Earth's Magnetic Field Research Articles

Improving the performance of the GPS/INS integrated navigation system by using the real-time kinematic method

Introduction: This paper presents a method for improving the accuracy of a GPS/INS integrated navigation system. Estimating the yaw angle, which is the degree of deviation from the north, is a crucial aspect in the navigation and control of autonomous robots. Methods: We can use an inertial measurement unit (IMU) to calculate the yaw angle, but the accuracy is heavily reliant on the Earth's magnetic field. This field can vary in value as the vehicle moves and is easily disturbed by external sources such as electrical devices and motors. To circumvent these limitations, a dual-antenna GPS with the real-time kinematic (RTK) method is utilized to improve the quality of the yaw angle estimation. Results: This approach eliminates the use of magnetometers, and the experimental results show that the error can be significantly reduced to 0.16 degrees with a baseline of 1 meter. Conclusion: When compared to the standard GPS/INS system, the proposed method using GPS-RTK provides better accuracy, even when the GPS signal is lost.

Napredniji teorijski model EM polja sfere Zemlje u stranom homogenom EM polju

Introduction/purpose: The paper describes a more advanced theoretical model of the Earth's EM field based on two-component hypotheses. A defined mathematical model that shows the rotation of the magnetically conducting sphere of Tthe magnetization M in a foreign magnetic field and the components of the magnetic field that may arise due to the rotation of the Earth around its axis. According to the established model, in relation to the reference values of the planet Earth, the values of the components of the other planets in the solar system were calculated and the results were tabulated. Methods: The solution to the problem highlighted in the title of the paper was determined using the combined, for that purpose, formalized methods of physics and mathematical analysis, in order to develop a new, more advanced mathematical model. For this purpose, the method of analogy was used, related to the application of similar structural forms and systems for researching electromagnetic processes and planetary rotation. The method of analogy was applied for two interrelated reasons. The first one is that all values that characterize the function of any natural system are subject to change, and the second one is that the applied solutions do not determine the conditions of the structure's function in each specific case. Results: The solutions in the form of original analytical formulas and numerical values arranged in Table 2, referring to the influence of the rotation of the planets and especially the Earth, will be applied to research the effects of the EM field emitted by the Sun towards the planets, especially the role that the process plays in protecting the planet Earth. The results given in Table 2 are particularly important. Conclusion: The paper discusses the appearance and effect of the Earth's EM field in a way that is understandable at the current level of scientific development. Scientific findings in science and measurements in geoand astrophysics indicate the Sun as a possible source of the EM field that extends through interplanetary space and the component of the Earth's magnetic field is only a response to the influence of that source. Natural phenomena and processes on the Earth can be defined in system theory by a model that contains changes in the parameters of the state of the planet.

Design and analysis of the Macau Science Satellite-1’s laser retro-reflector array

The origin and spatial−temporal variation of the Earth’s magnetic field (EMF) is one of the important scientific problems that has long been unsolved. The Macau Science Satellite-1 (MSS-1) under construction is China’s first high-precision EMF measurement satellite. To satisfy the highly precise requirements of the MSS-1 orbit measurement, a light, high-precision, four-prism laser retro-reflector array was designed. It weighs approximately 285 g, its effective reflection area is greater than 1.77 cm², and its size is 100 × 100 × 41 mm. The laser retro-reflector array has excellent performance, and it can achieve a ranging precision at the subcentimeter level for satellite laser ranging. It will be developed and installed on the MSS-1 as a power-free load for high-precision orbit measurement and accurate orbit calibration. The MSS-1 is planned to be brought into the International Laser Ranging Service observations. More than 31 satellite laser ranging stations in the International Laser Ranging Service around the world will be able to measure the MSS-1 with long arcs, which will support the scientific mission of high-precision EMF exploration.

Earth's field NMR relaxation of pre-polarised water protons for real-time detection of free-radical formation.

Real-time imaging of free-radical formation is important in physical chemistry, biochemistry, and radiobiology, especially for the study of radiation dose-rate effects. Herein, we show for the first time that the formation of free radicals during the time course of a chemical reaction can be imaged through NMR relaxation measurements of water protons in the Earth's magnetic field, in an open-coil spectrometer. The relaxation rate constants of water magnetisation are enhanced as reactions leading to the formation of hydroxyl radicals and oxygen proceed on the timescale of tens of minutes. The reaction rate of iodide-catalysed H2O2 decay was followed by Earth-field 1H NMR relaxation in real time. The relaxivities of the reaction product and several other paramagnetic compounds were determined. Spin-trap molecules were then used to capture ˙OH radical species, thus altering the reaction rate in proportion to the formation of new paramagnetic compounds. Thereby, a new experimental method for magnetic resonance imaging of the formation of intermediate and stable radical species in water is proposed.

UFKW Propagation in the Dissipative Thermosphere

Abstract“Ultra‐fast” Kelvin waves (UFKWs) serve as a mechanism for coupling the tropical troposphere with the mesosphere, thermosphere and ionosphere. Herein, solutions to the linearized wave equations in a dissipative thermosphere in the form of “Hough Mode Extensions (HMEs)” are employed to better understand the vertical propagation of the subset of these waves that most effectively penetrate into the thermosphere above about 100 km altitude; namely, UFKWs with periods ≲4 days, vertical wavelengths (λz) ≳30 km, and zonal wavenumber s = −1. Molecular dissipation is found to broaden latitude structures of UFKWs with increasing height while their vertical wavelengths (λz) increase with latitude. Collisions with ions fixed to Earth's magnetic field (“ion drag”) are found to dampen UFKW amplitudes, increasingly so as the densities of those ions increase with increased solar flux. The direct effect of ion drag is to decelerate the zonal wind. This leads to suppression of vertical velocity and the velocity divergence, and related terms in the continuity and thermal energy equations, respectively, that lead to diminished perturbation temperature and density responses. Access is provided to the UFKW HMEs analyzed here in tabular and graphical form, and potential uses for future scientific studies are noted.

Estimation of the Magnetic Signature of Ferromagnetic Nanoparticles by Earth’s Magnetic Field

Envisioning the next generation electrified chemical reactors heated by induction that will be able to provide feedback on the material properties online, allowing early diagnosis of potential problems, authors in this paper study the magnetic behavior of supported cobalt (catalytic) nanoparticles, with both face-centered cubic (fcc) and hexagonal close pack (hcp) crystal structure, when the Earth magnetic field is applied. The investigation and corresponding simulations have been performed with finite element analysis. The magpar software has been used, allowing simulation of the hysteresis loop for each ferromagnetic sample. The influence of the next neighbor distance and the impact of the number of the particles on the hysteresis loop are studied. The magnetizations of each cobalt-based sample, along with the hysteresis loop have been calculated by simulations and validated by experiments with satisfactory agreement.. Simulations indicate that the number of the particles (different size, under the same total mass) does not affect the hysteresis loop of the material, while the next neighbor distance, has a significant influence. The objective of the present research paper is to develop a novel, versatile, low cost, in situ method for simulating and evaluating magnetic fields generated from heterogeneous catalysts targeting to real-time remote monitoring diagnostics of the catalytic process.

Simulation of Chorus Wave Excitation in the Compressed/Stretched Dipole Magnetic Field

AbstractThe properties of chorus waves have been extensively studied, which are important to understand chorus generation and wave‐particle interactions between chorus and energetic electrons. Observations reveal that there exists a distinct day‐night asymmetry for the properties of chorus waves, such as the sweep rate and duration, which is predicted to be relevant to the asymmetric configuration of Earth's background magnetic field. In this paper, using the one‐dimensional (1‐D) particle‐in‐cell (PIC) simulation model with a compressed/stretched dipole magnetic field, we study the dependences of the properties of rising‐tone chorus waves on the background magnetic field. It is demonstrated that the saturated amplitude and the chorus sweep rate increase while the chorus duration decreases with an increase of the compression factor ξ, which represents the compression/stretch degree of the field line. Moreover, the threshold of exciting chorus waves in the compressed dipole field is generally lower than that in the stretched dipole field. These results are useful to understand the chorus excitation and the day‐night asymmetry of chorus properties.

About the Propagation of RSDN‐20 “Alpha” Signals in the Earth‐Ionosphere Waveguide During Geomagnetic Disturbances

AbstractThe paper presents the results of the modeling of VLF radio waves propagation in horizontally inhomogeneous region of the high‐latitude Earth‐ionosphere waveguide during different types of the geomagnetic disturbances. The frequencies of the model source of signal correspond to the frequencies of the long‐distance navigation radio system RSDN‐20 “Alpha” constantly broadcasting in the VLF range in the Russian Federation. It is considered the geomagnetic storm on 24 January 2012 and geomagnetic substorm on 11 December 2015. Electron density profiles and collision rates of electrons with neutrals are taken from the measurements of EISCAT radar in Tromso and EISCAT 42m radar on Svalbard. The numerical experiments were conducted with a highly horizontally inhomogeneous electron density in the ionosphere. It is shown that the amplitudes and phases of the VLF signals at these frequencies show a noticeable reaction to changes in the ionospheric parameters during the considered geomagnetic disturbances. Calculations show that changes in amplitude of RSDN‐20 “Alpha” signals caused by the action of the Earth's magnetic field and horizontal inhomogeneities depend on the direction of signal propagation relative to the Earth's magnetic field vector and cannot be reversed if the direction of propagation changes to the opposite. The results of the numerical experiment were compared with the corresponding characteristics of the RSDN‐20 signals calculated from the observations of electromagnetic signals at the Lovozero observatory for the case on 11 December 2015.

Статистические свойства магнитного поля земли перед землетрясением, сопровождаемым цунами

A method for predicting earthquakes accompanied by tsunamis based on changes in the statistical properties of the Earth's magnetic field is proposed. Geomagnetic field is analyzed using the measurements taken a few days before the earthquake in the Pacific Ocean. With the help of a statistical functional, which allows one to study the variations in the level of chaos in the random process, the arising a set of structures with a high degree of determinism is revealed. The properties of these structuews can be interpreted as precursors of an earthquake accompanied by a tsunami.

Accuracy estimation of the calculating algorithm the satellite’s orbit of earth remote sensing

Transformations of the coordinate systems in which the reference vectors of the initial navigation information - the flow of sunlight and the Earth's magnetic field are set - into the coordinate system of the sun-synchronous orbit of the Earth's remote sensing satellite by matrix and analytical methods are considered. The influence of the accuracy of calculating the direction cosines of the satellite orientation matrices on the accuracy of determining its orientation angles and the scanning accuracy is estimated. The estimation of the influence on the accuracy of determining the satellite orientation of the sensor errors of the primary navigation information and the features of the matrix orientation algorithm is carried out. Analytical dependencies are obtained that allow one to evaluate the influence of the noted factors depending on the position of the satellite in its orbit and the motion of the Earth along the ecliptic.

Orbitally and galactic cosmic forced abrupt climate events during the last glacial period

Various abrupt climate events have been reported during the last glacial period, but their regional expressions and causes remain complex and not fully understood largely due to lack of high-resolution paleoclimate records. In this study, a high-resolution loess sequence is presented from North China which is significantly influenced by the East Asian Summer Monsoon, and its multiple proxies reveal two strong, abrupt cooling-drying events occurring at 48 ka and ∼42 ka. The 48 ka event corresponds to the fifth Heinrich (H5) event that was characterized by catastrophic iceberg discharges into the subpolar North Atlantic Ocean. Our loess and model results suggest that the 48 ka event could result from the unique and extreme orbital configuration at 48 ka, characterized by the smallest latitudinal summer insolation gradient over the last glacial period. This orbital configuration led to a cooling-drying in the low and mid-latitudes but a warming in high latitudes. The ∼42 ka event corresponds to a catastrophic environmental crisis discovered on the Eurasian and Australian continents. It also corresponds to a major reversal of the Earth's magnetic poles, i.e., the Laschamps Excursion. The cosmic ray increase due to this Excursion could affect the pedogenesis and dust deposition of the loess sequence via cloud increase, regional cooling, aerosol increase and local wind strengthening. This study is a clear demonstration that both extreme orbital conditions and the change of the Earth's magnetic field could cause abrupt climate and environmental changes.

The Earth's Magnetic Field Enhances Solar Energy Deposition in the Upper Atmosphere

AbstractThe presence of a large‐scale planetary magnetic field is thought to be a protective factor for atmospheres, preventing them from being blown off by the solar wind. We focus on one key aspect of atmospheric escape: how does a planetary magnetic fields affect the energy transfer from the Sun to the atmosphere? We estimate the solar wind energy currently dissipated in the Earth's atmosphere using empirical formulas derived from observations. We show that it is significantly higher than the energy dissipated in the atmosphere of a hypothetical unmagnetized Earth. Consequently, we conclude that the Earth's magnetic field enhances the solar energy dissipation in the Earth's atmosphere and that, contrary to the old paradigm, an intrinsic magnetic field does not necessarily reduces atmospheric loss.

Online Monitoring of Magnetometer Signals for Estimating Induced Electric Fields in Power Systems

Powerful solar storms emit plasma that may travel towards the earth. Interactions between the plasma and the earth magnetic field cause geomagnetic disturbances (GMDs), which in turn induce quasi-dc voltage along long conductors in power systems. The induced electric field can be calculated by magnetic field data measured by magnetometers at several stations. In this paper, a set of online processing methods are proposed to improve signal to noise ratio (SNR) of the calculated electric field signals. In the first step, magnetic field signals are denoised inside a sliding window by a wavelet transform. The sliding window width is optimized and the introduced transients are compensated. Time derivative of magnetic field signals are estimated by a continuous wavelet transform in the next step, and the size of the sliding window is minimized for optimal computational speed. Ultimately, a method is proposed to further enhance the SNR by updating the previously processed data points. The magnetic and electric field signals obtained by the online and offline processing methods are compared with each other. It is demonstrated that the online processing methods can decrease the noises to a level comparable to that obtained by the offline methods. The results of this study can be implemented to protect key elements of power systems against severe solar storms.

Validation and optimization of the GSAMQ analytical propagator for spin-stabilized satellite

The aim of this paper is to validate the analytical propagator through simulations comparing the results with the real data and to optimize the work's source code so that it is processed faster. This work analyzes the use of the quadrupole model in the Earth's magnetic field when an analytical propagator calculates eddy current and residual magnetic torques in spin-stabilized satellites. For that, the components of the gravity gradient torque, the solar radiation torque and aerodynamics torque are also included. The simulations are carried out for a predetermined period and use data from the SCD1 Brazilian satellite, provided by the National Institute for Space Research (INPE). The results are then compared with the real data to validate the propagator. The propagator with the quadrupole model is called GSAMQ and uses the mean deviations of the magnitude of the spin velocity, and the angles of right ascension and declination of the spin axis as evaluation parameters. A statistical approach is included in this analysis and shows the model's accuracy.

A Robust Tracking Method for Multiple Moving Targets Based on Equivalent Magnetic Force.

A ferromagnetic vehicle, such as a submarine, magnetized by the Earth's magnetic field produces a magnetic anomaly field, and the tracking of moving targets can be realized through real-time analysis of magnetic data. At present, there are few tracking methods based on magnetic field vectors and their gradient tensor. In this paper, the magnetic field vector and its gradient tensor are used to calculate equivalent magnetic force. It shows the direction of the vector between the detector and the tracking targets for controlling the direction of motion of the detector and achieving the purpose of tracking. Compared with existing positioning methods, the proposed method is relatively less affected by instrument resolution and noise and maintains robustness when the velocity vectors of multiple magnetic targets change randomly.

MCADAM: A Continuous Paleomagnetic Dipole Moment Model for at Least 3.7 Billion Years

AbstractUnderstanding the evolution of Earth's magnetic field can provide insights into core processes and can constrain plate tectonics and atmospheric shielding. The absolute paleointensity database PINT provides a curated repository of site mean (i.e., cooling unit), estimates of the strength of the magnetic field. We present a minor update to the PINT database to version 8.1.1 by adding 295 records from 34 studies. The PINT database is used to define a continuous model of the dipole field, using an approach combining non‐parametric and Monte Carlo (MC) resampling termed Monte Carlo Axial Dipole Average Model (MCADAM). Three dipole field strength models spanning 50 ka to 3.7–4.2 Ga (MCADAM.1a‐c) are presented, reflecting three tiers of increasingly more stringent data selection. The MCADAM models allow for the estimation of the magnetic standoff distance, constraining the shielding of Earth's atmosphere against solar wind erosion provided by the geodynamo.

The inherent instability of axisymmetric magnetostrophic dynamo models

Recent studies have demonstrated the possibility of constructing magnetostrophic dynamo models, which describe the slowly evolving background state of Earth's magnetic field when inertia and viscosity are negligible. Here we explore the properties of steady, stable magnetostrophic states as a leading order approximation to the slow dynamics within Earth's core. For the case of an axisymmetric magnetostrophic system driven by a prescribed α-effect, we confirmed the existence of four known steady states: , , where is purely dipolar and is purely quadrupolar. Importantly, here we show that in all but the most weakly driven cases, an initial magnetic field that is not purely dipolar or quadrapolar never converges to these states. Despite this instability, we also show that there are a plethora of instantaneous solutions that are quasi-steady, but nevertheless unstable. If the dynamics in Earth's core are reasonably modelled by a strongly driven α-effect, this work suggests that the background state can never be steady. We discuss the difficulties in comparing our magnetostrophic models with geomagnetic timeseries.

Seismic Induced Ground Deformation and Ionospheric Perturbations of the 29 July 2021, Mw 8.2 Chignik Earthquake, Alaska

AbstractThe subsurface, surface, and ionospheric characteristics associated with the 29 July 2021 Mw 8.2 Chignik Earthquake are studied in detail using continuous Global Positioning System (cGPS) data over Alaska. The cGPS‐inverted coseismic displacements demonstrate that the slip is distributed along the rupture area northeast of the epicenter with a maximum coseismic slip of ∼3.85 m occurring at a depth of ∼24.25 km. The vertical surface displacement estimated from the coseismic slip exhibits a similar deformation pattern with a maximum uplift of ∼1.0 m over the highly slip area. The ionospheric electron density perturbations associated with the Chignik earthquake were investigated using cGPS‐derived Total Electron Content (TEC) data. Unlike the northeast‐directed coseismic rupture and surface uplift, the ionospheric imprints of this event are more dominant southwest of the epicenter. This study reveals that the Earth's magnetic field and the ionospheric background electron density significantly controlled the TEC perturbation orientation and amplitudes rather than the rupture propagation and coseismic uplift pattern.

Lack of evidence for a fine-scale magnetic map sense for fall migratory Eastern North American monarch butterflies (Danaus plexippus).

How first-time animal migrants find specific destinations remains an intriguing ecological question. Migratory marine species use geomagnetic map cues acquired as juveniles to aide long-distance migration, but less is known for long-distance migrants in other taxa. We test the hypothesis that naïve Eastern North American fall migratory monarch butterflies (Danaus plexippus), a species that possesses a magnetic sense, locate their overwintering sites in Central Mexico using inherited geomagnetic map cues. We examined whether overwintering locations and the abundance of monarchs changed with the natural shift of Earth's magnetic field from 2004 to 2018. We found that migratory monarchs continued to overwinter at established sites in similar abundance despite significant shifts in the geomagnetic field, which is inconsistent with monarchs using fine-scale geomagnetic map cues to find overwintering sites. It is more likely that monarchs use geomagnetic cues to assess migratory direction rather than location and use other cues to locate overwintering sites.

Links between geomagnetic activity and atmospheric cold fronts passage over the Belgrade region, Serbia

AbstractThe suggestion that variations in solar irradiance affect Earth's weather and climate is based on correlations between solar and meteorological parameters. Solar activity influences the Earth's magnetic field. The geomagnetic activity index (GAI) is one of the indexes that measure this influence. In this paper, we researched the link between GAI and the passage of atmospheric cold fronts (CFs) over the Belgrade region, Serbia. Three years of daily data for solar (coronal holes, protons velocity and density), geomagnetic (GAI, electrical potential of Earth's atmosphere) and meteorological (air temperature, wind and precipitation) parameters were analysed. We developed a methodology that established pairs of GAI peaks and CFs and found the time interval (TI) between them. In 88.5% of cases, we were able to pair a GAI and a CF, while in 11.44% pairing could not be established. The number of GAI peaks without assigned CFs increased as mean values of GAI decreased. Most frequently, following an increase in the GAI, a CF passed after 7 days (relative frequency 22.8%), followed by 6 days (19.9%) and 8 days (18.5%). These three TIs covered, in sum, 61.3% of cases. Mean TI value was 6.82 days. The warm part of the year had the same TI distribution but the cold part of the year produced a bimodal frequency, with a maximum of 8 days (21.6%), followed by 5 (18.3%) and 6 days (17.6%). The most frequent CFs passing over Belgrade are from WNW‐N (67.1%) and SSW‐W (27.6%) quadrants.