January 13 and 17, 2022, as reference days. An analysis of time variations in the level of all components of the geomagnetic field showed the following. On the day of the volcano explosion, approximately after 04:21, there were significant variations in the level of all components, but the largest variations were observed in the level of the Y-component. The shortest time delay was 6 min. At the same time, quasi-periodic variations of the geomagnetic field with a period of 4…4.5 min and an amplitude of ~2 nT were caused by acoustic resonance in the field of a standing acoustic wave generated by the explosion of the volcano. In addition, six groups of possible disturbances stimulated by the volcano explosion were found. It is important that in each group, the time delay of disturbances increased with increasing distance between the volcano and the station. It was found that the disturbances were transported at speeds close to 4, 1.5, 1 km/s and 500, 313, and 200 m/s. Such velocities are characteristic of slow MHD waves, a blast wave, an atmospheric gravity wave, a Lamb wave, and an ionospheric tsunami wave.

The capability of volcanoes to generate powerful explosive eruptions influencing the state of the ionosphere became known back in the 1980th. The Hunga-Tonga-Hunga-Ha’apai (Tonga for short) volcano explosion on January 15, 2022, has shown a surge of renewed interest in investigating effects in the Earth — atmosphere — ionosphere — magnetosphere system since this volcano can be rightfully classified as unique. A number of papers have already dealt with the ionospheric effects generated by the Tonga volcano. The temporal variations in the total electron content (TEC) were used to determine the number of volcano explosions to be five. The second and third explosions were the strongest, with the second being the most intense. The response of the ionosphere to the Tonga volcano explosion has been studied on local and global scales by making use of the Global Positioning System satellite constellation and measurements onboard the Swarm satellite network. In the vicinity of the volcano explosion, disturbances in TEC attained 5—10 TECU. In addition to the local effect, traveling ionospheric disturbances were observed to propagate, which were due to the generation and propagation of atmospheric gravity waves with speeds of 180 m/s to 1,050 m/s. Of particular importance to global-scale perturbations is the Lamb wave, which propagated with a speed of 315 m/s. At nighttime, plasma depletions of the equatorial ionosphere were revealed over the tropical Pacific Ocean when the electron density at 400—500 km altitude showed a decrease by 2-3 orders of magnitude. The length of these formations in longitude exceeded ~10 Mm, and they were observed for more than 4—5 h. The scientific objective of this study is further analysis of aperiodic and quasi-periodic perturbations in the ionosphere, which were caused by the Tonga volcano explosion, in a wide range of distances from the source of disturbance (from ~0.1 Mm to 5 Mm). To reveal the ionospheric response to the Tonga volcano explosion, the records of signals from Global Positioning System satellites have been analyzed. The intercomparison of temporal variations in TEC observed on the reference days and on the day when the volcano explosion occurred has resulted in the determination of basic principles of the generation of ionospheric perturbations and the estimation of numerical magnitudes of the parameters of the perturbations. Four groups of disturbances have been detected, each of which arrived at different time delays with respect to the moment of the volcano explosion. It is important to note that the time delay increases with increasing distance from the volcano to the observational instruments. The first group of speeds included the disturbances traveling with a speed close to 1,000 m/s and having an N-shaped profile. This perturbation was generated by a blast wave whose speed depended on the excess pressure and a priori exceeded the speed of sound. In the second group, the speed varied in the 336 m/s to 500 m/s range, within which the speeds of atmospheric gravity waves are found. The speeds in the third group exhibited variability within the 260—318 m/s limits, within which the Lamb wave propagates. The speed in the fourth group was estimated to be 190—220 m/s, which is a characteristic speed of the tsunami that was caused directly by the volcano explosion. The period of quasi-periodic perturbations varied from ~10 min to 20 min, while their amplitudes were from 0.5 TECU to 1 TECU. The observed ionospheric «hole» was proved to be produced by the volcano explosion directly, with the modules of the absolute and relative magnitudes of disturbances showing a tendency for decreasing with increasing distance from the explosion epicenter, from ~10 TECU to 2 TECU and from 37 % to 7 %, respectively. Contrary to the amplitude, the «hole» time delay and its duration exhibited an increase with distance from the volcano to the observational sensors, from 35 min to 100 min and from ~ 30—40 min to 120— 150 min, respectively. A mechanism for generating the ionospheric «hole» has been advanced, which is based on both the electric and non-electric processes (cracking, the friction of particles, condensation of water vapor, coagulation of water droplets, attachment of electrons, gravity segregation, etc.). The ionospheric «hole» is formed as a result of perturbing the global electric circuit, arising external electric currents, an increase in the electric field strengths by orders of magnitude in the atmosphere and the ionosphere, diffusion of the ionospheric plasma down to lower altitudes where the recombination processes become fast. The basic numerical characteristics have been established of the disturbances, whose fluctuations account for local time, the dusk terminator, sensor geographic locations, the location of subionospheric points on the satellite to receiver ray paths with respect to the equatorial anomaly, etc.

This study is aimed at comprehensively analyzing and estimating the effects in gas dynamics, as well as mechanical and optical effects, from the Kyiv meteoroid that entered the terrestrial atmosphere and exploded over Bila Tserkva raion, Kyiv oblast (Ukraine). According to the International Meteor Organization (IMO), the apparent magnitude of the meteoroid was –18. According to our estimates, the luminous power was 215 GW with an effective duration of 2.4 ± 0.2 s, the total luminous energy was 25.2 ± 2.5 GJ, and the initial kinetic energy was 0.09 ± 0.01 kt of TNT or 375 ± 35 GJ. The initial mass of the cosmic body was estimated to be 0.89 ± 0.09 t, the volume was 0.250 ± 0.025 m3, and the size was 79 ± 3 cm. The initial velocity of the meteoroid reached 29 km/s. The inclination angle, i.e., the angle that the trajectory makes with the horizontal plane, was 32°. The explosion altitude equal to 38 km and the inclination angle equal to 32° give an estimate of 3.5 t/m3 for the material density, which is close to the rock density. The energy of the processes, the gas dynamics effects, and the mechanical and optical effects from the celestial body have been analyzed. The main release of energy associated with the deceleration of the fragments of the celestial body, which was defragmented under a dynamical pressure of approximately 2.5 MPa, took place in the region with a length of 2 km at an altitude of approximately 38 km. A quasi-continuous defragmentation is suggested to produce a mass distribution that follows a power law. The main parameters of the ballistic and explosive shock waves have been estimated. For the Mach number of 97, the radius of the ballistic shock wave is estimated to be approximately 77 m, and the fundamental period to be 0.7 s, which showed a dispersive increase from 3.7 to 11.5 s with the propagation path length increasing from 50 to 5000 km. The radii of cylindrical and spherical wavefront shock waves were approximately 0.28 and 0.34 km, and their fundamental periods were approximately 2.6 and 3.2 s, respectively. These periods increased from 9.5 to 30.0 s and from 11.1 to 35.1 s with an increase in the propagation path length from 50 to 5000 km. In the vicinity of the meteoroid’s explosion height, the relative excess pressure was a maximum. It decreased with a decrease in the altitude and increased with an increase in the altitude up to approximately 120–150 km, at which it attained values of approximately 6–7

A large meteoroid entered the terrestrial atmosphere and exploded at an altitude of 26 km between the Kamchatka Peninsula and Alaska (geographic coordinates 56.9° N, 172.4° E) over the Bering Sea at 23:48:20 UT on December 18, 2018. The meteoroid has been named the Kamchatka (or Bering Sea) meteoroid. Its basic parameters are as follows: calculated total impact energy 173 kt of TNT, total optical radiated energy 1.3 × 1014 J, mass 1.41 kt, speed 32 km/s, size 9.4 m, and the trajectory directed at an angle of 68.6° with respect to the horizon. The entry of the Kamchatka meteoroid into the atmosphere was accompanied by the generation of a transient resonance electromagnetic signal in the 25–35 mHz band observable in the vicinity of the meteoroid explosion and in the magnetically conjugate region. Oscillations with amplitudes of 0.2–0.8 nT were observed over a 7-min interval. This study is aimed at analyzing the observations of the resonance electromagnetic effect from the Kamchatka meteoroid and discussing a mechanism for this effect. The resonance effect in the Earth’s magnetic field is analyzed using data with a time resolution of 1 s and an amplitude resolution of 1 nT from the database collected by the Intermagnet magnetometer network of magnetic observatories. The distance between the site of the meteoroid explosion and the magnetic observatories ranges from 1000 to 5000 km in the Northern Hemisphere and from 9010 to 12 425 km in the Southern Hemisphere. It is established that the only feasible mechanism is associated with the magnetic field displacement in the magnetosphere by the explosive impact of the celestial body, whereas only a negligibly small part of the meteoroid’s energy is spent on the generation of magnetic field perturbations. The meteoroid’s energy losses are similar to the losses in the reactive components of the radio frequency circuits, i.e., they return into the system. The oscillations cease after the meteoroid flies by, and the system returns into the initial state. The main results are summarized as follows. The resonance electromagnetic oscillations arose at 13 and 3 min prior to the Kamchatka meteoroid explosion. The duration of each observed perturbation is close to 7 min. The parameters of the quasi-periodic perturbations are similar to the parameters of magnetic Pc3 pulsations; however, they occured in the Y component of the magnetic field rather than in the X component of the magnetic field. Their observed periods are in the range of 33–36 s, and the amplitudes are in the range of 0.4–0.9 nT. Similar resonance oscillations were also recorded in the magnetically conjugate region. A mechanism for generating the resonance oscillations is proposed. The essence of the mechanism is that the meteoroid explosively impacts the magnetosphere and deforms the magnetic field lines that begin to oscillate at their eigenfrequencies. Depending on the McIlwain L-shell, the calculated period of oscillations is 19–169 s. For example, a period of 28–34 s is obtained with setting L ≈ 3–3.2, which is close to the observed period of 30 s. The generation of the resonance oscillations consumes approximately 10–4 parts of the meteoroid kinetic energy.

Subject and Purpose. The subject of this paper is to review the principal methods of fractal and multifractal analysis of signals and processes, in combination with a detailed consideration of the algorithms that can provide for a successful practical implementation of the methods described. Methods and Methodology. The results presented concern modeling of both deterministic and stochastic fractal and multifractal signals and processes. The corresponding practical methods of analysis are considered, with discussion of their essential features, advantages and disadvantages, as well as of the problems of application that may exist. Results. Several approaches have been discussed as to categorizing the signals and processes within the notion of fractality. A few tens of models of deterministic and stochastic fractal or multifractal signals and processes have been analyzed in detail. Over twenty methods of monofractal analysis have been analyzed, with identification of their features, advantages or disadvantages, and limits of applicability. The expediency of resorting to complex methods of monofractal analysis has also been discussed. Those methods are not based upon application of fractal analysis techniques alone but rather combine them with linear and nonlinear integral time-frequency transforms. The effectiveness of the ten most popular multifractal analysis techniques has been confirmed, with consideration of their special features, advantages and drawbacks. Conclusion. The mathematical foundations have been presented which underlie modern methods of analysis and modeling of fractal and multifractal signals and processes. The methods discussed may allow revealing a great amount of unique hidden information on the world around us.

The explosive Tonga volcano is among the unique ones. Its order of magnitude is the same as Krakatoa (1883), St. Helens (1980), El Chichón (1982), and Pinatubo (1991) volcanoes. The uniqueness of the Tonga volcano lies in the fact that the products of eruption of the Tonga volcano rose to a record height of 50–58 km, whereas the height of eruption of the most powerful Krakatoa volcano reached only 40–55 km. The Tonga volcano has estimates of 3.9 × 10 18 J for thermal energy, approximately 5.8 for volcanic explosive index VEI , approximately 5.5 for volcano magnitude M , and approximately 10.8 for eruption intensity I . We have estimated the explosion energy to be 16–18 Mt TNT. The problems of proving that a decrease in the total electron content (TEC), which was observed on January 15, 2022, in the ionosphere, was caused by the Tonga volcano explosion, and determining the principal parameters of the ionospheric hole are very urgent problems. This study is aimed at analyzing the parameters of the ionospheric hole created by the Tonga volcano explosion on January 15, 2022. Well-known GPS technologies are used to obtain data on time variations of the ionospheric TEC in the vertical column by measuring the pseudo-range and the integrated phase data at two frequencies along the path to each GPS satellite. The space weather conditions were favorable for observing the ionospheric effects caused by the explosion of the Tonga volcano. The calendar dates of January 13 and 17, which are used as reference days, were the least disturbed ones. The main results are as follows. It was found that the TEC on the reference days varied almost monotonically. Aperiodic and quasi-periodic variations of TEC were observed on the day of volcano eruption. Aperiodic variations are associated with a decrease in the TEC. This effect is called the ionospheric hole. It has been proven that the ionospheric hole is caused by a volcanic explosion. The delay time of the hole increases with an increase in the distance between the volcano and the observation site, while both the absolute value of the TEC and the relative value of its decrease are reduced. According to estimates, the horizontal size of the ionospheric hole did not exceed 10 Mm, and the time delay of its appearance did not exceed 122 min. The vertical speed of disturbance propagation was 36–72 m/s, and the horizontal speed was 2.2 km/s. The lifetime of the ionospheric hole was 120–200 min. The TEC in the ionospheric hole was reduced by approximately 2.5–10 TECU, which is a function of the distance from the volcano to the observation site, and the relative decrease ranged from –17 to –34%.

This study analyzes the variations in the levels of the Earth's magnetic field and its fluctuations in the range of periods of 1-1000 s that accompanied X-class solar flare on 6, 7, and 10 September 2017. Variations of the main Geomagnetic field (GMF) and the fluctuations in the range of periods 1-1000 s were measured by the magnetometer (located at 49.93(degrees)N, 36.95(degrees)E). The X9.3-class solar flare (SF) on 6 September 2017 induced substantial decreases in X-, Y-, and Z-component levels (-30 nT,-60 nT, and-15 nT, respectively), i.e., cro-chet effect. These reductions were restored within approximately 60, 150, and 5 min. Additionally, measurements from a magnetometer-fluxmeter (located at 49.64(degrees)N, 36.93(degrees)E) revealed a temporary sharp decrease in X-(approximately-3 nT) and Y-component (approx-imately-6 nT) fluctuations, followed by a subsequent increase/restoration lasting 12-15 min. The X8.2 solar flare that occurred on 10 September induced a minor reduction (<10 nT) in the levels of all local GMF components. Concurrently, it triggered a 1.5-to 2-fold amplification of quasi-sinusoidal oscillations in the Y-component fluctuations, characterized by a period of similar to 10-12 min and a duration of similar to 60 min. The study also discusses the mechanism of variations in the level of the GMF.(c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.

A solar eclipse (SE) causes recordable disturbances in all subsystems of the Earth–atmosphere–ionosphere–magnetosphere system and in geophysical fields. The response of the system to an SE substantially depends on the eclipse magnitude, the solar cycle phase, the atmospheric and space weather, the season, the time, and the observation coordinates. Manifestations of the response are also influenced by the observation technique. Despite the fact that the effect of a solar eclipse on the ionosphere has been studied for approximately 100 years, a number of unresolved issues remain. The purpose of this study is to describe the results of our analysis of temporal total electron content (TEC) variations caused by the annular solar eclipse on June 21, 2020, in the equatorial ionosphere. The authors analyzed 132 time dependences of the TEC that covered an extensive region with an eclipse. The maximum magnitude (Mmax = 0.9940) of the eclipse, which began at 06:39:59 UT, was observed in northern India in Uttarakhand and lasted 38 s. Space weather conditions on June 21, 2020, were favorable for studying the effects associated with the SE. To reveal the response of the ionosphere to the annular SE on June 21, 2020, the GPS signal recordings were processed. Time variations of the TEC in the ionosphere on reference days and on the SE day of June 21, 2020, were analyzed on a global scale. For this purpose, the results of measurements at twelve stations and eleven GPS satellites were used. The dependences of the absolute and relative TEC value decreases caused by the SE on a time of day are studied. The lowest value of the TEC decrease (–2…–3 TECU) was observed in the morning. In the daytime and in the evening hours, it reached –4…–6 TECU. The relative decrease in the TEC barely depended on a time of day and reached –30…–35