Abstract The sporadic E (Es) layer is a thin metallic‐ion layer in the lower ionosphere whose formation is strongly influenced by neutral‐wind shear. Regional observations have revealed multiday variations in Es‐layer parameters during sudden stratospheric warming (SSW) events, but their large‐scale zonal structure remains unclear. Using near‐global Formosa Satellite‐3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT‐3/COSMIC) radio‐occultation observations, we examine the Es‐layer‐related occurrence rate (EsOR) during the January 2013 SSW. Neutral winds from the specified‐dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (SD‐WACCM‐X) are used to diagnose vertical ion convergence efficiency (VICE). Northern Hemisphere midlatitude EsOR exhibits a pronounced 10–16‐day variation dominated by a westward‐propagating zonal‐wavenumber‐1 (W1) structure. A corresponding period, propagation direction, and zonal structure are resolved in VICE. Latitude–height diagnostics further show that the 10–16‐day W1 zonal‐wind amplitude increased during the SSW; mode separation indicates that the quasi‐10‐day W1 component provides the principal event‐related enhancement within the broader band. The agreement among EsOR, VICE, and modeled winds supports planetary‐wave‐scale modulation of the E‐region wind‐shear and ion‐convergence environment. This event‐specific association does not imply that W1 alone determines individual Es‐layer formation.

Ground-based Global Navigation Satellite System (GNSS) total electron content (TEC) measurements have been widely used to investigate the ionospheric impacts of terrestrial activities such as, earthquakes, tsunamis, and volcanic eruptions. However, the potential influence of surface disturbances-induced receiver and antenna motion on TEC observations remains insufficiently explored. On April 3, 2024, an M 7.4 earthquake struck Hualien, Taiwan, at 07:58:12 local time, followed by an M 6.4 aftershock 13 min later. This event provided an opportunity to examine possible receiver motion effect manifested as TEC disturbances or fluctuations. In this study, we analyzed TEC along the line-of-sight (LOS) between geostationary Earth orbit (GEO) satellites and ground-based GNSS receivers located near the epicenters. TEC fluctuations were observed within 1 min following both the main shock and the aftershock, with ampli- tudes of 0.1–0.2 TECU and 0.05–0.1 TECU, respectively. These fluctuations have been rarely reported previously and we compared them with coseismic displacements derived from kinematic precise point positioning (PPP). The tendencies of the TEC fluctuations aligned with displacements projected onto the LOS-normal plane, and least-squares linear regression indicated a proportional relationship of approximately 0.03 TECU per 10 cm. In contrast, displacements projected along the LOS showed no similar tendencies with TEC. These results suggest that TEC fluctuations within 1 min after the earthquakes may be associated with the LOS movements between the GNSS receivers and the GEO satellites during the two Hualien seismic events.

Our Earth experienced an extreme solar storm on the Mother's Day weekend from 10-12 May 2024, leading to the most severe geomagnetic storm in the past two decades. In addition to significant changes in the near-Earth space environment from the magnetosphere to the ionosphere, this study primarily shows notable disturbances in the atmospheric electric field (Ez), as recorded by the electric field mill of the MVP-LAI (Monitoring Vibrations and Perturbations in the Lithosphere, Atmosphere, and Ionosphere) system located in LeShan (29.6 degrees N, 103.9 degrees E; L-shell value similar to 1.12), Sichuan Province, during the initial and main phases of the storm. Here, we employed a data-adaptive method to identify storm characteristics by resolving complex changes in atmospheric Ez over short to long periods. For further investigating causal mechanisms, we also analyzed the collocated measurements of the MVP-LAI system, including atmospheric pressure, geomagnetic fields, ionospheric total electron content (TEC), and High-frequency Doppler echoes over LeShan, as well as the ionosonde echoes at DaoFu (31.0 degrees N, 101.12 degrees E) and the magnetic field observation from Geostationary Operational Environmental Satellite (GOES) 16 at similar to 6.6 Earth radii. The key finding is the nearly coincident disturbances from space to the atmospheric Ez at similar to 20:00 UT, which indicated the possible impact of electrodynamic changes on the atmosphere at the time of storm onset. Short-period perturbations (with frequency >1 mHz) observed in the ionospheric TEC, atmospheric pressure and electric field suggest the appearance of acoustic resonance in the atmosphere during the storm's main phase.

The occurrence of landslides is considered to be preceded by the instinct of rock breaking and strata failure, which could lead to the emission of electromagnetic radiation. We eliminated the influences from solar activities, lightening, artificial noises, and seismogeneric fault to examine the relationship between magnetic perturbations and landslides. The correlation coefficient method is further employed to investigate the in-phase and out-of-phase relationship between geomagnetic data collected from approximately 100 stations. The analytical results indicate that strong positive (> 0.8) and strong negative (< − 0.8) correlation coefficients associated with landslides are distributed within areas with an incredibly large radius, approximately 500 km. Two interfaces between strong positive and negative correlation coefficients were found extending from the landslide sites, aligning with the direction of the landslide flow and its orthogonal direction. The significant discrepancy in correlation coefficients across adjacent areas implies the existence of electric currents. Using the Biot-Savart Law, we calculated the landslide-associated magnetic perturbations, and a rough match between numerical and observational results demonstrates that electromagnetic perturbations arise several minutes before landslide occurrence.

Interhemispheric Field-Aligned Currents (IHFACs) serve as the channels connecting the ionospheric current systems over the Northern and Southern Hemispheres and maintaining the balance between them. The directions of the IHFACs represent the inflow and outflow currents from one hemisphere to the other. In this study, we investigated the mechanism for the south-north abnormal reversals of the IHFAC directions at middle and low latitudes by analyzing the field-aligned current density from Swarm, lower thermospheric wind from TIDI and ICON, and ionospheric conductivity derived from IRI-2020 and Nrlmsise-00 models. The results suggest that besides the geomagnetic geometry, the south-north hemispheric asymmetry of ionospheric conductance controls the IHFAC reversal over the American-Atlantic region. By contrast, over the Asian-Pacific region, the IHFACs exhibit multiple reversals across longitudes from similar to 60 degrees E to 150 degrees W without being controlled by conductance and geomagnetic geometry. It is surprising that variations in the thermospheric winds are particularly strong over the Asian-Pacific region, playing a significant role in modulating the IHFAC directions. The study reveals the cause of the IHFAC directions in different seasons and regions, and promotes the understanding of the connection between the ionospheric dynamo in the two hemispheres.

Recently, astronomers discovered unusual Einstein cross images of the galaxy HerS-3, which feature a bright central spot. Motivated by studies of images produced by regular stars, it has been proposed that optical appearances caused by compact stars acting as gravitational lenses may account for this central bright spot. We further suggest that images produced by regular stars exhibit additional characteristics distinct from those of ordinary black holes, such as the possible partial or complete absence of secondary images. These phenomena may serve as favorable observational criteria for identifying regular stars in future searches.

Abstract On 10 May 2024, an interplanetary coronal mass ejection‐driven shock impacted the dayside magnetopause, compressing it to ∼5 RE. A northward interplanetary magnetic field suppressed dayside reconnection and allowed a clear investigation of the magnetosphere response. We use coordinated GOES and THEMIS observations to examine the magnetopause motion and its boundary layer evolution. Our study provides, for the first time, ion energy flux spectra, pitch angle distributions, and ion moments derived from the GOES‐16 data. The energy flux spectrum from GOES‐16 reveals a geostationary magnetopause crossing 32 s prior to the magnetosheath magnetic field turning southward. The magnetopause was compressed at a speed of ∼300 km s−1, with the depletion layer thickening by a factor of 3.8. We identify a localized compressed region that expands rapidly earthward. Within this region, a rare three‐energy‐level ion structure is observed, indicating the transport of ions from a plasmaspheric plume.

A solar storm can trigger severe geomagnetic and ionospheric disturbances, and activities originating from the Earth’s surface can do so as well. This presentation will introduce the sudden changes in the ionospheric plasma structure and electrodynamics after large lithospheric disturbances, such as earthquakes/tsunamis and volcanic eruptions. The main focus will be on the two significant events of the magnitude 9.0 Tohoku earthquake/tsunami (38.3°N 142.4°E) in the northeastern sea area of Japan on 11 March 2011, and the undersea volcanic eruption in Tonga (20.6°S 175.4°W), Central Pacific, on 15 January 2022. This presentation will also discuss the main characteristics of disturbances in ionospheric structures and electrodynamics. Investigating the two events enhances our comprehension of the sensitivity of the ionosphere response to lithospheric activities.

Mars has been a primary focus of planetary science, with significant advancements over the past two decades across disciplines including geological evolution, surface environment, and atmospheric and space science. However, the rapid growth of the related literature has rendered traditional manual review methods increasingly inadequate. This inadequacy is particularly evident in interdisciplinary research, which is often characterized by dispersed topics and complex semantics. To address this challenge, this study proposes an automated analysis framework based on natural language processing (NLP) to systematically review the Martian research in Earth and space science over the past two decades. The research database contains 151,196 Mars-related sentences extracted from 10,655 publications spanning 2001 to 2024. Using machine learning techniques, the framework clusters Mars-related sentences into semantically coherent groups and applies topic modeling to extract core research themes. It then analyzes their temporal evolution across the Martian solid, surface, atmosphere, and space environments. Finally, through sentiment analysis and semantic matching, it highlights unresolved scientific questions and potential directions for future research. This approach offers a novel perspective on the knowledge structure underlying Mars exploration and demonstrates the potential of NLP for large-scale literature analysis in planetary science. The findings potentially provide a structured foundation for building an interdisciplinary, peer-reviewed Mars knowledge base, which may inform future scientific research and mission planning.

At 23:58:08 UT on April 2, 2024, an M7.4 earthquake occurred near Hualien, Taiwan region, triggering geomagnetic variations. Seismic waves typically induce geomagnetic disturbances that exhibit time delays that are dependent on epicentral distance in previous studies. In this study, simultaneous perturbations in three-component geomagnetic field were observed within 114 km of the epicenter. The out-of-phase perturbations in the Z-component between the geomagnetic stations near the epicenter suggest a local electric current triggered by the earthquake. The height and orientation of the currents were estimated to be approximately 99 km and 247 ° (southwest), respectively. The magnetic field and high-frequency Doppler sounder observations indicate that acoustic waves are triggered by the earthquake. This was consistent with the sound propagation of the NRLMSISE−00 atmospheric model. The acoustic waves propagate from the ground to ionosphere, causing plasma to move across the Earth’s magnetic field, which leads to the generation of electric current. This study suggests that earthquake-triggered acoustic waves can change the dynamics of the ionosphere. These findings provide new insights into earthquake-ionosphere coupling, indicating that earthquakes can trigger temporal ionospheric currents near the epicenter.

This study reveals that the magnetotelluric (MT) method can detect the responses of the ionospheric E-region to the annual solar eclipse on June 21, 2020. The MT method not only detected a significant reduction in the solar quiet current by approximately 3.3 h over Lijiang during the obscuration but also, for the first time, observed waves with periods ranging from a few to dozens of minutes in the electric field due to the eclipse. The evolution of electric and magnetic fields suggests nonstationary changes in the ionospheric E-region structures during and after the eclipse.

The ionosphere owns a complex electric current system mainly driven by the ionospheric electric field and thermospheric wind. Changes in current can generate geomagnetic signals that can be observed both on the ground and in space. In this study, we analyzed the ionospheric current in the Asia-Oceania region by utilizing geomagnetic data collected from magnetometers of ground-based observatories and SWARM satellites at ~450 km altitude. The results present the geomagnetic variations at the two distinct altitudes, encompassing longitudinal, latitudinal, and seasonal variations. Furthermore, the Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) was employed to simulate the associated geomagnetic signals. This study is the first to combine dense geomagnetic data from multiple altitudes and simulations to understand the ionospheric current in the Asia-Oceania region. The differences between the observational geomagnetic signals at different altitudes, along with the simulations, reveal a unique current structure that has not been previously discovered. The findings provide a new understanding of the intricate evolution of the current systems, which contributes to our knowledge of the electric dynamics within Earth's ionosphere.

Stress change in ferromagnetic-minerals-bearing rocks can change the rock magnetization and lead to the variation in magnetic field, known as the piezomagnetic effect, which is a possible mechanism for the earthquake-associated electromagnetic (EM) signals. Previous studies are mostly based on elastostatics to obtain a static piezomagnetic field generated by a dislocation or pressure source, which is not sufficient to explain the observed time-varying EM signals during an earthquake. In this study, we investigate the time-varying EM response generated by an earthquake due to the piezomagnetic effect. We propose an analytically-based method to simulate the seismic and EM fields in a horizontally layered model, in which the coupled elastodynamic and Maxwell's equations are solved in the frequency-wavenumber domain. The time-space-domain seismic and EM responses are obtained through the Hankel transform and inverse Fourier transform. We conduct numerical simulations to investigate the properties of the EM responses to earthquakes. The results show that variations in not only magnetic fields but also electric fields can be generated due to the piezomagnetic effect. For an M-w 6.0 earthquake, a receiver with an epicentral distance of 85 km can receive coseismic electric and magnetic fields of similar to 0.1 mu V/m and similar to 0.1 nT, which are detectable by current EM equipment, demonstrating that the piezomagnetic field is an effective mechanism for the generation of earthquake-associated EM disturbances. We apply the method to simulating the coseismic EM signals observed in an actual earthquake and find that the piezomagnetic effect possibly contribute to the observed data.

The E s layer is a thin layer that concentrates metallic ions in the mesosphere and lower thermosphere （MLT） region.When it occurs,it can affect the performance of the Global Navigation Satellite System and high/very high frequency （HF/VHF） radio communications.Previous studies mainly focused on the one-dimensional structure of E s layer in the vertical direction.However,due to the limitation of observations,the horizontal structure of E s layers is not yet fully understood.This study investigated the horizontal structure of E s layers using amateur radio data in the European sector during the summer of 2020.Statistical analysis shows that the horizontal structure of E s layer is mainly elongated in the east-west direction.In addition,we investigated the dynamics of the E s layers,which primarily propagates in the northeast-southwest direction with a speed of 50-200 m/s.The results provide us a way for obtaining the horizontal structure and dynamic features of E s layers,which can help improve our understanding of the formation and evolution of E s layers.

This study examines the complex interrelationships among ionospheric NmF2 variations, solar activity F10.7 index, and crustal movements preceding the 2011 Tohoku-Oki earthquake. NmF2 from 5 ionospheric stations (Yakutsk, Khabarovsk, Wakkanai, Kokubunji, and Jeju) is studied together with vertical movement observed by Hi-net tilt meters in Japan. Results showed that while daytime NmF2 typically correlates with solar activity (F10.7 solar radio flux), significant deviations were observed during specific periods. During these intervals, NmF2 variations did not correlate with space weather parameters as expected but correlate with the vertical ground motion. We explain these phenomena as due to the enhanced dynamo electric field, which is produced originally by the vertical ground motion. Our findings suggest that the ionosphere before the large earthquake is influenced by the complex Lithosphere-Atmosphere-Iono sphere interaction such as crustal movements, acoustic-gravity waves, and dynamo electric field variations. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The propagation of seismo-traveling ionospheric disturbances (STIDs) is generally observed at one specific altitude layer. On 2 April 2024, a Mw 7.4 earthquake struck Hualien, which was the biggest earthquake since the 1999 Chi-Chi earthquake in the Taiwan region. In this study, a co-located vertical monitoring system combined with the observation of two horizontal layers in the ionosphere was utilized to study the STIDs associated with the Hualien earthquake. The vertical monitoring system can capture disturbances from the ground surface up to a height of ~350 km. In addition, changes in electric currents and the TEC (total electron content) at two horizontal layers, ~100 km and ~350 km, were monitored by permanent geomagnetic stations and a ground-based GNSS (global navigation satellite system) receivers network, respectively. The observations from this four-dimensional (4D) monitoring network show that the STIDs at a height of ~100 km associated with Rayleigh waves can propagate as far as 2000 km from the epicenter, while at an altitude of ~350 km, they can only propagate to about 1000 km. At an altitude of about 200 km, STIDs were also captured by a high-frequency Doppler sounder in a vertical monitoring system, which was consistent with the results in the geomagnetic field. The results from the 4D monitoring network suggest that the STIDs associated with Rayleigh waves exhibit different propagation ranges at various altitudes and prefer to propagate at low ionosphere layers. The vertical propagating waves typically only reach the bottom of the ionosphere and struggle to propagate to higher regions over long distances.

This study reports an extreme ionospheric plasma depletion event over the Eastern Pacific from postmidnight to early morning during the superstorm's recovery phase on 21 November 2003 observed by the DMSP F13, ROCSAT-1, GRACE, and CHAMP satellites, and two ground-based GPS receivers. The depletion and its interhemispheric geomagnetic conjugate effect occurred between similar to 40 degrees S and 40 degrees N geomagnetic latitudes. This suggests a possible extremely long-range flux tube connection with an apex altitude exceeding 6,000 km over the geomagnetic equator. Notably, the observed altitude for midlatitude depletions of equatorial origin in the morning is the highest ever reported. Previous studies have primarily observed the extension of equatorial plasma bubbles to middle latitudes in the post-sunset hours. The continuous upward vertical plasma drift, supported by ROCSAT-1 and TIE-GCM simulations, may drive the unprecedentedly strong latitudinal extension of these midlatitude plasma depletions in the midnight-to-morning sector.

The seepage of pore fluids in subsurface rocks under a pressure gradient can alter the stress state of the strata and induce magnetic variation through the piezomagnetic effect. This is a possible reason for the generation of geomagnetic field anomaly. Previous studies on the piezomagnetic effect mainly focused on the steady magnetic field changes caused by static stress, while the dynamic piezomagnetic response associated with fluid seepage processes has not been adequately studied. In this paper, we employ the finite element method to simulate the dynamic piezomagnetic response during gas injection and extraction processes, and investigate the characteristics of the piezomagnetic field. First, using a homogeneous model, we simulate the piezomagnetic response during the short-term rapid gas injection and the long-term continuous gas injection and extraction, respectively. Second, we investigate the effects of initial intensity and declination of the magnetization in local surface regions on the distribution of the surface magnetic field. Finally, we simulate the variations in the surface magnetic field induced by piezomagnetic effects during the gas injection and extraction processes in the Hutubi underground gas storage. The results indicate that: (1) For short-term rapid gas injection, the magnetic field reaches its peak at the end of the injection and subsequently decays gradually over time. The peak amplitude of the magnetic field depends on the rock permeability, while the peak time is nearly unaffected by the permeability. In contrast, for long-term continuous gas injection and extraction, the magnetic field reaches its peak several days after the injection rate attains its maximum, followed by a gradual decay. In this case, both the peak amplitude and peak time are controlled by the permeability. (2) The total intensity of the surface magnetic field is jointly regulated by the initial intensity and declination of the magnetization of the rocks, whereas the polarity distribution is primarily determined by the magnetization direction. (3) In the Hutubi area, the simulated surface magnetic field intensity exhibits an initial increase followed by a decrease during the injection-extraction process, which shows good consistency with the magnetic field changes observed during the injection period. The results of the present study provide a theoretical basis for future applications of geomagnetic anomalies in the inversion of the subsurface fluid migration, and also offer valuable insights into the mechanisms of the geomagnetic anomalies observed prior to earthquakes.

An earthquake doublet occurred in Turkey on 6 February 2023, with propagating Rayleigh waves triggering perturbations in the ionospheric total electron content (TEC) for both the M 7.8 earthquake (EQ7.8) and the M 7.5 earthquake (EQ7.5). A discrepancy between the velocities of TEC perturbations and Rayleigh waves has been noted, but its causes remain unresolved in previous studies. In this study, we calculated the velocities of TEC perturbations and the frequency-dependent velocities of Rayleigh waves, considering their intrinsic dispersive characteristics. To retrieve TEC, we utilized ground-based Global Navigation Satellite System (GNSS) data from geostationary Earth orbit (GEO) satellites to mitigate the effects of moving ionospheric pierce points (IPPs) from orbiting satellites. The results reveal that the velocities of TEC perturbations (similar to ${\sim} $2.60 km/s for EQ7.8 and similar to ${\sim} $2.77 km/s for EQ7.5) do not align with the velocities of Rayleigh waves across the entire frequency band (2.4-3.0 km/s for EQ7.8 and 2.6-3.5 km/s for EQ7.5). However, they are comparable within specific periods of 10-30 s due to dispersion effects for both EQ7.8 and EQ7.5. The dispersive Rayleigh waves, which exhibit significant amplification in the 10-30 s period range, are identified as the primary source of the pronounced coseismic TEC perturbations, particularly for EQ7.5.

The sudden cutoff of solar radiation caused by the solar eclipse could cause significant changes in the thermosphere and ionosphere, considering the fact that the solar radiation plays a significant role in their dynamical processes. In this study, the thermospheric neutral wind recorded by the Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) on the Ionospheric Connection Explorer (ICON) spacecraft and metero radar were analyzed to examine the variations in thermospheric wind during and after the 21 June 2020 annular solar eclipse over the East China area. The neutral wind observations showed direct evidences that the solar eclipse disturbed the mesosphere and low thermosphere for more than 10 hours. The clear enhancement of the meridional wind during the moon obscuration and sharply decreased meridional wind after local sunset suggested that a large-scale oscillation was caused by the solar eclipse, which persisted from daytime to nighttime.