Terrestrial Magnetic Field Research Articles

Spontaneous generation and reversal of helicity in anisotropic turbulence.

Helicity plays an important role in spectacular geophysical phenomena such as hurricanes or the generation of the terrestrial magnetic field. The present investigation shows how helicity can be created in a statistically homogeneous but anisotropic flow, driven by buoyancy. If the flow is close enough to a two-dimensional limit, spontaneous symmetry breaking leads to the generation of mean helicity. In particular, we explain these observations by identifying a simple linear mechanism, the relevance of which is illustrated by simulations of unstably stratified turbulence in a conducting fluid on which a magnetic field is imposed. Finally it is shown that the self-organized state displays dynamical reversals of the sign of the mean helicity.

Observations and Simulations of Dropout Events and Flux Decays in October 2013: Comparing MEO Equatorial With LEO Polar Orbit

AbstractWe compare ESA PROBA‐V observations of electron flux at LEO with those from the NASA Van Allen Probes mostly at MEO for October 2013. Dropouts are visible at all energy during four storms from both satellites. Equatorially trapped electron fluxes are higher than at LEO by 102 (<1 MeV) to 105 (>2.5 MeV). We observe a quite isotropic structure of the outer belt during quiet times, contrary to the inner belt, and pitch angle dependence of high energy injection. We find a very good overlap of the outer belt at MEO and LEO at ∼0.5 MeV. We use test‐particle simulations of the energetic electrons trapped in the terrestrial magnetic field to study the outer radiation belt electron flux changes during geomagnetic storms. We show that the Dst (Disturbance storm time) effect during the main phase of a geomagnetic storm results in a betatron mechanism causing outward radial drift and a deceleration of the electrons. This outward drift motion is energy independent, pitch angle‐dependent, and represents a significant distance (∼1 L‐shell at L = 5 for moderate storms). At fixed L‐shell, this causes a decay of the LEO precipitating flux (adiabatic outward motion), followed by a return to the normal state (adiabatic inward motion) during main and recovery phases. Dst effect, associated with magnetopause shadowing and radial diffusion can explain the main characteristics of outer radiation belt electron dropouts in October 2013. We also use Fokker‐Planck simulations with event‐driven diffusion coefficients at high temporal resolution, to distinguish instantaneous loss from the gradual scattering that depopulates the slot region and the outer belt after storms. Simulations reproduce the slot formation and the gradual loss in the outer belt. The typical energy dependence of these losses leads to the absence of scattering for relativistic and ultra‐relativistic electrons in the outer belt, oppositely to dropouts.

Possible risk resulting from the recent decay of the dipolar component of the terrestrial magnetic field

In this study, we investigated the geomagnetic ground observatory data from 1980 to 2011 collected from World Data Center from 134 stations. To analyze the data we have applied spherical harmonic decomposition to obtain components associated with the Earth’s main magnetic field and to calculate how the Earth’s dipole was varying in the aforementioned recent 31-year period. There is a visible ~ 2.3% decay of the dipole magnetic field of the Earth. We note that the present-day value of the magnetic dipole intensity is the lowest one in the history of modern civilization and that further drop of this value may pose a risk for different domains of our life.

Indoor Positioning via Artificial Magnetic Fields

Indoor positioning approaches are often based on electromagnetic wave signals with high frequency. However, signal reflections and the corresponding signal superpositions are challenging. As a result, there is still no indoor positioning technology established in commercial products, such as smartphones or smartwatches. Recent publications have shown that this indoor positioning problem can be addressed by using artificial magnetic fields. However, the cubic attenuation of the magnetic field challenges technical implementations and limits the ranges. In this work, we propose an approach striving to address these issues of magnetic indoor positioning via a simple electromechanical single-anchor concept in combination with a small wearable sensor circuitry. The terrestrial magnetic field together with amplitude and phase measurements resolves the position and the orientation of the tag. The proposed indoor positioning approach via artificial magnetic fields is tested in a corridor for a spatial region of approximately 100 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The mean positioning error in this experiment was calculated to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu =1.0\pm 0.81\,\,\mathrm {m}$ </tex-math></inline-formula> . The proposed indoor positioning approach via artificial magnetic fields and the corresponding measurement system can, therefore, be useful alternatives when considering applications in which simple implementation is more important than positioning precision.

Magnetotelluric transect across the São Luís cratonic fragment, the Gurupi belt and the Parnaíba basin, N-NE Brazil

The study area is located in the N-NE region of Brazil where Precambrian rocks of the São Luís Cratonic Fragment and the Gurupi belt are overlain by Phanerozoic sediments of the Parnaíba and São Luís basins, making the assessment of the extents of these geotectonic domains difficult. One of the main objectives of the present study was to elaborate a NNW-SSE-trending, 180-km long magnetotelluric transect, aiming to identify the geotectonic domains of the study area by means of their geoelectric characteristics. The magnetotelluric (MT) technique is a geophysical method that detects the natural variations of the terrestrial electric and magnetic fields so as to investigate the geoelectric characteristics of the subsurface. By means of a MT survey for field data acquisition, calculation of impedance tensors and 2D inversion modeling, the geophysical transect and additionally an interpretive geological model were elaborated for the study area. The combined transverse electric (TE) and transverse magnetic (TM) geophysical model revealed superficial conductive (Parnaíba and São Luís basins and sedimentary coverings), resistive (São Luís Cratonic Fragment) and very resistive (Gurupi mobile belt) portions up to depths of the order of 15 km. These results attested for correlations between the São Luís Craton (South American Plate) and the West African Craton (African Plate), especially regarding the Gurupi Belt (in Brazil) and the Rokelide Belt (in Liberia), which are considered to be the boundaries of a triple junction related to the supercontinent Rodinia taphrogenesis. Besides presenting an unprecedented geophysical investigation along the São Luís Cratonic Fragment and the Gurupi Belt, this study promotes the discussion on the correlations between the Brazilian Gurupi and the African Rokelide belts for metallogenetic purposes.

Archaeological Investigation at the Urartian Sites of Bastam Castle Using Magnetics Method

Archaeological Investigation at the Urartian Sites of Bastam Castle Using Magnetics Method

Magnetic circular dichroism in Archean atmosphere and asymmetric photolysis of biomolecules: enantiomeric excess of prebiotic sugar.

In the terrestrial dipolar magnetic field, magnetic circular dichroism (MCD) of UV sunlight by paramagnetic O2 in an Archean atmosphere (mostly CO2 and N2) results in circular polarization anisotropy (~ 10-10). This is used to calculate enantiomeric excess (EE~10-13) of glyceraldehyde (3-carbon sugar) with a model that includes racemic production and asymmetric photolysis of its enantiomers. The sign and magnitude of enantiomeric excess (EE) vary with the Earth's latitude. Unlike random noise fluctuation in spontaneous mirror symmetry breaking (SMSB) models, the sign of EE is deterministic and constant over large areas of prebiotic Earth. The magnitude is several orders greater than the mean amplitude of stochastically fluctuating EE. MCD could provide the initial EE for growth of homochirality by asymmetric autocatalysis.

Study of the Influence of the Solar Wind Energy on the Geomagnetic Activity for Space Weather Science

Abstract This paper addresses the investigation of the interaction of the solar wind energy with the Earth’s magnetosphere, by studying its correlation with the disturbance storm time (Dst) index, a proxy of the geomagnetic activity. Some relevant parameters of the solar wind (the bulk speed and the z-component of the interplanetary magnetic field) are explored in the energy−Dst space. It results that (i) the solar wind energy and the geomagnetic activity are strictly related, with the coronal mass ejections representing the most energetic and geoeffective driver; (ii) the slow solar wind has negligible effects on Earth regardless of its energy content, whereas high-speed streams may induce severe geomagnetic storming depending on the advected energy; and (iii) while at low and mid energies, geomagnetic disturbances are induced provided the magnetic reconnection between the interplanetary and terrestrial magnetic fields occurs, high-energy solar wind plasma can impact Earth even without reconnecting with the geomagnetic field at the dayside magnetopause. The most significant result in the framework of space weather science resides in the observational evidence that the Earth’s magnetosphere has a maximum response to the energetic content of the solar wind, which leads to the derivation of an empirical law allowing the proper forecast of the upper limit of the intensity of any geomagnetic disturbance on the basis of the solar wind energy derived in situ at the Lagrangian point L1.

Concurrent Observations Of Magnetic Reconnection From Cluster, IMAGE and SuperDARN: A Comparison Of Reconnection Rates And Energy Conversion

AbstractAuroral emissions reflect energy dissipation in the atmosphere, while the energy mostly originates from the magnetospheric dynamics of the planet. In the Earth's magnetosphere, the interaction between the solar wind and the terrestrial magnetic field produces magnetic reconnection ultimately causing the appearance of auroras in the polar regions. In this study, we revisit two reconnection events previously identified using ESA Cluster observations during conditions of moderate geomagnetic activity, in the magnetotail. We compare these in situ detections with simultaneous global auroral images from the NASA‐IMAGE satellite and ionospheric convection measurements from SuperDARN. We show for the first time a direct correspondence between the electric voltage estimated at ionospheric altitude and the reconnection rate at the reconnection site. We compute the total auroral precipitation power and compare it to the energy released from the reconnection site. We deduce that the precipitated electron power of the aurora and the electron energy deposition rate from the reconnection site are of the same order of magnitude, which means that the thermal energy released by reconnection is primarily transferred to the ionosphere and contributes to the auroral activity.

Chemo‐ and Magnetotaxis of Self‐Propelled Light‐Emitting Chemo‐electronic Swimmers

AbstractMiniaturized autonomous chemo‐electronic swimmers, based on the coupling of spontaneous oxidation and reduction reactions at the two poles of light‐emitting diodes (LEDs), are presented as chemotactic and magnetotactic devices. In homogeneous aqueous media, random motion caused by a bubble‐induced propulsion mechanism is observed. However, in an inhomogeneous environment, the self‐propelled devices exhibit positive chemotactic behavior, propelling themselves along a pH or ionic strength gradient (∇pH and ∇I, respectively) in order to reach a thermodynamically higher active state. In addition, the intrinsic permanent magnetic moment of the LED allows self‐orientation in the terrestrial magnetic field or following other external magnetic perturbations, which enables a directional motion control coupled with light emission. The interplay between chemotaxis and magnetotaxis allows fine‐tuning of the dynamic behavior of these swimmers.

Chemo- and Magnetotaxis of Self-Propelled Light-Emitting Chemo-electronic Swimmers.

Miniaturized autonomous chemo-electronic swimmers, based on the coupling of spontaneous oxidation and reduction reactions at the two poles of light-emitting diodes (LEDs), are presented as chemotactic and magnetotactic devices. In homogeneous aqueous media, random motion caused by a bubble-induced propulsion mechanism is observed. However, in an inhomogeneous environment, the self-propelled devices exhibit positive chemotactic behavior, propelling themselves along a pH or ionic strength gradient (∇pH and ∇I, respectively) in order to reach a thermodynamically higher active state. In addition, the intrinsic permanent magnetic moment of the LED allows self-orientation in the terrestrial magnetic field or following other external magnetic perturbations, which enables a directional motion control coupled with light emission. The interplay between chemotaxis and magnetotaxis allows fine-tuning of the dynamic behavior of these swimmers.

Magnetic Simulator Testbed for APSCO Student Small Satellite Project

The Student Small Satellite (SSS) is a university project of Asia-Pacific Space Cooperation Organization (APSCO), composed by one microsatellite (SSS-1) and two 3U CubeSats (SSS-2A and SSS-2B). Regarding SSS-1 and SSS-2A satellites, the active 3-axis magnetic control strategy has been applied in the Attitude Determination and Control System (ADCS). In this paper, the necessary study for the development of a Magnetic Simulator Testbed for the SSS-1 and SSS-2A satellites was performed using one pairs of Helmholtz coils for each axis of rotation (X, Y, Z). Each pair of coil can generate a sufficiently large and stable magnetic field that simulate the Earth’s magnetic field but with a reliable level of accuracy, to perform the ADCS test on the satellites. Matlab software was used to generate the propagation of the orbit for the satellites, to calculate the Earth’s magnetic field around that orbit and simulate a pair of Helmholtz coil in each axis of rotation to reproduce the Earth’s magnetic field using the Biot-Savart Law. The results obtained for propagation of the orbit, calculation of terrestrial magnetic field and reproduction of the magnetic field through the Magnetic Simulator Testbed, were very close to the results obtained in important researches previously consulted, giving reliability to this research and allowing an analysis to determine the real physical size that Magnetic Testbed should have. The size determined, is very close to what was expected, allowing to conclude the reliability and viability of the development of the Magnetic Testbed for APSCO SSS Project.

An SOC Approach to Study the Solar Wind‐Magnetosphere Energy Coupling

AbstractSolar wind‐magnetosphere interaction and the injection of large quantity of plasma particles into the Earth's magnetosphere are the primary reasons behind geomagnetic storm, auroral effects, and, in general, all the fluctuations observed in the terrestrial magnetic field. In this paper, we analyzed the perturbed magnetosphere as a sandpile‐like cellular automata model based on the concept of self‐organized criticality and many‐body interactive system and proposed a solar wind‐magnetosphere energy coupling function in terms of interplanetary magnetic field BZ, the zth component of interplanetary magnetic field. The function determines the cusp width W depending on the intensity of (−BZ − BTh) where BTh is the threshold value. The model generates two output series, which are the numerical representation of the real‐time Dst index and AE index series, respectively. For our study, the range of years 1997–2007 of the 23rd solar cycle had been considered here. The threshold value BTh plays a significant role in the analysis and exhibits a proportional relationship with the yearly mean total number of sunspots for each year of the range 1997–2007 of the 23rd solar cycle. For each year, the two resultant output time series of the model display high‐correlation coefficients with the real‐time Dst and AE indexes, respectively, which denotes the acceptability of the proposed energy coupling function and its relation with the solar activities.

Variations of geomagnetic cutoff rigidity in the southern hemisphere close to 70°W (South-Atlantic Anomaly and Antarctic zones) in the period 1975–2010

We report the existence of rapid variations in (effective) geomagnetic cutoff rigidity (Rc) between the equatorial and Antarctic zones adjacent to the Andes Mountains, revealed by the variation rate of geomagnetic cutoff rigidity (VRc) in the period 1975–2010. Our analysis is based on empirical records and theoretical models of the variations in cosmic rays and on the structure of geomagnetic fields. These have given us a different view of variations in Rc in time and space along the 70°W meridian, where secular variations in the geomagnetic field are strongly influenced by the proximity of the South Atlantic Magnetic Anomaly (SAMA), one of the most important characteristics of the terrestrial magnetic field that affects our planet, close from the equator to the 50°S parallel and from South America to South Africa. The VRc presents rapid changes in mid-latitudes where SAMA exerts its influence despite the existence of smooth changes in the geomagnetic field. This shows that these changes occur mainly in the spatial configuration, rather than in the temporal evolution of Rc. The analysis was performed using measurements from the Chilean Network of Cosmic Rays and Geomagnetism Observatories, equipped with BF-3 and latest generation He-3 neutron monitors, Fluxgate magnetometers, geomagnetic reference field (IGRF) and Tsyganenko 2001 model (just for completeness).

Performance Investigation of a Silicon Photovoltaic Module under the Influence of a Magnetic Field

Aside from the terrestrial magnetic field that is generated from the earth core, power transmission, and distribution lines, transformers and other equipment do produce a certain amount of magnetic field that could interfere with the performance of photovoltaic modules. This study conducted an experiment and investigated the performance of a silicon photovoltaic module subjected to a magnetic field. The current-voltage and power-voltage characteristics were plotted in the same axis system and allowed us to find, as a function of the magnetic field, the electrical parameters of the photovoltaic module such as maximum electric power, fill factor, conversion efficiency, and charge resistance at the maximum power point. These electrical parameters were then used to calculate the series and shunt resistances of the equivalent circuit of the photovoltaic module. The results have shown that the efficiency of a solar module is affected by the presence of magnetic fields. However, the magnitude of ambient magnetic field generated by power transmissions lines and other equipment is extremely low (in the order of 10−2 mT or less) as compared to the values of the magnetic field used in this study. That made it difficult to conclude as to the impact of such field on solar photovoltaic installations.

Theory of The Three Fields of Space

&#x0D; This article is a logical and rational analysis of the physical phenomena produced by the three fields that are generated in space: gravity field; field of terrestrial nuclear magnetism; and orbital field.&#x0D; Eduardo Guimarães, through the studies of the three nuclear masses of the Sun's nucleus, the three nuclear masses of the moon's nucleus, and the three nuclear masses of the Earth's nucleus.&#x0D; We discover the three spatial fields that are generated in the solar system and in the planets.&#x0D; Then, from the general theory of the three fields of space, we can understand all the mechanics that generate the dynamics and kinematics of celestial bodies.&#x0D; So now we can understand why the smaller celestial bodies orbit the orbital field of the largest celestial bodies.&#x0D; So now we can understand why the planets produce orbits of elliptical motions, around the orbital field of the Sun.&#x0D; Then we understand the orbital mechanics of the little planet Mercury, and its abnormal orbit around the orbiting field of the Sun.&#x0D; Then Mercury has a perihelion precession of 2 degrees per century, due to an approximation of the perihelion of Mercury which is attracted by the micro-gravity of the Sun, generating an orbital deviation of 2 degrees per century.&#x0D; In the future the planet Mercury will lose energy from its nucleus and will not be able to make the orbital curve of the perihelion because it will have been attracted by the gravitational field of the Sun's nucleus.&#x0D; The fall of Mercury on the Sun will generate two thermonuclear explosions of SUPERNOVA.&#x0D; The first thermonuclear explosion of SUPERNOVA will be generated by the thermonuclear collision of the gravity mass attraction of Mercury debris with the Sun's nucleus.&#x0D; The second thermonuclear explosion of SUPERNOVA will be generated by the thermonuclear collision of attraction of the mass of orbital attraction of Mercury debris with the nucleus of the Sun.&#x0D; These two thermonuclear explosions of SUPERNOVA will generate two immense thermonuclear shockwaves that will devastate the entire fragile geo-biome of the solar system.&#x0D; &#x0D;

Influence of the Gravitational Fields of the Moon and the Sun on Long-Period Variations in the Proper Rotation of “Midas” Satellites

We report the results of an analysis of the variation of the proper rotation of several destabilized satellites over many-year long time intervals. The cause of the cyclic variations of the proper rotation period of “Midas-7” satellite, which has been orbiting the Earth since 1963 at an altitude of 3700 km, have long been unclear. These variations could not be explained either by the influence of the terrestrial atmosphere and terrestrial magnetic field, or by solar activity. Based on the results of 40-year long observations of “Midas-4,” “Midas-6,”, and “Midas-7” satellites it was established that their proper rotation exhibits not only dissipative braking variations, but also long-period variations with the periods of 477 days (“Midas-4”), 466 days (“Midas-6”), and 346 days (“Midas-7”) with different amplitudes. These variations in the case of the above satellites have well-defined resonance nature. An explanation of the processes found is proposed based on the results of this study and simulations of the observed orbital dynamics of the satellites. Long-period variations of the proper spacecraft rotation arise as a result of the combined effect of the gravitational fields of the Earth, Moon, and Sun depending on the orientation of their orbital planes in space. The amplitudes of such variations is determined by the inclination of satellite orbits to the equator: the closer it is to the pole (i.e., to 90◦), the stronger the effect.

Probing Black Hole Magnetic Fields with QED

The effect of vacuum birefringence is one of the first predictions of quantum electrodynamics (QED): the presence of a charged Dirac field makes the vacuum birefringent when threaded by magnetic fields. This effect, extremely weak for terrestrial magnetic fields, becomes important for highly magnetized astrophysical objects, such as accreting black holes. In the X-ray regime, the polarization of photons traveling in the magnetosphere of a black hole is not frozen at emission but is changed by the local magnetic field. We show that, for photons traveling along the plane of the disk, where the field is expected to be partially organized, this results in a depolarization of the X-ray radiation. Because the amount of depolarization depends on the strength of the magnetic field, this effect can provide a way to probe the magnetic field in black-hole accretion disks and to study the role of magnetic fields in astrophysical accretion in general.

Study of Interplanetary and Geomagnetic Response of Filament Associated CMEs

AbstractIt has been established that Coronal Mass Ejections (CMEs) may have significant impact on terrestrial magnetic field and lead to space weather events. In the present study, we selected several CMEs which are associated with filament eruptions on the Sun. We attempt to identify the presence of filament material within ICME at 1AU. We discuss how different ICMEs associated with filaments lead to moderate or major geomagnetic activity on their arrival at the Earth. Our study also highlights the difficulties in identifying the filament material at 1AU within isolated and in interacting CMEs.

Approach to the Influence of the Terrestrial Magnetic Field on the Human Health

At the present times, people life and work into concrete buildings, and it has been reported that these structures decrease the earth’s magnetic field, what is associated with human health affections, which become these type of reinforced concrete constructions into a potentially factor of environmental contamination. In this paper the authors, with a simple procedure, determine the possible attenuation of the terrestrial magnetic field by different types of construction, and report the results. To study the possible relation among certain health sufferings, attributed to the lack of magnetic field, so called Syndrome of Magnetic Field Deficiency, a survey was carry out trying to establish the relationships: type of construction- health affection. Considering the results obtained, arguments are given in favor of the application of magnetic therapies in the rehabilitation of some health sufferings.