As Akasofu noted, no two geomagnetic storms are identical, yet the storm that occurred between 12 and 14 November 2025 stands out as an exceptional phenomenon. Its impact was evident across multiple layers of the ionosphere and numerous parameters, making it essential to conduct a comprehensive multi-parameter analysis of this event. Such an analysis relied upon data from the four LAERT topside sounders mounted aboard the recently launched Ionosfera-M satellites. Global ionospheric dynamics were thoroughlyexamined during the storm period, particularly focusing on the polar and auroral zones, along with the equatorial anomaly region. Notable features included sharp electron density gradients, widespread F-layer disturbances, and the formation of giant plasma bubbles. These elements collectively contributed to the dynamic picture of the ionospheric storm captured through multi-parameter measurements by the LAERT sounders.

The Sun's significant effect on climate is its indirect effect on the flux of galactic cosmic rays (CR) into the atmosphere. This study examines the specific changes in the CR intensity (specifically its decrease - Forbush decrease) and solar and geomagnetic parameters during the formation and intensification of hurricanes over the North Atlantic Ocean. Thirteen non-overlapping strong hurricanes (category 4 and 5) during the 24th solar cycle were analyzed. Results indicate that alterations in solar activity and CR intensity tend to precede the appearance and intensification of the most powerful North Atlantic hurricanes. The minimum in CR occurs on average 7 days before the peak intensity of the hurricane. The maximum in sunspot number is observed 17 days prior to the hurricane's peak intensity, i.e., 10 days before the CR minimum. Analysis of vertical temperature profiles in the hurricane propagation region suggests the interrelation between temperature variations at the tropopause level and variations in the level of atmospheric ionization by CR. The reduction of the ionization source associated with fluctuations in cosmic rays is suggested to be correlated with a decrease in latent heat release at the tropopause level, which may contribute to a lowering of air temperature, an increased vertical temperature gradient, and enhanced convection.

Although satellite sounding of the upper ionosphere yielded impressive results and enabled numerous important discoveries across different nations, its application halted in 1999 following the deployment of the last topside sounder aboard the Russian space station Mir. During the last decades monitoring of the upper ionosphere traditionally relied on total electron content (TEC) measurements obtained from ground-and space-based Global Navigation Satellite Systems (GNSS) receivers. However, this methodology struggles to resolve the internal structure of the ionosphere effectively, particularly in scenarios involving steep horizontal gradients of plasma density. Alternative techniques, such as GNSS occultation experiments, although widely adopted, suffer from similar limitations when confronted with strong gradient conditions. Meanwhile, ground-based tomographic imaging, dependent on empirical models like IRI and NeQuick, fails to reconstruct sharply layered ionospheric structures reliably. Addressing these gaps, the pioneering launch of two LAERT topside sounders on November 5, 2024, aboard the Ionosfera-M1 and Ionosfera-M2 satellites marked a turning point to direct ionospheric sensing after a hiatus of 25 years. Deployed into a sun-synchronous orbit at an altitude of 820 km, the new-generation LAERT sounders introduced multifunctionality, combining traditional vertical sounding with advanced techniques such as HF radio spectrometry and relaxation sounding. Retaining the capability to deliver precise vertical profiles of plasma density, these innovations allow for a more nuanced exploration of plasma dynamics near the spacecraft, magnetospheric interactions, and extraterrestrial phenomena like solar radio bursts. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Geomagnetic storms drive complex ionospheric responses through coupled electrodynamic and thermospheric processes, yet attributing storm-time TEC perturbations to specific mechanisms remains challenging. We investigate the ionospheric response to the 12-13 November 2025 intense geomagnetic storm (Dst minimum = -214 nT) in the 60-180E sector using a coordinated multi-instrument data set comprising JPL GIM TEC, dense regional GNSS networks, continuous BeiDou GEO links, COSMIC-2 radio occultation, ground ionosondes, Swarm in situ electron density, HF Doppler soundings, and TIMED/GUVI thermospheric composition observations. The observations reveal a dayside-dominant positive TEC storm with pronounced hemispheric asymmetry, where Northern Hemisphere mid-to-low latitudes exhibit stronger and longer-lasting enhancement than the Southern Hemisphere. Joint analysis of radio occultation, ionosonde, and Swarm data indicates that the enhancement is density-dominated with NmF2 and foF2 increases but with no coherent, sector-scale peak-height uplift in hmF2 or hF2, posing challenges for uplift-only electrodynamic interpretations. Coherent large-scale traveling ionospheric disturbances propagate across the equator during UT 1-6, while HF Doppler oscillations maximize later during UT 6-24, revealing a timing offset between integrated TEC responses and reflection-height dynamics. Southern Hemisphere O/ ratio depletion observed by TIMED/GUVI provides compositional context consistent with the faster positive-phase decay there, although concurrent Northern Hemisphere GUVI coverage is limited during this interval. These findings highlight the value of multi-observable diagnostics for developing testable constraints on storm-time mechanisms and improving sector-specific space weather nowcasting capabilities.

With remote sensing observations immediately after the March 11, 2011, Japanese earthquake and tsunami, we detected a significant increase in radiation at the top of the atmosphere. Later, on March 21, 2011, we observed an ionospheric anomaly associated with the largest radioactive release. This coincides with a reported radioactive gas leak from the Fukushima Daiichi Nuclear Power Plant (FDNPP). We explain this phenomenon by stating that radioactive pollution due to its air ionization activity can drastically change the atmospheric boundary layer conductivity and produce anomalous atmospheric variations. Both thermal and ionospheric anomalies can be observed by geospace sensing techniques both from satellites (IR sensors and ionospheric probes) and from the ground (GPS receivers, ground-based ionosondes, VLF propagation sounding). We validate this approach with the two other nuclear power plant emergency events in Three-Mile Island (USA) and Chernobyl (former USSR) and stationary sources such as the Gabon Natural Nuclear Reactor.

We study critical lithosphere/atmosphere /ionosphere coupling processes that precede earthquake events. Soon after the M7.8 and M7.5 in Kahramanmaraş, Türkiye on Feb 6, 2023, Kahramanmaraş earthquakes, we started collecting and processing multi-parameter data from ground, atmosphere, and satellite observations, such as 1/ Vertical static pendulums data from the European network; 2/ Hydrogeochemical data for electrical conductivity and major ion contents from the spring water samples near Kahramanmaraş ; 3/ Outgoing long-wavelength radiation (OLR) obtained from satellites NPOESS; 4/ Ionospheric plasma observations from China/Italy Seismo-Electromagnetic Satellite (CSES1);5/Electron density variations in the ionosphere via GPS Total Electron Content (GPS/TEC) and 6/ Atmospheric chemical potential (ACP) obtained from NASA assimilation models. We have detected two temporal groups of pre-earthquake anomalies: A/few months in advance - hydrogeochemical anomalies lasting up to six months and vertical static pendulums lasting two months ahead of the seismic rupture and B/few days in advance - OLR and ACP anomalies showed an abnormal increase on Jan 15-30, along with the plasma electron and oxygen ion density from the CSES1 satellite which is highly correlated with electron density variations in the ionosphere from GPS/TEC. Two groups of identified anomalies relate to different stages of Kahramanmaraş earthquake preparation processes. The first type was linked to the crustal deformation phase and was associated primarily with the coupling processes of the lithosphere-atmosphere. Based on the cross-event analysis of major seismicity in the regions, we found similarities in the pre-earthquake pattern occurrence between the M7.8/M7.5 2023 Kahramanmaraş sequence and the M7.2 Van Earthquake of 2011 and two other major events.We show that we could extract new information about the different stages of earthquake preparation processes by combining ground and near-space data according to the physical concept of LAIC.

The China Seismo-Electromagnetic Satellite (CSES), with a sun-synchronous orbit at 507 km altitude, was launched on 2 February 2018 to investigate pre-earthquake ionospheric anomalies (PEIAs) and ionospheric space weather. The CSES probes manifest longitudinal features of four-peak plasma density and three plasma depletions in the equatorial/low-latitudes as well as mid-latitude troughs. CSES plasma and the total electron content (TEC) of the global ionosphere map (GIM) are used to study PEIAs associated with a destructive M7.0 earthquake and its followed M6.5 and M6.3/M6.9 earthquakes in Lombok, Indonesia, on 5, 17, and 19 August 2018, respectively, as well as to examine ionospheric disturbances induced by an intense storm with the Dst index of − 175 nT on 26 August 2018. Anomalous increases (decreases) in the GIM TEC and CSES plasma density (temperature) frequently appear specifically over the epicenter days 1–5 before the M7.0 earthquake and followed earthquakes, when the geomagnetic conditions of these PEIA periods are relatively quiet, Dst: − 37 to 19 nT. In contrast, TEC and CSES plasma parameter anomalies occur globally in the southern hemisphere during the storm days of 26–28 August 2018. The CSES ion velocity shows that the electric fields of PEIAs associated with the M7.0 earthquake are 0.21/0.06 mV/m eastward and 0.11/0.10 mV/m downward at post-midnight/post-noon on 1–3 August 2018, while the penetration electric fields during the storm periods of 26–28 August 2018 are 0.17/0.45 mV/m westward/downward at post-midnight of 02:00 LT and 0.26/0.26 mV/m eastward/upward at post-noon of 14:00 LT. Spatial analyses on CSES plasma discriminate PEIAs from global effects and locate the epicenter of possible forthcoming large earthquakes. CSES ion velocities are useful to derive PEIA- and storm-related electric fields in the ionosphere.

The full range of effects of strong volcanic eruptions on the electrical characteristics of the atmosphere is not yet fully understood. On the 10 April 2023, the largest eruption in recent decades of the Shiveluch volcano in Kamchatka occurred. At the same time, a sharp increase in electron concentration was observed in the F layer of the ionosphere above the volcano. Simultaneously, at a distance of 450 km from the volcano, an intense anomaly was observed in the vertical component of the electric field potential gradient in the surface atmosphere. At this distance, the anomaly could not have been caused by a space charge of volcanic ash. The article examines the atmospheric–electrical effects of a volcanic eruption and proposes a physical mechanism for these phenomena. The formation of strong electric field positive jump as result of volcano eruption was confirmed by the consecutive Shiveluch volcano eruption on the 18 August 2024.

Abstract: Recent years demonstrate the increased attention to radon from two scientific directions. After neglecting radon as earthquake precursors in 1990-th it becomes again the subject of earthquake-forecast papers discussions due to growing networks of the radon monitoring in different countries, especially, the technologies of real-time radon measurements where the gamma-spectrometers become the leader of interest as the sources of 222Rn identification. The second fast developing direction is including the radon in the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) models as a source of the boundary layer ionization. And here we encounter with second direction which is not connected with the earthquake forecast problems. It is the role of air ionization by radon as a source of the Global Electric Circuit (GEC) modification. In this publication we try to unite all these problems to present more complex view on radon as important element of our environment.

The paper presents the author’s vision of the problem of earthquake hazards from the physical point of view. The first part is concerned with the processes of precursor’s generation. These processes are a part of the complex system of the lithosphere–atmosphere–ionosphere–magnetosphere coupling, which is characteristic of many other natural phenomena, where air ionization, atmospheric thermodynamic instability, and the Global Electric Circuit are involved in the processes of the geosphere’s interaction. The second part of the paper is concentrated on the reliable precursor’s identification. The specific features helping to identify precursors are separated into two groups: the absolute signatures such as the precursor’s locality or equatorial anomaly crests generation in conditions of absence of natural east-directed electric field and the conditional signatures due to the physical uniqueness mechanism of their generation, or necessity of the presence of additional precursors as multiple consequences of air ionization demonstrating the precursor’s synergy. The last part of the paper is devoted to the possible practical applications of the described precursors for purposes of the short-term earthquake forecast. A change in the paradigm of the earthquake forecast is proposed. The problem should be placed into the same category as weather forecasting or space weather forecasting.

Recent years have seen increased attention given to radon from two scientific directions. After neglecting radon as an earthquake precursor in the 1990s, it has become the subject of discussions in earthquake-forecast papers due to growing networks of radon monitoring in different countries, particularly the technologies of real-time radon measurements where gamma spectrometers are of great interest as sources of 222Rn identification. The second fast-developing direction involves radon in Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) models as a source of boundary layer ionization. Here we address the second topic, which is not connected with the earthquake forecast problems, namely, the role of air ionization by radon as a source of the Global Electric Circuit (GEC) modification. In this publication, we try to unite all of these problems to present a more complex view of radon as an important element in our environment. Special attention is paid to the dependence of radon variability on environmental conditions.

In this paper, we analyze the effect of the preparation of the Chuya earthquake on September 27, 2003, the strongest event in the Altai-Sayan folded region for the entire instrumental period of seismological observations, on meteorological characteristics (temperature, relative humidity, atmospheric chemical potential correction, latent heat of evaporation, and the mean and dispersion values of these data) and their spectral characteristics in the Gorny Altai region. The meteorological and spectral characteristics are shown to change for a certain time before the main shock. The spectral characteristics distinctly change both during the preparation of the main shock and during the aftershock process.

A large number of processes and phenomena that occur both in the Earth’s layers (Veronis et al., 1999; Beletsky et al., 2003; Bochev and Dimitrova, 2003; Balan et al., 2008; Utada et al., 2011; Simões et al., 2012; Nina et al., 2020b) and in outer space (Inan et al., 2007; Srećković et al., 2017; Nina et al., 2018; Nina et al., 2021; Kolarski et al., 2022) constantly affect the terrestrial atmosphere. Although the effects that phenomena created in different areas produce in atmospheric layers depend on their characteristics and the observed geographical location, changes can very often be detected in large areas that include several atmospheric layers. Also, there are numerous influences on one atmospheric area (Nina et al., 2017; Silber and Price, 2017). In addition, changes in the atmosphere as a medium, in which other processes take place, have an impact on various processes and technologies in modern life (Jakowski et al., 2005; Stankov et al., 2009; Su et al., 2019; Nina et al., 2020a; Hunting et al., 2021). Therefore, the monitoring and understanding of spatio-temporal atmospheric changes are important for research in a number of scientific disciplines as well as for geoinformation technologies. Here, first of all, the importance of research into atmospheric changes related to natural disasters should be emphasized (Molchanov et al., 2004; Price et al., 2007; Maurya et al., 2016; Kumar et al., 2017; Vyklyuk et al., 2017, 2019; Manta et al., 2020; Malinović-Milićević et al., 2023). For example, the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model based on the effects of ionisation provided by radon released from active tectonic faults before earthquakes is created in Pulinets et al. (2022). In this Research Topic, studies of solar flare and seismic processes (possible) influences on the atmosphere are presented. Here, we briefly review and summarize these articles. Barta et al. analysed the ionosphere during influences of solar flares that occurred on 5 and 6 December 2006. This study is based on data obtained in ground-based (by ionosonde and very low frequency (VLF) radio signals) and satellite (by GNSS and DEMETER satellites) observations. The obtained results show 1) an increase in VTEC (2%–5%) OPEN ACCESS

The noise-like behavior of geomagnetic anomalies observed in Tlamacas station (the Popocatepetl volcano, Mexico), linked to the ionization produced by intensive radon release, is presented in the experimental part of the study. The magnetic-field perturbations produced by electrical currents due to micro-discharges on the terrain irregularities are considered in a theoretical model. The simulations demonstrated that the discharge mechanism can generate perturbations with magnitudes of up to 1–10 nT in the ultra-low frequency (ULF)) range of 10−3–10−1 Hz. ULF Magnetic-field perturbations can be higher within storm-weather conditions under an accumulation of electric charges in clouds in the mountainous regions.

A study of temporal variations of the complex relative δ-Barbier parameter (δBarbier) was carried outto evaluate its effectiveness in the search for seismo-ionospheric precursors. For this purpose, its behavior(according to 15-min measurements of ionospheric parameters) was considered before two strong earthquakesfor which seismo-ionospheric precursors had already been detected. The first earthquake (with magnitudeM = 6.3) occurred on April 6, 2009 (L’Aquila, Italy) at an epicentral distance of ~93 km from the Romeground-based vertical ionospheric sounding station, and the second earthquake (with magnitude M = 7.2)occurred on January 30, 2016, while its epicenter was ~117 km from the ground-based vertical ionosphericsounding station located on the territory of the Paratunka Kamchatka complex geophysical observatory. Inboth cases, specific features were identified in the behavior of the δBarbier parameter that coincided in timewith the previously detected ionospheric precursors of these earthquakes. This allows us to conclude that theeffectiveness of using the δBarbier parameter in the search for seismo-ionospheric precursors has been successfullyverified

There have been reports about anomalies in mobile geomagnetic data before earthquakes; however, whether it can be used as an indicator for identifying potential earthquake areas was not be explored. In this study, we propose two parameters for earthquake forecasting based on annual mobile geomagnetic observation data. The spatial horizontal and three components’ changes are calculated in each year and then used to forecast moderate–large earthquakes (M ≥ 5.0) in southwest China in the subsequent period. It is found that earthquakes are more likely to occur in low H- or F-value regions. We statistically assess their forecasting performance by using Molchan’s error diagram, and the results indicate that there is considerable precursory information in the spatial H and F values. It is concluded that mobile geomagnetic observations might be useful in middle-term earthquake forecasts in the study area. We discuss the physical mechanisms of H and F values to explain their reasonability. The methodology proposed in this study could be helpful in finding out the optimal solution for annual mobile geomagnetic measurements for middle-term earthquake forecasting.

The noise-like behavior of the geomagnetic anomalies observed in Tlamacas station (volcano Popocatepetl, Mexico), linked to the ionization produced by intensive radon release, are presented in the experimental part of this study. The magnetic field perturbations produced by charge spreading currents within the fair-weather electric field are considered in the theoretical model based on the electrode. The electric charges are generated by the air ionization due to radon emanation. The simulations demonstrated that the ionization of the air leads to magnetic field perturbations of about 0.001–0.1 nT in the ULF (ultra low frequency) range 10−3–10−1 Hz. Magnetic field perturbations can be higher when the radon emanation occurs in a region with terrain irregularities.

The global response of the ionosphere to intense geomagnetic storms and variations of the solar activity according to the solar flux F 10.7 is considered. As a source of information, data on total electron content (TEC) calculated from measurements of the global network of receivers of the global navigation satellite systems are used. Unlike many publications, where the effects of individual unique geophysical events are studied in detail (for example, the superstorm of October 28, 2003), we considered the effects of strong storms ( Dst ≤ –80 nT) starting from 2005. The main attention was paid to the dependence on the onset time of the main phase of the storm relative to local time/longitude, as well as the dependence of the intensity of the ionospheric response on latitude. To display the ionospheric effects of magnetic storms, a visual image was used – a two-dimensional representation in the day-local time format, which was used to visualize ionospheric earthquake precursors. This approach also makes it possible to visualize the effects of solar activity variations according to the F 10.7 index and to distinguish them from ionospheric variations during geomagnetic storms. As a result, it was possible to create a generalized global “pattern” of a geomagnetic storm in the Earth’s ionosphere.