Hasil untuk "Geomagnetism"

Maximilian Arthus Schanner, Klaus Nielsen, Peter Bickerton et al.

This methodological communication paper details the creation and public reception of an audiovisual representation of the last geomagnetic excursion. Utilizing a global model of the Earth’s magnetic field, we developed a visualization and sonification designed to engage a broad audience with this extreme event in Earth’s history. The work reached over one million people online and sparked positive engagement, demonstrating the power of artistic interpretation in communicating complex scientific concepts. This project highlights the potential of innovative media formats for public outreach and science communication in the Earth sciences.

Yanyan Yang, Zhima Zeren, Gauthier Hulot et al.

Abstract This paper presents the second generation of the China Seismo-Electromagnetic Satellite (CSES) Global Geomagnetic Field Model (CGGM-2), specifically designed to derive candidate models for the fourteenth generation of the International Geomagnetic Reference Field (IGRF-14). To build this CGGM-2 model, we utilize more than six years of geomagnetic field data collected by the high-precision magnetometer (HPM) onboard CSES. The model is parametrized by expanding the internal field to spherical harmonic degree and order 45, now incorporating lithospheric contributions. This was not the case for the first generation CGGM model, which was limited to spherical harmonic degrees up to 15. We now also implement order six B-splines in time with one year knot spacing for degrees 1 to 13 to capture non-linear temporal variations in the core field, superseding the linear approximation used in CGGM. Despite a number of challenges, such as boom deformation on which the HPM is located (away from the star imager that provides attitude information) and high-latitude magnetic field platform disturbances, the CGGM-2 model succeeds at capturing the non-linear temporal variations of the geomagnetic field. In particular, the SV-2025-2030 candidate model derived from CGGM-2 performs particularly well among all 18 candidate models for IGRF-14. Candidate models derived from the CGGM-2 are also the only IGRF-14 candidate models using CSES data only and not directly relying on any ESA’s Swarm satellite data, thus providing useful candidate models to compare against all other IGRF candidate models. Our findings underscore the potential of CSES data for geomagnetic field modeling and the likely benefits of CSES’s revisiting capability for accurately capturing the main field's variations. It is expected that future data from the forthcoming companion CSES-02 mission will help improve the temporal–spatial resolution of the model and mitigate high-latitude magnetic platform disturbances. Graphical Abstract

Mingshu Zhao, Xiaoping Zeng, Yunfang Lin

We investigated turbulence-like behavior in the geomagnetic field using ground-based magnetic observatory data across China. Through analysis of spatial and temporal structure functions, we find power-law scaling consistent with Kolmogorov-like turbulence under extended self-similarity. We also identify significant correlations between vertical geomagnetic field variations and large earthquakes. The combination of turbulent characteristics with these correlations suggests a physical mechanism where solar activity provides energy that is transferred through turbulent processes to smaller scales, potentially contributing to earthquake triggering.

Paulramasamy Morthekai, Malika Singhal, Malika Singhal et al.

By 2019, a long brick platform with some structures was exposed when the Thamirabarani River, the southernmost river in the city of Thirunelveli, dried up. The civic society rejoiced at the discovery of the exposed structure as it was thought to be the palace of the first capital city of the Pandya dynasty, an ancient Tamil dynasty of southern India. Two bricks were removed from the structure to determine their ages using the luminescence dating method, and their geochemical composition was analyzed using the X-ray fluorescence method. The bricks were composed of mud that underwent intermediate silicate weathering. High values of anomalous fading rate were observed from both the fine-grain polymineral (9.5–10.5%.decade−1) and coarse-grain K-feldspar (15.5%.decade−1), and this could be attributed to the significant presence of sanidine phase of K-feldspar. The fading corrected luminescence ages (1430–1530 CE) based on the coarse grain K-feldspar of the bricks placed the structure historically in the period of the Vijayanagar Empire, where the Late Pandyas had some autonomy in the south. These age estimates could resolve the hypothesis that the structure was not made by the Early Pandyas (400 BCE−300 CE). This study also reports discrepant ages for coarse quartz grains samples (1,689 CE; ± 10 years, 1 σ) and two fine polymineral grains samples (1634 CE; ± 90 years and 1699 CE; ± 30 years) compared to the age of the coarse K-feldspar grains samples. This discrepancy requires further investigation.

D. Dwivedi, S. Yadav, K. Arora et al.

<p>The phases of development of Choutuppal magnetic observatory over the last 15 years have enabled the effects of the natural environment like groundwater changes and lightning activity on the magnetic data to be evaluated. A high-resolution survey of total field anomalies led to the construction of a 2D model of the shallow surface. Constrained by conductivity depth slices from previous electrical resistivity tomography and electrical vertical resistivity imaging surveys, the distribution of sandy regolith, saprolite and granitic layers in the shallow subsurface is delineated. The pattern of lightning strikes in a 10 km area around the observatory is correlated to modulations and disruptions in the magnetic data. The analysis as a whole provides information for selecting a location to install a secondary variometer room by taking into account topography, lightning effect, soil resistivity, low magnetic anomaly and distance from the recharge pond, which can produce continuous data of higher quality and consistency than at present.</p>

Beatriz Sánchez-Cano, Lina Z. Hadid, Sae Aizawa et al.

Abstract BepiColombo, the joint ESA/JAXA mission to Mercury, was launched in October 2018 and is scheduled to arrive at Mercury in November 2026 after an 8-year cruise. Like other planetary missions, its scientific objectives focus mostly on the nominal, orbiting phase of the mission. However, due to the long duration of the cruise phase covering distances between 1.2 and 0.3 AU, the BepiColombo mission has been able to outstandingly contribute to characterise the solar wind and transient events encountered by the spacecraft, as well as planetary environments during the flybys of Earth, Venus, and Mercury, and contribute to the characterisation of the space radiation environment in the inner Solar System and its evolution with solar activity. In this paper, we provide an overview of the cruise observations of BepiColombo, highlighting the most relevant science cases, with the aim of demonstrating the importance of planetary missions to perform cruise observations, to contribute to a broader understanding of Space Weather in the Solar System, and in turn, increase the scientific return of the mission. Graphical Abstract

Morgan Rivers, Łukasz G. Gajewski, David Denkenberger

Geomagnetic storms occurring due to sustained, high-speed solar winds are known to induce currents in power distribution networks. These geomagnetically induced currents (GICs) can cause high voltage transformers (HVT) to overheat, thus resulting in a catastrophic electricity loss event (CELE). Since significant portions of infrastructures around the world rely heavily on access to electric power, it is essential to estimate the risks associated with GICs on a global scale. We assemble multiple methodologies across various scientific disciplines to develop a framework assessing the probability of a severe geomagnetic storm causing a long-term, widespread power outage. Our model incorporates thermal models of HVT tie bar hot spots, historical geoelectric field estimates, and a global conductivity model to estimate the risk of long-term power outage for regions between -70 degrees and 80 degrees geomagnetic latitude due to transformer overheating failure. Assuming a uniform 33% HVT spare capacity, our analysis indicates that a 1 in 10,000 year storm would result in approximately 1% of the population in Europe and North America experiencing a long-term (months to years) electricity loss.

Shailaja Gandla, Bhavana Umrikar, Nyakno Jimmy George et al.

Abstract The hydrochemistry of groundwater in the Mann River basin, situated in eastern Maharashtra, was investigated through laboratory analysis with the aim of determining its suitability for consumption, agriculture, and industry. A total of 43 groundwater samples were collected from bore wells and dug wells across the basin for evaluation. Parameters including pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), and various cations and anions were examined in comparison with established standards set by the World Health Organization (WHO) and the Bureau of Indian Standards (BIS). Piper diagram analysis revealed that a significant portion of the samples fell into the CaMgHCO3 hydrochemical facies, while the Gibbs diagram suggested rock dominance in most samples. The drinking water quality index was calculated based on 11 parameters, with 52% of the samples falling into the excellent water category. The irrigation suitability assessment was based on parameters like the sodium adsorption ratio (SAR), percent sodium (%Na), and permeability index (PI), revealing that the majority of the samples were appropriate for irrigation. Moreover, assessments of industrial suitability rely on factors such as the Langelier saturation index (LSI) and Ryznar stability index (RSI) to estimate corrosion potential, with most samples showing a high propensity for corrosion and calcium carbonate deposition. Binary correlation effects were observed, suggesting that the presence of one physiochemical parameter could influence others. GIS-based maps were generated to precisely assess corrosion indices for effectively monitoring and managing water quality in the study area. This study is crucial as it evaluates the groundwater quality for its suitability for drinking, agriculture, and industry. It identifies groundwater’s chemical characteristics, irrigation potential, and corrosion risks, offering key insights for water management, ensuring safe consumption, and supporting agricultural and industrial applications.

Y. A. Engbers, D. Thallner, R. K. Bono et al.

Abstract Paleosecular variation analysis is a primary tool for characterizing ancient geomagnetic behavior and its evolution through time. This study presents a new high‐quality directional data set, paleosecular variation of the Paleogene (PSVP), with and without correction for serial correlation, compiled from 1,667 sites from 45 different localities from the Paleogene and late Cretaceous (84–23 Ma). The data set is used to study the variability, structure, and latitude dependence of the geomagnetic field during that period by varying selection criteria and PSV models. Modeled values for the equatorial virtual geomagnetic pole (VGP) dispersion have over‐lapping uncertainty intervals within their uncertainty bounds between 8.3° and 18.6° for the past 250 Ma. We investigate the suitability of two descriptive models of PSV, Model G‐style quadratic fits and covariant Giant Gaussian Process models, and find that both styles of model fail to satisfactorily reproduce the latitude dependent morphology of PSV, but suggest that estimates of the equatorial VGP dispersion may still robustly characterize aspects of Earth's long‐term field morphology. During this time where the PSV behavior has not changed substantially, the reversal frequency has varied widely. The lack of a clear relationship between PSV behavior and reversal frequency is not trivially explained in the context of published findings regarding numerical geodynamo simulations.

Amit Kumar, Danda Nagarjuna, M. Santosh et al.

The disintegration of the Columbia supercontinent during the late Paleoproterozoic generated major rift basins in the constituent continental fragments. The Kaladgi basin, located between the southern part of the Deccan volcanic province (DVP) and the northern part of the Dharwar craton, is a Columbia rift-related basin in southwestern India that preserves a complex history from initial fault-controlled mechanical subsidence during rifting, thermal subsidence along a collision zone, crustal thinning due to stretching and erosion associated with doming. The Paleoproterozoic basins worldwide show higher uranium concentration and many deposits are also established in the Purana basins of India. In the present study, the lithotectonic architecture of this basin using broadband magnetotelluric (∼320 Hz–3000 s) soundings in the western segment of the Kaladgi rift basin along two profiles. Two-dimensional (2-D) inversion of data using a 2-D nonlinear conjugate gradient algorithm along both profiles provides insights into the deeper structure of the basin. Our results reveal a thin sheet of Deccan volcanic, sedimentary successions belonging to the Badami and Bagalkot groups, and Proterozoic sediments from top to bottom beneath this basin. The crustal structure is highly heterogeneous and associated with deep-seated faults, and its thickness increases from the eastern Dharwar craton (∼30 km) to the western Dharwar craton (∼45 km). The crustal conductors are interpreted as mafic intrusions derived from the underplated basalts. The moderate conductive features may correspond to carbonate fluids trapped within the faults/fractures zone during basin initiation. The conductive features in the lower crust and the Moho are interpreted as fluids derived from underplated intrusions through plume impact. The NNW trending Chitradurga Suture Zone (CSZ) signature and the Bababudan-Nallur Shear (BNS) in the crust and upper mantle depth are imaged along both MT profiles. This study provides insights into the lithology and tectonic architecture of a long-lived rift basin involved in multiple tectonic events from the late Paleoproterozoic to the late Cretaceous.

Rongliang Chen, Youjun Deng, Yang Gao et al.

The presence of magnetized anomalies in the shell of the Earth interrupts its geomagnetic field. We consider the inverse problem of identifying the anomalies by monitoring the variation of the geomagnetic field. Motivated by the theoretical unique identifiability result in [5], we develop a novel numerical scheme of locating multiple magnetized anomalies. In our study, we do not assume that the source that generates the geomagnetic field, and the medium configurations of the Earth's core and the magnetized anomalies are a-priori known. The core of the reconstruction scheme is a novel imaging functional whose quantitative behaviours can be used to identify the anomalies. Both rigorous analysis and extensive numerical experiments are provided to verify the effectiveness and promising features of the proposed reconstruction scheme.

Simona Nitti, Tatiana Podladchikova, Stefan J. Hofmeister et al.

Coronal holes (CHs) are the source of high-speed streams (HSSs) in the solar wind, whose interaction with the slow solar wind creates corotating interaction regions (CIRs) in the heliosphere. Whenever the CIRs hit the Earth, they can cause geomagnetic storms. We develop a method to predict the strength of CIR/HSS-driven geomagnetic storms directly from solar observations using the CH areas and associated magnetic field polarity. First, we build a dataset comprising the properties of CHs on the Sun, the associated HSSs, CIRs, and orientation of the interplanetary magnetic field (IMF) at L1, and the strength of the associated geomagnetic storms by the geomagnetic indices Dst and Kp. Then, we predict the Dst and Kp indices using a Gaussian Process model, which accounts for the annual variation of the orientation of Earth's magnetic field axis. We demonstrate that the polarity of the IMF at L1 associated with CIRs is preserved in around 83% of cases when compared to the polarity of their CH sources. Testing our model over the period 2010-2020, we obtained a correlation coefficient between the predicted and observed Dst index of R = 0.63/0.73, and Kp index of R = 0.65/0.67, for HSSs having a polarity towards/away from the Sun. These findings demonstrate the possibility of predicting CIR/HSS-driven geomagnetic storms directly from solar observations and extending the forecasting lead time up to several days, which is relevant for enhancing space weather predictions.

Samuel Califf, Patrick Alken, Arnaud Chulliat et al.

Abstract The World Magnetic Model (WMM) is a geomagnetic main field model that is widely used for navigation by governments, industry and the general public. In recent years, the model has been derived using high accuracy magnetometer data from the Swarm mission. This study explores the possibility of developing future WMMs in the post-Swarm era using data from the Iridium satellite constellation. Iridium magnetometers are primarily used for attitude control, so they are not designed to produce the same level of accuracy as magnetic data from scientific missions. Iridium magnetometer errors range from 30 nT quantization to hundreds of nT errors due to spacecraft contamination and calibration uncertainty, whereas Swarm measurements are accurate to about 1 nT. The calibration uncertainty in the Iridium measurements is identified as a major error source, and a method is developed to calibrate the spacecraft measurements using data from a subset of the INTERMAGNET observatory network producing quasi-definitive data on a regular basis. After calibration, the Iridium data produced main field models with approximately 20 nT average error and 40 nT maximum error as compared to the CHAOS-7.2 model. For many scientific and precision navigation applications, highly accurate Swarm-like measurements are still necessary, however, the Iridium-based models were shown to meet the WMM error tolerances, indicating that Iridium is a viable data source for future WMMs. Graphical Abstract

Ajeet K. Maurya, Navin Parihar, Adarsh Dube et al.

Abstract We report rare simultaneous observations of columniform sprites and associated gravity waves (GWs) using the Transient Luminous Events (TLEs) camera and All-sky imager at Prayagraj (25.5° N, 81.9° E, geomag. lat. ~ 16.5° N), India. On 30 May 2014, a Mesoscale Convective System generated a group of sprites over the north horizon that reached the upper mesosphere. Just before this event, GWs (period ~ 14 min) were seen in OH broadband airglow (emission peak ~ 87 km) imaging that propagated in the direction of the sprite occurrence and dissipated in the background atmosphere thereby generating turbulence. About 9–14 min after the sprite event, another set of GWs (period ~ 11 min) was observed in OH imaging that arrived from the direction of the TLEs. At this site, we also record Very Low Frequency navigational transmitter signal JJI (22.2 kHz) from Japan. The amplitude of the JJI signal showed the presence of GWs with ~ 12.2 min periodicities and ~ 18 min period. The GWs of similar features were observed in the ionospheric Total Electron Content variations recorded at a nearby GPS site. The results presented here are important to understand the physical coupling of the troposphere with the lower and upper ionosphere through GWs.

Anna Morozova, Rania Rebbah

Here we present the results of the comparative analysis of the regular daily variations of the geomagnetic field, Sq and SD, obtained from the observations with two methods: (1) using the so-called geomagnetically quiet day (QD) to calculate mean daily variations and (2) using the principal component analysis (PCA) to decompose original series into main variability modes. The original geomagnetic field series were obtained at the Coimbra Magnetic Observatory (COI, Portugal) in 01.01.2007-31.12.2017. The data were analyzed separately for each of 12 months. The geomagnetic field components X, Y and Z were analyzed independently. The Sq and SD variations obtained with QD were compared with the principal components from PCA (PCs, daily variation of the geomagnetic field of different types) using the correlation analysis. In this study only the PCA ability to extract daily variations similar to ones acquired using the standard approach with QD was analyzed. The results for X, and Y and Z are essentially different. The Sq variation is always filtered to the 1st PCA mode for Y and Z, whereas the SD variation is filtered either to the 2nd or 3rd mode. For X the Sq variation tends to be filtered to the 2nd mode, while the SD variation is more often filtered to the 1st mode. The number of the PCs classified either as Sq or SD follows seasonal and decadal variations of the geomagnetic activity. The analysis showed that PCA can automatically extract the Sq variation from the observations of Y and Z; however complementary analysis (for example, a comparison to a reference curve) is needed to identify a PC corresponding to the SD variation. For X component, the automatic extraction of the Sq or SD variations is not possible, and the complementary analysis is always needed. The dataset used in this paper is described in detail in a companion paper by Morozova et al. (2021a).

A. Anduaga, A. Anduaga

<p>This paper examines how ionospheric physics emerged as a research speciality in Britain, Germany, and the United States in the first four decades of the 20th century. It argues that the formation of this discipline can be viewed as the confluence of four deep-rooted traditions in which scientists and engineers transformed, from within, research areas connected to radio wave propagation and geomagnetism. These traditions include Cambridge school's mathematical physics, Göttingen's mathematical physics, laboratory-based experimental physics, and Humboldtian-style terrestrial physics. Although focused on ionospheric physics, the paper pursues the idea that a dynamic conception of scientific tradition will provide a new perspective for the study of geosciences history.</p>

K. Kuzanyan, N. Kleeorin, I. Rogachevskii et al.

The tilt angle, current helicity and twist of solar magnetic fields can be observed in solar active regions. We carried out estimates of these parameters by two ways. Firstly, we consider the model of turbulent convective cells (super-granules) which have a loop floating structure towards the surface of the Sun. Their helical properties are attained during the rising process in the rotating stratified convective zone. The other estimate is obtained from a simple mean-field dynamo model that accounts magnetic helicity conservation. The both values are shown to be capable to give important contributions to the observable tilt, helicity and twist.

D. Nurgaliev, V. Shcherbakov, A. Kosterov et al.

Liangliang Lou, Qiang Li, Zengchao Zhang et al.

With the increasing number of private vehicles, intelligent parking space management systems (IPSMS) are widely used to analyze the parking spaces status information and to improve parking efficiency. The wireless vehicle detectors (WVD) based on the magnetic sensor have been widely used in IPSMS to collect the information of parking spaces. However, due to the existence of magnetic signal blind zone between the front and rear wheels of high-chassis vehicles, the accuracy of the single magnetic sensor based detector decreases markedly in detecting high-chassis vehicles such as SUVs, MPVs, Pickups, etc. In order to improve the performance of WVDs, this paper proposes a vehicle detection method based on the fusion of the Ultra- Wideband (UWB) ranging measurements and magnetic signals to improve the vehicle detection accuracy. We have designed several WVD prototypes based on our method and deployed them in the actual parking spaces to verify and evaluate the performance of our proposed algorithm. The experimental results show that the vehicle detection accuracy of our proposed method is about 8.4% higher than that of the conventional single magnetic sensor based method.

Yilan Xing, Jian-yi Li, Xing-hui Wang

In view of the difficulty of parking, it is urgent to build an intelligent parking system. In this paper, a wireless parking detector based on geomagnetic detection and NB-IoT technology is proposed. The parking detector consists of three parts: the STM32 microcontroller, the geomagnetic sensor and the NB wireless module. Geomagnetic sensor collects the intensity of the magnetic field around, and then the magnetic field intensity is sent to the microcontroller. The microcontroller determines whether the parking space is occupied by the algorithm, and then transfers the occupancy of the parking space to the background management system in real time through NB.