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In this work, we present ArchaeoPyDating, a new version of the archaeo_dating Matlab software used for archaeomagnetic dating. This updated version introduces a transition from the original Matlab code to Python, enabling the software to be presented as an online tool. By offering a web‐based interface, ArchaeoPyDating eliminates the need for licenses, program installations, or programming expertise, making it widely accessible to users through various devices and browsers. This enhanced accessibility holds great potential for popularizing the archaeomagnetic dating method. This study presents both the new online version of the tool and a Python module that encompasses all the essential classes and functions required for conducting archaeomagnetic dating in a command‐line environment, which can be useful for advanced users. [ABSTRACT FROM AUTHOR]

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Copyright of Reviews of Geophysics & Planetary Physics is the property of Editorial Office of Reviews of Geophysics & Planetary Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

(Top) Variation of the earth's magnetic inclination along with diverse geographical locations of representative events. (bottom) The interaction between the earth's magnetic inclination and acoustic pulse generated from the events. Note that the events that occurred in the mid-latitudes of the southern and northern hemispheres show strong single-beam directivity, whereas the events situated in the polar and equatorial regions show omni-directional and dual-beam directivity. [Display omitted] Influence of the geomagnetic field on ionospheric disturbances associated with acoustic waves has been widely reported and unanimously agreed upon for the mid-latitude north and mid-latitude south regions, while elaborate studies in this regard are scarce for the polar and equatorial regions. In this study, we present a holistic overview that characterizes the ionospheric directivity from a global perspective considering observations from various natural case studies and anthropogenic phenomena and compare the results with the numerically simulated TEC anomaly. Our focused approach highlights that ionospheric directivity is omnidirectional and bidirectional (or dual-beam) for magnetically polar and equatorial regions, respectively. The mid-latitude north and south domains were also looked upon where the ionospheric directivity is strongly unidirectional (or single-beam). Further, the results of our numerical simulation model appear to complement well with the observations. [ABSTRACT FROM AUTHOR]

This paper examines the response in geomagnetic-field variations caused by the 2020–2023 earthquakes with magnitudes Mw ≥ 7.0 in the Aegean Sea and eastern Turkey. A detailed comparison of high-precision observations of the geomagnetic field and seismograms recorded at complex geophysical observatories within a radius of 3000 km from the epicenters was carried out. The joint analysis involves averaged 1-s data on the rate of change of the magnetic field and records from broadband seismic stations. Their characteristics are assessed in both in time and frequency domains. The spectral characteristics of body and surface waves are separately compared with those of the geomagnetic signal. It is shown that the beginning of disturbance in the magnetic field at each observatory strictly coincides with the arrival of the P-wave and intensifies with the arrival of S-waves. The maximum geomagnetic disturbance is caused by surface waves. The amplitude of electromagnetic excitations is proportional to the amplitude of the parent seismic phases. Thus, the coseismic nature of the observed electromagnetic signal has been confirmed, suggesting its excitation in the Earth's crust as seismic waves propagate. [ABSTRACT FROM AUTHOR]

The results of numerical experiments, which involve calculations of the spatial distribution of the electron concentration and electric potential field formed as a result of the gradient-drift instability in the domain of developed equatorial plasma bubbles, are presented. A characteristic feature of equatorial plasma bubbles is the presence of large ratios of the electron concentration outside the plasma bubbles compared to their values inside the plasma bubbles. This creates large concentration gradients and high cross-field drift velocities relative to the Earth's magnetic field lines. These conditions lead to the occurrence of large positive values of the increment of the gradient-drift instability, resulting in the enhancement of small-scale inhomogeneities in the ionospheric plasma with spatial-temporal scales characteristic of equatorial F-scattering. The results are consistent with previous studies by the authors, aimed at investigating the peculiarities of the increment of the gradient-drift instability. Unlike the previous works of the authors, the research in this study is carried out on the basis of direct numerical modeling of the process of development of heterogeneity specified in the form of a spatially limited wave. The model describes the processes of development and intensification of initial heterogeneities with characteristic sizes of several tens of meters. Thus, gradient-drift instability may be the cause of the generation of small-scale structure at the fronts of plasma bubbles in the evening and at night. In the works of other authors, the study was carried out outside the region of ionospheric plasma bubbles. [ABSTRACT FROM AUTHOR]

The Weddell Sea Anomaly (WSA) is a phenomenon of unique intensity and geographic extent that occurs in December (Southern Hemisphere summer) over the southeastern Pacific and southwestern Atlantic oceans regions. Historically, the classic definition of the WSA refers to a situation in which the midnight NmF2 (or TEC) values are greater than the noon NmF2 (or TEC) values. However, several articles published in the last decades have shown that the WSA is a much more complex phenomenon, and its definition might need to be reformulated. This paper presents a phenomenological description of the WSA using a novel type of vertical Total Electron Content (TEC) maps, obtained from altimeter satellite TEC data. The focus of this study is on the possible connection between the WSA and the unexpected expansion and contraction periods observed on the Equatorial Ionospheric Anomaly (EIA) throughout the Southern Hemisphere. The data analysis revealed that the WSA is only one of a number of observed anomalies. Furthermore, we show a significant correlation between the behavior of the EIA and the Y component of the geomagnetic field, which maximizes in the WSA region. We then present a possible hypothesis for interpreting these results. Plain Language Summary: This contribution presents the findings of an investigation about the Weddell Sea Anomaly, an intriguing ionospheric phenomenon occurring between South America and Antarctica during December. Despite the several decades since the initial reports, the Weddell Sea Anomaly remains a topic of scientific research. The study is based on a novel self‐developed technique to produce global ionospheric maps using TEC measurements from satellite altimeter missions. The results presented provide support for the hypothesis that the Weddell Sea Anomaly may be connected to the Equatorial Ionospheric Anomaly. Furthermore, our findings indicate that the Equatorial Ionospheric Anomaly also displays anomalous behavior over the entire southern hemisphere, with the Weddell Sea Anomaly as the most contrasting of them. We also demonstrate the significant correlation that exists between the Equatorial Ionospheric Anomaly regions and the Y component of the geomagnetic field in relation to the WSA. We then present a possible hypothesis for interpreting these results. Key Points: The study of the Weddell Sea Anomaly with ULIC maps provides a new conceptual framework supporting and extending published theoriesThe new framework considers the anomaly as a mark of a more complex phenomenon that correlates significantly with the geomagnetic fieldThe manuscript presents an innovative technique for producing TEC maps that are suitable to study the climatology of the ionosphere [ABSTRACT FROM AUTHOR]

In recent years, geomagnetic observation stations have been subjected to more and more serious interference by HVDC transmission, subway, vehicles, etc. About 35 of the national geomagnetic second sampling stations have been subjected to vehicle interference, which has affected the integrity and efficiency of geomagnetic observation data. In this paper, three GM4 fluxgate magnetometers are used to carry out field interference tests on different types of vehicles in different directions, at different distances and at different speeds at Hongshan geomagnetic station, and the quantitative changes of horizontal component H, vertical component Z and magnetic declination angle D of geomagnetic field are analyzed. The results show that the dynamic vehicle driving orientation can be determined by the variation pattern of geomagnetic declination D component, and the influence of dynamic vehicle speed on geomagnetic field is small in space. A mathematical model of vehicle position change in geomagnetic field is established. Three fluxgate magnetometers can be used to invert the vehicle driving direction, driving speed and relative observation instrument position changes caused by geomagnetic stations. It provides a reference for the geomagnetic station to identify the impact of vehicle interference.

After 50 years of research on the correlation between the geomagnetic field and climate, we have gained a deeper understanding that the regulation of climate by geomagnetic field changes is far more complex than previously imagined. In this paper, we comprehensively review the research connecting the geomagnetic field and climate over the past 50 years, examining different spatial and temporal scales. Our results demonstrate a significant correlation between geomagnetic field changes and climate at various scales, including millennial-scale geomagnetic reversals, thousand-year-scale geomagnetic shifts, centennial-scale geomagnetic abrupt, and even decadal-scale variations in geomagnetic activity. The Matuyama–Brunhes geomagnetic reversal is associated with the cold climate. The increase in galactic cosmic rays (GCR) during this period gave rise to the formation of low-altitude cloud "umbrella effects", subsequently weakening the East Asian summer monsoon and intensifying the East Asian winter monsoon. Archaeomagnetic data from Mesopotamia remarkably illustrates a consistent correlation between four cold periods in the last three thousand years and a sudden increase in geomagnetic anomalies. Exploring the possibility that these geomagnetic anomalies correspond to extreme tilts of the Earth's dipole, it is hypothesized that auroral ovals and sub-auroral regions may have expanded to lower latitudes. In these regions, cosmic rays potentially interacted with a more humid troposphere, resulting in increased cloud cover and, consequently, observed atmospheric cooling. Changes in GCR flux, induced by solar activity and variations in the geomagnetic field, are proposed to have significant implications for alterations in temperate pressure systems, precipitation patterns, and atmospheric electric fields. These effects play diverse roles within the intricately coupled system of the Earth's atmosphere and the near-Earth space environment. However, it's important to note that correlation does not imply causation, and the potential mechanisms by which the geomagnetic field influences climate change are still a subject of debate. The cosmic ray-cloud mechanism is the most promising avenue for understanding how the geomagnetic field regulates climate, operating effectively across different time scales, but its exact physical mechanisms and relative importance remain unresolved issues. We propose that understanding the correlation between the geomagnetic field and climate from the perspective of solar-terrestrial multisphere coupling is crucial, with a specific focus on the response of regional climate systems to changes in regional magnetic fields. By integrating knowledge from ancient times to the present, from regional to global perspectives, we aim to form a comprehensive understanding of the correlation between the geomagnetic field and climate change. The recent successful launch of Aoke-1, which can delicately characterize magnetic field changes in the South Atlantic Anomaly (SAA), the first discovery of the centennial-scale western Pacific anomaly (WPA), and the rapid development of paleomagnetic/archaeomagnetic and paleoclimate data reconstruction have provided new historical opportunities for research on the geomagnetic field and climate. This progress indicates that the study of the impact of geomagnetic field changes on climate will be propelled to new heights.

Low Earth orbit (LEO) satellites have emerged as a primary tool for global geomagnetic field detection and model refinement, owing to their wide coverage, high resolution, and absence of geographical limitations. This paper provides a comprehensive review of the history, key characteristics, measurement accuracy, and future trends in LEO satellite magnetic field measurements. The first part of the paper outlines the evolution of LEO satellites, highlighting their unique advantages. The focus then shifts to the calibration methodology for in-orbit LEO satellite magnetic measurements, with a specific emphasis on vector magnetic field intrinsic calibration and alignment algorithms. Calibration results are presented to demonstrate the effectiveness of these methodologies. In the third section, the paper introduces the theory behind global geomagnetic field modeling. An overview of current global geomagnetic field models is provided, encompassing their sources, spatial resolutions, and other relevant attributes. The paper concludes by presenting the global morphology and features of the main field, lithospheric field, magnetospheric, and ionospheric field. Despite the significant progress enabled by LEO satellite technology, global geomagnetic field modeling faces challenges such as limited spatio-temporal resolution. To address this, incorporating near-surface observation data and continuously optimizing modeling technology are deemed essential solutions.

Abstract The navigational accuracy of sea animals and trans-ocean birds provides inspiration in using geo-magnetic field (GMF) for realizing strategic truly autonomous underwater vehicles (AUV) capable of determining their absolute position on earth, without the aid of ship-referenced acoustic baseline systems. Supervised Machine Learning algorithms are applied on the GMF intensity data obtained from NOAA World Magnetic Model for a 900 km2 within the Indian mineral exploratory area in the Central Indian Ocean, with a resolution of 50 m, considering the sensitivity of commercially available magnetometers. It is identified that, for AUVs equipped with magnetometers with a detection sensitivity of 0.1 nT, the supervisory random forest regression and decision tree algorithm trained with priori GMF data, could provide trajectory guidance to AUVs with an absolute mean position accuracy in 2D plane, with reference to the last known position from Integrated Navigation system aided initially with GPS and with acoustic positioning in underwater. Circular Error Probable (CEP 50) of 53 m and 56 m, respectively. The scalar GMF anomaly navigation demonstrated to be a viable GPS-alternative navigation system could be extended to larger areas with inclination and declination vectors, as unique identifiers.

The observation of geomagnetic field variations is an important approach to studying earthquake precursors. Since 1987, the China Earthquake Administration has explored this seismomagnetic relationship. In particular, they studied local magnetic field anomalies over the Chinese mainland for earthquake prediction. Owing to the years of research on the seismomagnetic relationship, earthquake prediction experts have concluded that the compressive magnetic effect, tectonic magnetic effect, electric magnetic fluid effect, and other factors contribute to preearthquake magnetic anomalies. However, this involves a small magnitude of magnetic field changes. It is difficult to relate them to the abnormal changes of the extremely large magnetic field in regions with extreme earthquakes owing to the high cost of professional geomagnetic equipment, thereby limiting large-scale deployment. Moreover, it is difficult to obtain strong magnetic field changes before an earthquake. The Tianjin Earthquake Agency has developed low-cost geomagnetic field observation equipment through the Beijing–Tianjin–Hebei geomagnetic equipment test project. The new system was used to test the availability of equipment and determine the findings based on big data. [ABSTRACT FROM AUTHOR]

Abstract—Based on the data of several spaced magnetic stations, the spectrum of geomagnetic variations is studied in the range of periods from two to 40 years. Special attention is paid to spectral features in the supposed range of action of intraterrestrial processes that cause geomagnetic jerks. It is shown that the detected spectral peak in the vicinity of the period of 6.5 years aligns with the previously revealed recurrence pattern of jerks with a period of three to four years; however, this peak is absent in the spectrum of solar activity. The possible wave mechanisms of the occurrence of jerks and their 6-year quasi-periodicity caused by known types of magnetohydrodynamic waves in the liquid core of the Earth, are considered, and it is shown that they are not sufficiently convincing in reproducing observations of jerks. [ABSTRACT FROM AUTHOR]

Abstract—Ground-based magnetometers and vertical ionospheric sounding stations were used to record specific variations in the geomagnetic field, caused by the perturbation in the lower ionospheric current systems, and specific variations in the upper ionospheric electron density after a strong volcanic eruption in Kamchatka, Russia, on April 10, 2023. The analysis of the measurements from two series of explosions has shown that the impact on the lower ionosphere is realized via both seismic Rayleigh waves (which are a source of acoustic waves propagating into the ionosphere), and atmospheric internal gravity waves generated by explosions. At distances up to a thousand km from the source, a repeatability of the pattern of ionospheric perturbations after each of the six volcanic explosions is discovered. At larger distances, signals from acoustic waves caused by the Rayleigh waves are clearly recorded in the ionosphere, whereas separation of the signals from atmospheric internal waves is difficult due to the influence of perturbations from other external sources. [ABSTRACT FROM AUTHOR]

The navigational accuracy of sea animals and trans-ocean birds provides inspiration in using geo-magnetic field (GMF) for realizing strategic truly autonomous underwater vehicles (AUV) capable of determining their absolute position on earth, without the aid of ship-referenced acoustic baseline systems. Supervised Machine Learning algorithms are applied on the GMF intensity data obtained from NOAA World Magnetic Model for a 900 km2 within the Indian mineral exploratory area in the Central Indian Ocean, with a resolution of 50 m, considering the sensitivity of commercially available magnetometers. It is identified that, for AUVs equipped with magnetometers with a detection sensitivity of 0.1 nT, the supervisory random forest regression and decision tree algorithm trained with priori GMF data, could provide trajectory guidance to AUVs with an absolute mean position accuracy in 2D plane, with reference to the last known position from Integrated Navigation system aided initially with GPS and with acoustic positioning in underwater. Circular Error Probable (CEP 50) of 53 m and 56 m, respectively. The scalar GMF anomaly navigation demonstrated to be a viable GPS-alternative navigation system could be extended to larger areas with inclination and declination vectors, as unique identifiers. [ABSTRACT FROM AUTHOR]

Solar particle events (SPEs) are short-lived bursts of high-energy particles from the solar atmosphere and are widely recognized as posing significant economic risks to modern society. Most SPEs are relatively weak and have minor impacts on the Earth's environment, but historic records contain much stronger SPEs which have the potential to alter atmospheric chemistry, impacting climate and biological life. The impacts of such strong SPEs would be far more severe when the Earth's protective geomagnetic field is weak, such as during past geomagnetic excursions or reversals. Here, we model the impacts of an extreme SPE under different geomagnetic field strengths, focusing on changes in atmospheric chemistry and surface radiation using the atmosphere-ocean-chemistry-climate model SOCOL3-MPIOM and the radiation transfer model LibRadtran. Under current geomagnetic conditions, an extreme SPE would increase NOx concentrations in the polar stratosphere and mesosphere, causing reductions in extratropical stratospheric ozone lasting for about a year. In contrast, with no geomagnetic field, there would be a substantial increase in NOx throughout the entire atmosphere, resulting in severe stratospheric ozone depletion for several years. The resulting ground-level ultraviolet (UV) radiation would remain elevated for up to 6 y, leading to increases in UV index up to 20 to 25% and solar-induced DNA damage rates by 40 to 50%. The potential evolutionary impacts of past extreme SPEs remain an important question, while the risks they pose to human health in modern conditions continue to be underestimated. [ABSTRACT FROM AUTHOR]

The Equatorial Electrojet (EEJ) is one of the important near‐earth space weather phenomena which exhibits significant diurnal, seasonal and solar activity variations. This paper investigates the EEJ variations at diurnal, seasonal and solar cycle time scales from the Indian sector and portrays a new empirical EEJ field model developed using the observations spanning over nearly two solar cycles. The Method of Naturally Orthogonal Components (MNOC), also known as Principal Component Analysis (PCA), was employed to extract the dominant patterns of principal diurnal, semi‐diurnal, and ter‐diurnal components contributing to the EEJ variation. The amplitudes of these diurnal, semi‐diurnal, and ter‐diurnal components in EEJ are found to vary significantly with the season and solar activity. The seasonal and solar activity dependencies of these principal components are modeled using suitable bimodal distribution functions. Finally, the empirical model for EEJ field was built by combining the principal components with their corresponding modeled amplitudes. This model accurately reproduces the diurnal, seasonal and solar activity variations of EEJ. The modeled monthly mean variations of EEJ field at ground exhibit excellent correlation of 0.96 with the observations with the root mean square error <5 nT. It also successfully captures the seasonal and solar activity variations of Counter Electrojet (CEJ). Finally, this model named "Indian Equatorial Electrojet (IEEJ) Model" is made publicly available for interested scientific users (https://iigm.res.in/system/files/IEEJ_model.html). Plain Language Summary: The equatorial electrojet (EEJ) is an intense current jet flowing in the upper atmosphere around 100 km. This is a unique phenomenon that occurs at only a few kilometers in height (e.g., 105–110 km) and with a horizontal (North‐South) width of a few hundred kilometers (e.g., ∼600 km) centered on the geomagnetic equator. This important geophysical phenomenon gives more insights into the equatorial ionospheric electrodynamical processes that have various impacts on satellite orbital dynamics, Global Positioning Systems and other satellite communication links, electrical power grids, etc. This study develops a new empirical model to predict the diurnal, seasonal, and solar activity variations in the intensity of this unique current system over the Indian longitude sector. Key Points: An empirical Equatorial Electrojet (EEJ) field model was developed using nearly two solar cycles of EEJ observations from the Indian sectorThe principal diurnal, semi‐diurnal, and ter‐diurnal components in the EEJ are modeled using suitable analytical functionsThis model can very accurately predict the diurnal, seasonal, and solar activity variations of monthly mean EEJ and CEJ fields at ground [ABSTRACT FROM AUTHOR]

It is very important to carry out effective safety inspections on suppression rigging because of the bad service environment of suppression rigging: marine environments. In this paper, the multi-parameter simulation method in ANSYS and ANSYS Electronics Suite simulation software is used to simulate the effect of geomagnetic fields on the magnetic induction intensity of defective pressed rigging under the variable stress in marine environments. The results of the ANSYS simulation and geomagnetic flaw detection equipment are verified. The simulation results show that, according to the multi-parameter simulation results of ANSYS and ANSYS Electronics Suite simulation software, it can be found that, under the action of transverse force, the internal stress of the pressed rigging will affect the magnetic field around pressed rigging with defects. With an increase in internal stress in the range of 0~20 MPa, the magnetic induction intensity increases to 0.55 A/m, and with an increase in internal stress in the range of 20~150 MPa, the magnetic induction intensity decreases to 0.06 A/m. From the use of a force magnetic coupling analysis method, it can be obtained, under the lateral force of the defects in suppressing rigging, that magnetic flux leakage signals decrease with an increase in the rigging's radial distance. The experiment results show that the difference between the peak and trough of the magnetic induction intensity at the pressed rigging defect calculated by the ANSYS simulation is very consistent with the results measured by the geomagnetic flaw detection equipment. [ABSTRACT FROM AUTHOR]

There are growing concerns about the effect of solar flares on the ionosphere, mainly due to possible deterioration or damage to our communication and navigation satellite systems. On 3 July 2021, and 28 October 2021, there were solar flares (SFs) classified as X1.59 and X1.0, respectively. These two SFs were the only ones of X‐class that occurred during the last low solar activity (LSA:2018–2021). Data from magnetometers and Global Positioning System (GPS)—Total Electron Content (TEC) are used to investigate the spatial‐temporal electrodynamics of the ionosphere from pole‐to‐pole in the American sector. Employing ∆H and vertical TEC, along with the ROT (rate of change of VTEC) parameter. Rapidly ∆H disturbances closely follow the X‐ray variation and the ∆H valleys and peaks are well‐synchronized during the SFs, indicating that they are linked. Major disturbances in the ∆H are noticed in the mid‐low‐equatorial latitudes. However, minor disturbances were seen at high latitudes. Also, |ROT| is a good indicator of the electron density changes during the SFs, especially when the X‐ray intensity rises to the peak. Plain Language Summary: There are growing concerns about the effect of solar flares on the ionosphere, mainly due to possible deterioration or damage to our communication and navigation satellite systems. This kind of space weather event known as solar flare, releases energy in the form of radiation in the entire electromagnetic spectrum. However, the UV, EUV, and X‐ray radiation burst penetrates deeper into the Earth's atmosphere and is absorbed in the D and E regions (lower ionosphere) and F‐region. In this investigation the ionospheric disturbances are investigated, from pole‐to‐pole, using a magnetometer and GPS‐TEC networks. Key Points: The primary objective of this paper is to investigate the ionospheric response to solar flares across the entire latitudinal rangeThe ∆H exhibited synchronized peaks and valleys, during SF. The ROT is the most effective parameter to study electron density disturbancesThe methodology employed in this study involves the calculation and analysis of ∆H, VTEC, and ROT (Rate of TEC change) [ABSTRACT FROM AUTHOR]

Abstract Machine learning (ML) as a tool is rapidly emerging in various branches of contemporary geophysical research. To date, however, rarely has it been applied specifically for the study of Earth’s internal magnetic field and the geodynamo. Prevailing methods currently used in inferring the characteristic properties and the probable time evolution of the geodynamo are mostly based on reduced representations of magnetohydrodynamics (MHD). This study introduces a new inference method, referred to as Current Loop-based UNet Model Segmentation Inference (CLUMSI). Its long-term goal focuses on uncovering concentrations of electric current densities inside the core as the direct sources of the magnetic field itself, rather than computing the fluid motion using MHD. CLUMSI relies on simplified models in which equivalent current loops represent electric current systems emerging in turbulent geodynamo simulations. Various configurations of such loop models are utilized to produce synthetic magnetic field and secular variation (SV) maps computed at the core–mantle boundary (CMB). The resulting maps are then presented as training samples to an image-processing neural network designed specifically for solving image segmentation problems. This network essentially learns to infer the parameters and configuration of the loops in each model based on the corresponding CMB maps. In addition, with the help of the Domain Adversarial Training of Neural Networks (DANN) method during training, historical geomagnetic field data could also be considered alongside the synthetic samples. This implementation can increase the likelihood that a network trained primarily on synthetic data will appropriately handle real inputs. Our results focus mainly on the method's feasibility when applied to synthetic data and the quality of these inferences. A single evaluation of the trained network can recover the overall distribution of loop parameters with reasonable accuracy. To better represent conditions in the outer core, the study also proposes a computationally feasible process to account for magnetic diffusion and the corresponding induced currents in the loop models. However, the quality of the reconstruction of magnetic field properties is compromised by occasional poor inferences, and an inability to recover realistic SV. Graphical Abstract

Living organisms have evolved within the natural electromagnetic fields (EMFs) of the earth which comprise the global atmospheric electrical circuit, Schumann resonances (SRs) and the geomagnetic field. Research suggests that the circadian rhythm, which controls several physiological functions in the human body, can be influenced by light but also by the earth's EMFs. Cyclic solar disturbances, including sunspots and seasonal weakening of the geomagnetic field, can affect human health, possibly by disrupting the circadian rhythm and downstream physiological functions. Severe disruption of the circadian rhythm increases inflammation which can induce fatigue, fever and flu-like symptoms in a fraction of the population and worsen existing symptoms in old and diseased individuals, leading to periodic spikes of infectious and chronic diseases. Possible mechanisms underlying sensing of the earth's EMFs involve entrainment via electrons and electromagnetic waves, light-dependent radical pair formation in retina cryptochromes, and paramagnetic magnetite nanoparticles. Factors such as electromagnetic pollution from wireless devices, base antennas and low orbit internet satellites, shielding by non-conductive materials used in shoes and buildings, and local geomagnetic anomalies may also affect sensing of the earth's EMFs by the human body and contribute to circadian rhythm disruption and disease development.

When a magnetic storm hits a power transmission system, quasi-stationary geomagnetically induced currents (GIC) are generated in the high-voltage part of the system. These currents cause semi-saturation of the magnetic circuits of power transformers, which induces current overload in their high-voltage windings and subsequently thermal overload, which can lead to system failures. This rather complex phenomenon was described in [11] by a system of nonlinear differential equations and subsequently solved. This very challenging method is replaced in the present work by a simple approach. It allows not only predicting the imminent danger of system collapse, but gives transformer designers valuable information on how they can counteract this danger. [ABSTRACT FROM AUTHOR]

Interplanetary (IP) shocks are one of the dominant solar wind structures that can significantly impact the Geospace when impinge on the Earth's magnetosphere. IP shocks severely distort the magnetosphere and induce dramatic changes in the magnetospheric currents, often leading to large disturbances in the geomagnetic field. Sudden enhancements in the solar wind dynamic pressure (PDyn) during IP shocks cause enhanced high‐latitude convection electric fields which penetrate promptly to equatorial latitudes. In response, the equatorial electrojet (EEJ) current exhibits sharp changes of magnitudes primarily controlled by the change in PDyn and the local time. In this paper, we further investigated the influence of shock impact angle on the EEJ response to a large number (306) of IP shocks that occurred during 2001–2021. The results consistently show that the EEJ exhibits a heightened response to the shocks that head‐on impact the magnetosphere (frontal shocks) than those with inclined impact (inclined shocks). The greater EEJ response during the frontal shocks could be due to a more intensified high‐latitude convection electric field resulting from the symmetric compression of the magnetosphere. Finally, an existing empirical relation involving PDyn and local time is improved by including the effects of impact angle, which can quantitatively better predict the EEJ response to IP shocks. Plain Language Summary: Solar Wind, a continuous stream of high‐energy particles emanating from the Sun, is ubiquitous in interplanetary (IP) space. In unison, the energetic and/or transient eruptions on the Sun often release bursts of fast solar wind. When this fast solar wind interacts with the ambient solar wind in the IP space, a shock front is formed known as IP shock. These IP shocks (if Earth‐directed) can impinge on the Earth's magnetosphere and transfer tremendous amounts of energy and momentum. As a result, the Earth's magnetic field is often severely disturbed. Severe geomagnetic disturbances are known to cause a myriad of space weather effects from the loss of satellites in space to damage of electrical power grids and transmission lines on ground. Historically, geomagnetic field disturbances are known to be more cataclysmic at high latitudes and lessen at latitudes below the auroral region. However, these disturbances again dramatically enhance at equatorial latitudes due to a unique ionospheric current system, known as equatorial electrojet (EEJ). This study provides new insights into the significant role of angle of shock impacting the magnetosphere and the resultant disturbances in EEJ. This study also derives an empirical relation to accurately estimate the EEJ disturbances during IP shocks. Key Points: The angle of interplanetary (IP) shock impact on the magnetosphere plays a significant role in controlling the equatorial electrojet (EEJ) responseThe magnitude of EEJ change due to the impact of frontal IP shocks is significantly larger than that for the inclined shocksAn improved empirical relation including the effects of impact angle is derived which provide better estimates of EEJ responses to IP shocks [ABSTRACT FROM AUTHOR]

The SEM‐2 (Space Environment Monitor‐2) instrument embedded on the NOAA‐15 Low Earth Orbit satellite provides measurements of trapped protons in the Van Allen inner belt from 1998 to nowadays. This continuous set of measurements enables us to study the dynamics of the South Atlantic Anomaly (SAA) over more than two solar cycles, particularly, its temporal evolution. We observe that the area of the SAA is anti‐correlated with the solar activity. Two physical processes explain this anticorrelation. First, the more the Sun is active the more it disables the cosmic rays to reach the Earth's magnetosphere and fill in the inner radiation belt with protons. Then, when the Sun is more active, the upper atmosphere is warmer and therefore absorbs more protons from the radiation belt. Then, we investigate the protons flux centroid of the SAA. The temporal evolution of its position, latitude and, longitude is studied over the same time interval (1998–2022). We notice that the latitude of the centroid is also anti‐correlated with the solar activity whereas the longitude seems absolutely independent. The temporal evolution of the position of the centroid shows a drift of the SAA. Indeed from 1998 to 2022 the SAA drifted of about 7° West. The SEM‐2 instrument measures flux for protons of different energies (16, 36, 70, and, 140 MeV). For each energy, the SAA dynamic has a similar trend but with different values. These differences are investigated and the results are discussed. Key Points: The SAA is studied from proton flux measurements values in the inner radiation belt collected during the 1998–2022 period by the SEM‐2 instrument embedded on the NOAA‐15 satelliteThe SAA drifts globally Northward with an anticorrelation of its latitude with the solar activity and 7° Westward over a 24‐years periodThe higher the energy of the protons, the farther north and west the SAA shifts [ABSTRACT FROM AUTHOR]

Machine learning (ML) as a tool is rapidly emerging in various branches of contemporary geophysical research. To date, however, rarely has it been applied specifically for the study of Earth's internal magnetic field and the geodynamo. Prevailing methods currently used in inferring the characteristic properties and the probable time evolution of the geodynamo are mostly based on reduced representations of magnetohydrodynamics (MHD). This study introduces a new inference method, referred to as Current Loop-based UNet Model Segmentation Inference (CLUMSI). Its long-term goal focuses on uncovering concentrations of electric current densities inside the core as the direct sources of the magnetic field itself, rather than computing the fluid motion using MHD. CLUMSI relies on simplified models in which equivalent current loops represent electric current systems emerging in turbulent geodynamo simulations. Various configurations of such loop models are utilized to produce synthetic magnetic field and secular variation (SV) maps computed at the core–mantle boundary (CMB). The resulting maps are then presented as training samples to an image-processing neural network designed specifically for solving image segmentation problems. This network essentially learns to infer the parameters and configuration of the loops in each model based on the corresponding CMB maps. In addition, with the help of the Domain Adversarial Training of Neural Networks (DANN) method during training, historical geomagnetic field data could also be considered alongside the synthetic samples. This implementation can increase the likelihood that a network trained primarily on synthetic data will appropriately handle real inputs. Our results focus mainly on the method's feasibility when applied to synthetic data and the quality of these inferences. A single evaluation of the trained network can recover the overall distribution of loop parameters with reasonable accuracy. To better represent conditions in the outer core, the study also proposes a computationally feasible process to account for magnetic diffusion and the corresponding induced currents in the loop models. However, the quality of the reconstruction of magnetic field properties is compromised by occasional poor inferences, and an inability to recover realistic SV. [ABSTRACT FROM AUTHOR]

A typical magnetometer-based measurement-while-drilling (MWD) system determines the azimuth of the bottom hole assembly during the drilling process by employing triaxial accelerometers and magnetometers. The geomagnetic azimuth solution is susceptible to magnetic interference, especially strong magnetic interference and so a rotary norm constraint filtering (RNCF) method for azimuth estimation, designed to support a gyroscope-aided magnetometer-based MWD system, is proposed. First, a new magnetic dynamical system, one whose output is observed by the magnetometers triad, is designed based on the Coriolis equation of the desired geomagnetic vector. Second, given that the norm of the non-interfered geomagnetic vector can be approximated as a constant during a short-term drilling process, a norm constraint procedure is introduced to the Kalman filter. This is achieved by the normalization of the geomagnetic part of the state vector of the dynamical system and is undertaken in order to obtain a precise geomagnetic component. Simulation and actual drilling experiments show that the proposed RNCF method can effectively improve the azimuth measurement precision with 98.5% over the typical geomagnetic solution and 37.1% over the KF in a RMSE sense when being strong magnetic interference environment. [ABSTRACT FROM AUTHOR]

The disturbances in the lower ionosphere during the strong earthquake in Türkiye and Syria and its strongest aftershock on February 6, 2023, are analyzed using data from ground-based magnetometers. The observation points are located at distances 700 to 1600 km from the epicenter of the seismic event. As a characteristic of the ionospheric response to these events, variations in the magnetic field have been analyzed at the İznik, Grocka, Panagjurishte, and Surlari magnetic observatories. Earthquake epicenter is known to be a source of both seismic Rayleigh waves and atmospheric acoustic-gravity waves. Using the difference in velocities, at which these waves propagate from the epicenter, and their spectral composition, we found the ionospheric responses to the events that are interpreted quite well in terms of acoustic waves (produced by seismic Rayleigh wave) and atmospheric internal gravity waves generated in the earthquake epicenter. [ABSTRACT FROM AUTHOR]

Gujarat region (India) was struck by an earthquake of magnitude 5.3 on June 14, 2020 at 14:43 UTC near Bhachau city in Kachchh district in the state of Gujarat, with a depth of 20 km at the epicentre of 23.38° N, 70.36° E. In order to study the earthquake precursors for this event, data from the Induction Coil Magnetometer (LEMI-30) installed at the Badargadh Multi-Parameter Geophysical Observatory (MPGO) was analyzed for the period from January 1 to June 16, 2020. This station is located ~20 km from the epicentre of this earthquake. We observed that a clear geomagnetic burst was identified in the raw data of the Bx and By components in the LEMI-30 data before this earthquake. Geomagnetic amplitude bursts were identified 6 to 18 days and 2 days before this earthquake with a frequency of 0.01 to 0.02 Hz. Polarization ratio (PR) analysis revealed an anomalous signal on June 11, 2020 with PR values increasing to 1.4. The planetary index (Kp) and disturbance storm time index (Dst) due to the Sun‒Earth interaction are also very low (Kp = 0.3 and Dst = –6 nT) from June 10 to 16, 2020. In order to understand the dynamics of seismic processes, fractal dimensional analysis is also applied to magnetic data. Fractal dimension values also corroborate with the results of PR analysis, which showed a similar anomaly on June 11, 2020. The ULF geomagnetic data was further analyzed by applying the band-pass filtered data instead of the raw data in the period range from 10 to 45 seconds and derived the Z/X amplitude ratio in the Pc3 band. We found an upward trend and a downward trend from June 10, 2020. Enhanced polarization ratios were detected in the reconstructed components using the EMD technique which are linked to the current earthquake. It has been clearly demonstrated that the EMD method can be used to isolate noise and thus improve the identification of simultaneous short-term geomagnetic variations/anomalies. Therefore, in our study, we have clearly differentiated their origin, whether external (the Sun‒Earth interactions) or internal (local changes in conductivity in the area of the preparation). [ABSTRACT FROM AUTHOR]

Using the Thermosphere-Ionosphere-Electrodynamic General Circulation Model (TIEGCM), a comparison of the ionospheric total electron content (TEC) between the South Atlantic anomaly (SAA) and the Indian Ocean (IO) at solar maximum is performed in this study. The results show that the average total electron content in the SAA is greater than that in the Indian Ocean in general. In order to further analyze the difference between the two regions, the empirical orthogonal function (EOF) are used to investigate the temporal and spatial characteristics of TEC. The empirical orthogonal function method separate part of the global four-peak structure (an equatorial ionization anomaly structure, distributed in Southeast Asia, South America, Africa, and central Pacific) and spatial variations in both regions. Moreover, the first mode of EOF shows the different distribution of Equatorial ionization anomaly in South America and central Pacific caused by deviation of geomagnetic field and tides between two regions, and the enhancement of TEC in SAA region at dusk is emphasized, but the enhancement of TEC in IO region at dawn is emphasized. The second mode performs the distribution of EIA in Africa related to solar radiation and E χ B drift. The third mode indicates the similar spatiotemporal variations from the geomagnetic field. Besides, the correlation between TEC and Dst in two regions indicate that there are some deficiencies in simulation to the specificity of SAA, and the deficiencies are likely caused by the model's inaccurate simulation of the magnetic field and particle deposition in the SAA region. [ABSTRACT FROM AUTHOR]

This paper represents the equilibrium positions and stability of two artificial satellites connected by light, flexible, and elastic long tethers under the combined effect of several classical perturbative forces in an elliptical orbit. The tether may be conducting or non-conducting. In our problem, it is taken as non-conducting in nature. We have treated the problem by taking five perturbative forces on the system simultaneously. Three perturbations exist due to the influences of the earth, namely geomagnetic fields, shadows, and oblateness. The other perturbations are due to the elasticity of the cable and solar light pressure. The effect of air resistance is neglected, considering the satellites as high-altitude satellites. To determine the stability of the satellites, we have used the Lyapunov method. The dynamical behaviors of the satellites are represented by differential equations. Based on analytical analysis of the differential equations of motion, we get the equilibrium positions of the system concerned in elliptical orbit. Lyapunov method gives the equilibrium position as unstable as expected. [ABSTRACT FROM AUTHOR]

The geomagnetic field is generated by dynamo processes in the Earth's core. This process is supported by the cooling of the planet and the growth of the solid core. It is known that the magnetic field existed long before the appearance of the solid core, although according to available estimates and calculations, this could not have happened. Moreover, according to some models, thermal conductivity in the Earth's core may be three times higher than generally accepted values. In this case, the magnitude of the convective heat flow decreases and the generation of the magnetic field stops. In the above-mentioned models it was assumed that the magnitude of the heat flow at the core – mantle boundary over the entire existence of the Earth linearly decreased by only 15–20 %. The latter is a rough guess. Significantly large changes in heat flow are predicted by models of mantle cooling, in which the growth of convective heat flow in ancient times occurs due to a decrease in the viscosity of the mantle with an increase in the temperature of the substance. Below we consider a model of the cooling of the Earth with a threefold value of the thermal conductivity of the core. It is shown that the use of a combined model of core and mantle cooling makes it possible to significantly increase the heat flow at the core – mantle boundary in ancient times. To slow down the growth of the solid core, a subadiabatic layer is included in the model. As a result, the size of the solid core in the model satisfies seismological observations. The model allows us to obtain a sufficient amount of energy to generate a geomagnetic field, starting from the moment the liquid core appeared and to the present. The appearance of a solid core 2.4 billion years ago, which does not lead to sharp changes in heat flow in the model, is consistent with paleomagnetic observations that do not record changes in the behavior of the magnetic field. The model does not exclude the existence of a multipole magnetic field at the initial stage.

Life on Earth evolved to accommodate the biochemical and biophysical boundary conditions of the planet millions of years ago. The former includes nutrients, water, and the ability to synthesize other needed chemicals. The latter includes the 1 g gravity of the planet, radiation, and the geomagnetic field (GMF) of the planet. How complex life forms have accommodated the GMF is not known in detail, considering that Homo sapiens evolved a neurological system, a neuromuscular system, and a cardiovascular system that developed electromagnetic fields as part of their functioning. Therefore, all of these could be impacted by magnetic fields. In addition, many proteins and physiologic processes utilize iron ions, which exhibit magnetic properties. Thus, complex organisms, such as humans, generate magnetic fields, contain significant quantities of iron ions, and respond to exogenous static and electromagnetic fields. Given the current body of literature, it remains somewhat unclear if Homo sapiens use exogenous magnetic fields to regulate function and what can happen if the boundary condition of the GMF no longer exerts an effect. Proposed deep space flights to destinations such as Mars will provide some insights, as space flight could not have been anticipated by evolution. The results of such space flight “experiments” will provide new insights into the role of magnetic fields on human functioning. This review will discuss the literature regarding the involvement of magnetic fields in various normal and disturbed processes in humans while on Earth and then further discuss potential outcomes when the GMF is no longer present to impact host systems, as well as the limitations in the current knowledge. The GMF has been present throughout evolution, but many details of its role in human functioning remain to be elucidated, and how humans have adapted to such fields in order to develop and retain function remains to be elucidated. Why this understudied area has not received the attention required to elucidate the critical information remains a conundrum for both health professionals and those embarking on space flight. However, proposed deep space flights to destinations such as Mars may provide the environments to test and assess the potential roles of magnetic fields in human functioning.

• Formation of low magnetic field region (dent) in Earth's magnetosphere during intense storm. • Altitude and mirror points of charged particles get affected by magnetic field hump and dent. • The dent in magnetic field is formed closer to the Earth as strength of ring current increases. The development of the ring current through a westward circulation of energetic ions around the Earth in the low latitude region during geomagnetic storms has been known to us for the past several decades. The symmetric part of the ring current exists in the form of a ring around the Earth at a distance of ≈ 3–7 R e from the center of the Earth. The location and strength of the ring current is mainly controlled by the interplanetary solar wind conditions. The presence of such external current forms the additional mini magnetic dipole in the vicinity of the Earth's space, which eventually affects the geomagnetic field configuration. The magnetic field produced due to the ring current opposes the geomagnetic field inside and adds to the geomagnetic field outside the location of the ring current. This scenario has been modelled in this paper by using a circular loop of uniform current around the Earth to represent the ring current flow around the Earth. The aim of the present study is to understand the overall changes in the magnetic field and its influence on the radiation belt energetic (MeV range) electrons and protons during a geomagnetic storm. The model calculations suggest the formation of low and high magnetic field regions (here referred to as dent and hump) in the Earth's magnetosphere due to intense westward ring current. The size and position of these low and high magnetic field regions are controlled by the strength and location of the ring current. It is found that both the altitudinal reach and mirror point of the bouncing-drifting radiation belt energetic particles are significantly affected by the presence of the dent and the hump in the magnetic field driven by the ring current. The decrease in ground magnetic field of 1700 nT or more, which is similar to the geomagnetic field variation observed during the historic Carrington event, is possible with the peak ring current strength of 20–30 MA situated at a distance of 2 R e or less from the center of the Earth. [ABSTRACT FROM AUTHOR]

This study creates a three-dimensional surface spline (3DSS) model of mainland China based on surface and CHAMP satellite observations. Through this model, the magnetic field analyses of domestic plateau (Qinghai-Tibet Plateau 28°N–38°N, 78°E–102°E), plain (middle and lower reaches of Yangtze River Plain 27°N–34°N, 111°E–122°E), and marine (parts of the East and South China Seas 16°N–30°N, 123°E–136°E) areas have been investigated. Single models of plateau and plain have also been created. To compare and verify results, the corresponding two-dimensional (2DTY) and three-dimensional (3DTY) Taylor polynomial models have been derived. Issues such as the removal of disturbing geomagnetic fields, the data gap between surface and satellite level, and boundary effect are all seriously considered. With an aim to evaluate the resulting model, some randomly selected points are not join the modeling, by which we thereby inspected the results in terms of residuals, change rate absolutes, and Root Mean Square Error (RMSE). Results show that except component Y, the change rate absolutes of other components are less than 1% both in domestic and single models, which means that the modeling result of 3DSS is better than the other two models. Plateau and plain 3DSS models reflect the fine distribution of the magnetic field after comparison with domestic distribution. The 3DSS model fits the plateau best, followed by the plain, while the worst fit is in the marine area. This means that the modeling precision depends mainly on the number and distribution of measuring points. [ABSTRACT FROM AUTHOR]

Life on Earth evolved to accommodate the biochemical and biophysical boundary conditions of the planet millions of years ago. The former includes nutrients, water, and the ability to synthesize other needed chemicals. The latter includes the 1 g gravity of the planet, radiation, and the geomagnetic field (GMF) of the planet. How complex life forms have accommodated the GMF is not known in detail, considering that Homo sapiens evolved a neurological system, a neuromuscular system, and a cardiovascular system that developed electromagnetic fields as part of their functioning. Therefore, all of these could be impacted by magnetic fields. In addition, many proteins and physiologic processes utilize iron ions, which exhibit magnetic properties. Thus, complex organisms, such as humans, generate magnetic fields, contain significant quantities of iron ions, and respond to exogenous static and electromagnetic fields. Given the current body of literature, it remains somewhat unclear if Homo sapiens use exogenous magnetic fields to regulate function and what can happen if the boundary condition of the GMF no longer exerts an effect. Proposed deep space flights to destinations such as Mars will provide some insights, as space flight could not have been anticipated by evolution. The results of such space flight "experiments" will provide new insights into the role of magnetic fields on human functioning. This review will discuss the literature regarding the involvement of magnetic fields in various normal and disturbed processes in humans while on Earth and then further discuss potential outcomes when the GMF is no longer present to impact host systems, as well as the limitations in the current knowledge. The GMF has been present throughout evolution, but many details of its role in human functioning remain to be elucidated, and how humans have adapted to such fields in order to develop and retain function remains to be elucidated. Why this understudied area has not received the attention required to elucidate the critical information remains a conundrum for both health professionals and those embarking on space flight. However, proposed deep space flights to destinations such as Mars may provide the environments to test and assess the potential roles of magnetic fields in human functioning. [ABSTRACT FROM AUTHOR]

Based on Global Coupled Ionosphere‐Thermosphere‐Electrodynamics Model, the solution of the 3‐dimensional current in the ionospheric region, the equivalent sheet current and filed‐aligned current are examined. The simulation study enables a comprehensive analysis of the effect of the geomagnetic field configuration, especially the non‐dipole component and tilt angle, on the ionospheric electrodynamics phenomena. Different geomagnetic field configurations are specified in the present work, including realistic geomagnetic field (RGF), tilted dipole geomagnetic field (TDGF) and zero‐declination dipole geomagnetic field (ZDGF). Our simulation focuses on the seasonal variation of Sq current, primarily governed by annual and semi‐annual variation. The modulation of the tilt angle of the geomagnetic field is globally distributed, whereas the modulation of the geomagnetic anomaly is localized. At mid‐latitudes, the annual mean and semi‐annual amplitudes of the Sq current are negatively correlated with the magnetic field strength, especially shown in geomagnetic anomaly area, while there is the opposite effect in the geomagnetic conjugate regions of the opposite hemispheres. The annual variation of Sq current system is more affected by the offset of the geomagnetic latitudes and geographical latitudes. The seasonal variation of the total Sq current is also modulated by the geomagnetic field. The annual mean, the annual and semi‐annual components of the total Sq current are negatively correlated with the magnetic field strength, while the annual variation is also controlled by the tilt angle of the geomagnetic field. The solar radiation affects the semi‐annual variation of the current more strongly than the annual variation. Plain Language Summary: Ionospheric currents and magnetic fields exert significant influences on energy and material transport within the ionosphere, playing a pivotal role in Earth's electromagnetic environment, which is the primary focus of ionospheric research. To investigate the impact of the geomagnetic field on the ionospheric current system, we employ a theoretical model (GCITEM) for simulation work. In this simulation, we consider both the realistic geomagnetic field configuration and two hypothetical idealized configurations of the geomagnetic field: one excluding non‐dipole terms and the other further aligning the geomagnetic axis with Earth's spin axis. The analysis of the longitude and the seasonal variation of the simulated currents under realistic magnetic field conditions has been validated through previous observation results. In comparison to simulation results obtained under hypothetical configurations, we discern and analyze the modulation and mechanism of non‐dipole terms and the tilt angle of geomagnetic field on the variability of the ionospheric current system, which are discussed in detail within this paper. This study facilitates the analysis and prediction of long‐term changes in the geomagnetic field's effects on ionospheric current generation and the impact on space's electromagnetic environment. Key Points: The geomagnetic field intensity exerts a significant influence on the Sq currents and exhibits a negative correlation with Sq currentThe annual mean and annual variation amplitude of Sq current are positively correlated with the geomagnetic anomaly at conjugate pointsThe tilt angle of the geomagnetic field affects the annual variation of Sq current globally, but hardly effects the semiannual variation [ABSTRACT FROM AUTHOR]

The paleodirection and paleointensity of the geomagnetic field are determined from seven andesibasalt–basalt samples of three lava flows (L1–L3) from the Avachinskii (Avacha) volcano. Based on the sample from the recent lava flow TFE-50 (Tolbachik Fissure Eruption), the reliability of the Thellier–Coe method for geomagnetic field paleointensity determination is demonstrated: the deviation of the calculated Han from the IGRF12 values is at most 3% with a quality factor q > 13. The age of lava flows L1–L3 is refined using paleomagnetic data. Flows L1, L2 of the Molodoi Cone were formed in 1827 and 300–600 years ago, respectively, and the age of flow L3 at the crest of the somma is determined at 30–32 ka, which agrees with the known age estimate of the debris avalanche associated with the catastrophic destruction of the Avachinskii volcano 29 900 ± 37 900 14C years ago. [ABSTRACT FROM AUTHOR]

With the rapid development of mobile Internet, the demand for Indoor Location-Based Service (ILBS) keeps rising. Geomagnetic field fingerprinting-based positioning scheme, with low cost, high accuracy and good stability, has gradually earned the attention of researchers. There are many problems in the existing indoor localisation researches based on geomagnetic fingerprint recognition, such as heavy workload of fingerprint collection, insufficient positioning accuracy, high walking cost of positioning and long positioning delay. Therefore, a localisation system named DCGIL is proposed in this thesis. In DCGIL, a segmentation length estimation algorithm of geomagnetic fingerprint sequence is proposed to evaluate the minimum segmentation length, the shortest walking distance. Then, through an overlapping fingerprint segmentation method, the gap between coordinate points and the cost of fingerprint matching are reduced. Further, dilated convolutional neural networks is utilised for segmented fingerprint classification, which could improve the accuracy of fingerprint classification compared with the existing classification methods. Finally, DCGIL utilises the sliding window to align and match the segmented fingerprint. Experiments show that the localisation accuracy reached 1.21 metres at 3.8 m shortest walking distance derived from segmentation length estimation algorithm, which improved 28% compared to existing algorithms. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of human heart-rate synchronization with variations in the geomagnetic field (GMF) ("biogeophysical synchronization effect"). We analyzed 403 electrocardiogram (ECG) recordings of 100 or 120 min that were obtained in 2012–2023 from two middle-aged female volunteers in good health. The minute-value series of the GMF vector from the INTERMAGNET network was used. Each ECG recording was individually examined using cross-correlation and wavelet analysis. The findings from two separate experimental sets (306 recordings from Volunteer A and 97 from Volunteer B) displayed notable similarity in all aspects analyzed: (1) For both participants, the biogeophysical synchronization effect is observed in 40–53% of the recordings as a statistically significant (p < 0.0045) correlation between minute heart-rate (HR) time-series values and at least one of the horizontal components of the GMF, with a time shift between values of [−5, +5] min. (2) Wavelet analysis indicates that the spectra of the HR series and at least one GMF component exhibit similarity in 58–61% of cases. (3) The synchronization is most evident within the period range between 8–13 min. The probability of the synchronization effect manifestation was independent of the geomagnetic activity (GMA) level, which was recorded during the observations. [ABSTRACT FROM AUTHOR]

The article describes the sources of geomagnetic data, the reduction of geomagnetic data for the territory of Latvia to the epoch 2021.5, the history of previous magnetic observations in Latvia, the information available in the State Geodetic Network database and the information available in the World Geomagnetism Data Centre. The sequence of absolute measurements is described in detail. To visualise the changes in the magnetic declination value in the territory of Latvia, a 2021.5 year declination fluctuation has been created using ArcGIS Pro. The declination values in Latvia range from 6.68° to 10°, the inclination values range from 71.089° to 72.245° and the total magnetic field values from 51100 nT to 52594 nT. The values obtained for the magnetic field components refer to a magnetically clean environment, and there can be, and are, differences in the natural conditions in the Latvian territory, in natural anomalous locations and in locations with artificially high magnetic field noise (e.g. in cities, near railways, near high voltage lines, etc.). In the Latvian network, points have been selected in locations where the magnetic noise is minimal, as this is the technological process for building such stations. Magnetic observatories are even stricter, so the data coming from the observatories reflect the natural magnetic field without the influence of magnetic anomalies. The reduced magnetic field values and their representation on a map can be used for aeronautical navigation, military applications, identification of local magnetic anomaly sites or search for magnetically clean environments. [ABSTRACT FROM AUTHOR]

The use of a magnetic compass in paleomagnetic studies of highly magnetic rocks (for instance, basalts) can lead to large errors in the orientation of paleomagnetic samples. On the other hand, alternative methods of orientation are relatively time-consuming, and in the case of using a solar compass, they also require sunny weather – a condition that is rarely met, especially when sampling at high and subpolar latitudes. This often leads to the fact that researchers in their work rely on the results of magnetic compass measurements, while assuming that the resulting errors are of a random nature and, with sufficiently good statistics, are averaged. In this study, numerical modeling is performed, which allows us to verify this assumption and assess how much orientation errors associated with the use of a magnetic compass can affect the final results of paleomagnetic studies, such as determining the position of the paleomagnetic pole and the amplitude of ancient geomagnetic variations. As a result of the work performed , it is shown that: 1) the amplitudes of paleosecular variations and the positions of paleomagnetic poles are weakly sensitive to moderate and even relatively large errors in the orientation of paleomagnetic samples associated with the use of a magnetic compass; 2) very large errors in the orientation of samples lead to a significant increase in the within-site scatter of paleomagnetic directions, which makes it possible to detect and exclude the corresponding sites with a large (for instance >15°) value of the α95; 3) the influence of distortions associated with the use of a magnetic compass on the accuracy of determining the position of the paleomagnetic pole and the amplitude of ancient geomagnetic variations depends on latitude. At near-equatorial latitudes, this effect is maximal, at medium latitudes – minimal.

The article describes the sources of geomagnetic data, the reduction of geomagnetic data for the territory of Latvia to the epoch 2021.5, the history of previous magnetic observations in Latvia, the information available in the State Geodetic Network database and the information available in the World Geomagnetism Data Centre. The sequence of absolute measurements is described in detail. To visualise the changes in the magnetic declination value in the territory of Latvia, a 2021.5 year declination fluctuation has been created using ArcGIS Pro. The declination values in Latvia range from 6.68° to 10°, the inclination values range from 71.089° to 72.245° and the total magnetic field values from 51100 nT to 52594 nT. The values obtained for the magnetic field components refer to a magnetically clean environment, and there can be, and are, differences in the natural conditions in the Latvian territory, in natural anomalous locations and in locations with artificially high magnetic field noise (e.g. in cities, near railways, near high voltage lines, etc.). In the Latvian network, points have been selected in locations where the magnetic noise is minimal, as this is the technological process for building such stations. Magnetic observatories are even stricter, so the data coming from the observatories reflect the natural magnetic field without the influence of magnetic anomalies. The reduced magnetic field values and their representation on a map can be used for aeronautical navigation, military applications, identification of local magnetic anomaly sites or search for magnetically clean environments.

The paper aims at an experimental study of the mechanisms of long-distance high-frequency (HF) propagation and spatial and temporal variations of the ionospheric parameters during the first hours of a severe geomagnetic storm of April 23, 2023 by spatially separated measuring equipment located at the research vessel (RV) Noosfera, the Ukrainian Antarctic Akademik Vernadsky station (hereinafter Vernadsky), and the LOFAR observatory PL610 in Borowiec (Poland). High-frequency vertical and oblique sounding techniques of the ionosphere were used. Geospace measurements were carried out synchronously. During the first hours of the geomagnetic storm of April 23–24, 2023, unexpectedly well-correlated variations in the Doppler frequency shifts of HF signals emitted from Vernadsky were observed at the RV Noosfera and the PL610 station. Furthermore, variations in Doppler frequency shifts of HF signals strongly correlate with magnetic field records in Antarctica and Poland. Variations in the frequency of HF signal spectral components, distinguishable during storm conditions, are utilized to clarify the mechanism of long-distance HF propagation and estimate the vertical velocity of ionospheric layers. Signals of HF CHU time radio station (Canada) at 7850 and 14670 kHz were unexpectedly observed in all receiving sites. Most probably, the CHU station radio signals registered during the initial stage of the geomagnetic storm were scattered on the polar ovals’ ionospheric inhomogeneities and propagated further along the return (long arc of the great circle) paths. Redistribution of the ionospheric plasma during the geomagnetic storm leads to the formation of HF radio propagation channels absent under quiet conditions.

It is very important to carry out effective safety inspections on suppression rigging because of the bad service environment of suppression rigging: marine environments. In this paper, the multi-parameter simulation method in ANSYS and ANSYS Electronics Suite simulation software is used to simulate the effect of geomagnetic fields on the magnetic induction intensity of defective pressed rigging under the variable stress in marine environments. The results of the ANSYS simulation and geomagnetic flaw detection equipment are verified. The simulation results show that, according to the multi-parameter simulation results of ANSYS and ANSYS Electronics Suite simulation software, it can be found that, under the action of transverse force, the internal stress of the pressed rigging will affect the magnetic field around pressed rigging with defects. With an increase in internal stress in the range of 0~20 MPa, the magnetic induction intensity increases to 0.55 A/m, and with an increase in internal stress in the range of 20~150 MPa, the magnetic induction intensity decreases to 0.06 A/m. From the use of a force magnetic coupling analysis method, it can be obtained, under the lateral force of the defects in suppressing rigging, that magnetic flux leakage signals decrease with an increase in the rigging’s radial distance. The experiment results show that the difference between the peak and trough of the magnetic induction intensity at the pressed rigging defect calculated by the ANSYS simulation is very consistent with the results measured by the geomagnetic flaw detection equipment.