Geomagnetic Maps Research Articles

Mapping a Magnetic Superstorm: March 1989 Geoelectric Hazards and Impacts on United States Power Systems

AbstractA study is made of the relations between geomagnetic and geoelectric field variation, Earth‐surface impedance, and operational interference (“anomalies”) experienced on electric‐power systems across the contiguous United States during the 13–14 March, 1989, magnetic storm. For this, a 1‐min‐resolution sequence of geomagnetic field maps is constructed from magnetometer time series acquired at ground‐based observatories. Induced geoelectric field maps are calculated by convolving the geomagnetic maps with magnetotelluric impedance tensors. During the storm, anomalies were concentrated where the lithosphere is electrically resistive, and when and where geoelectric field amplitudes were high. This was particularly true in the Mid‐Atlantic, Northeast, and the upper Midwest. Few anomalies were experienced in other parts of the Midwest and across much of the West, where the lithosphere is more conductive, and when and where geoelectric field amplitudes were low. Peak 1‐min‐resolution geoelectric field amplitude ranged from 21.66 V/km in Maine and 19.02 V/km in Virginia to <0.02 V/km in Idaho. Latitude‐dependent organization of geoelectric hazards by auroral‐zone electrojet currents is detectable, but it is much weaker than geographic organization due to surface impedance. Hazardous geoelectric fields were induced during different storm phases, at different local times, and, by inference, by a variety of ionospheric currents. Compared to geoelectric field amplitudes realized across the United States during March 1989, hazard maps used by utility companies to estimate systems exposure have much less geographic detail and a much smaller maximum‐to‐minimum range in geoelectric field amplitude. Future research would benefit from denser geomagnetic monitoring, additional magnetotelluric surveying, and access to power‐system impact data.

No apparent effect of a magnetic pulse on free-flight behaviour in northern wheatears (Oenanthe oenanthe) at a stopover site.

Naïve migrants reach their wintering grounds following a clock-and-compass strategy. During these inaugural migrations, birds internalise, among others, cues from the Earth's magnetic field to create a geomagnetic map, with which they navigate to destinations familiar to them on subsequent migrations. Geomagnetic map cues are thought to be sensed by a magnetic-particle-based receptor, which can be specifically affected by a magnetic pulse. Indeed, the orientation of experienced but not naïve birds was compromised after magnetic pulsing, indicating geomagnetic map use. Little is known about the importance of this putative magnetoreceptor for navigation and decision-making in free-flying migrants. Therefore, we studied in unprecedented detail how a magnetic pulse would affect departure probability, nocturnal departure timing, departure direction and consistency in flight direction over 50–100 km in experienced and naïve long-distant migrant songbirds using a large-scale radio-tracking system. Contrary to our expectations and despite a high sample size (ntotal = 137) for a free-flight study, we found no significant after-effect of the magnetic pulse on the migratory traits, suggesting the geomagnetic map is not essential for the intermediate autumn migration phase. These findings warrant re-thinking about perception and use of geomagnetic maps for migratory decisions within a sensory and ecological context.

Indication of a ship location by the Earth’s geomagnetic field

The present study focuses on the need to increase the number of methods for indicating a ship location in traffic conditions on routes with heavy shipping, as well as during navigation in hard hydrometeorological conditions. The research purpose is to increase the level of safety and accuracy of ship navigation and effectively meet the requirements in the field of navigation safety and environmental protection. The issue of navigating through physical fields has a wide range of unresolved tasks despite the previously conducted studies. These tasks include investigation of geomagnetic sensors and their relationship to geomagnetic maps, as well as magnetic compasses and ways to improve them by using magnetometers and eliminating errors caused by rotation of the magnetic needle.

An Intelligent Geomagnetic Search Navigation Method Based on Evolutionary Gradient Strategy

Currently, most of the geomagnetic navigation methods are matching navigation algorithms, which require the geomagnetic maps retrieved in advance, and saved in a database. However, there are a great number of unknown environments exist worldwide that limit the extensive application of the geomagnetic matching method in practice. In this paper, an intelligent geomagnetic search navigation method based on the evolutionary gradient search (EGS) algorithm is proposed. The performance of the search and navigation method is analysed with both simulated and real geomagnetic data. And the conclusion is that compared with other intelligent search strategies, the proposed algorithm has better navigation performance with less average navigation error, 161m, which is equivalent to the most traditional geomagnetic matching algorithms. Thus, the EGS algorithm proposed in this paper can effectively improve the performance of geomagnetic navigation without prior geomagnetic information.

КОНФИГУРАЦИИ УКРЕПЛЕННЫХ ПОСЕЛЕНИЙ СИНТАШТИНСКО-ПЕТРОВСКОГО ТИПА: ФОРМЫ, РАЗМЕРЫ, ТРАНСФОРМАЦИИ

The article aims to analyze the configurations of fortified settlements of the Sintashta-Petrovka type (SPT settlements). Sources of information about the configurations are the results of remote research (aerial photographs, geomagnetic maps, topographic maps) and data from archaeological excavations. The study of configurations is one of the aspects of settlement archaeology at the level of research of the structure of the whole settlement. The article summarizes and compares the characteristics of forms, layouts, sizes, variants of transformations. The forms of SPT settlements can be divided into two types: rounded, with a radial arrangement of rows of dwellings, and subrectangular, with a linear arrangement. Eight sites are classified as rounded, sixteen are subrectangular. In the forms of many settlements there are mixed signs that emphasize the common architectural tradition: rounded settlements have separate straightened segments and straight rows of buildings, and subrectangular ones have rounded bends of building lines and rounded corner sections. In summarizing the size indicators, small, medium and large settlements were identified. The small ones have an area from 6 to 13 m2; thousand nine sites – subrectangular, with two rows of dwellings, and rounded, with one ring of buildings – are small. The small m2. settlements have about 20 to 30 buildings. The number of medium settlements is also nine, their area is from 15 to 21 thousand Most medium-sized sites are either subrectangular, with four rows of buildings, or rounded, with two rings of buildings. The medium m2. sized settlements have about 40 to 60 buildings. There are six large settlements; their area is 23 to 32 thousand Two of the large settlements are oval, four subrectangular, with traces of significant rearrangements. Due to the small volume of field research, it is difficult to estimate the number of dwellings in large settlements. The generalization of the remote data and the results of the excavations allows the author to propose a scheme of transformations of the SPT settlements. The structural component of their configurations is a row of closely spaced dwellings, enclosed by a line of fortifications. Several rows, most often two or four, oriented linearly or radially, form the inner space of the closed fortified settlement. While the fortified settlements functioned, they were restructured, with preservation of the general principles of regularity and isolation of the living environment. There are three main scenarios for rebuilding: the completion of rows to the early section, the overlapping of fortified villages, the reduction of the area of a fortified settlement. The final stage of the life of settlements is associated with the gradual abandonment of the cramped and closed configurations. The Srubnaya-Alakul settlements, successors of the SPT settlements, use more spacious, dispersed layouts, with partial preservation of the tradition of building rows of closely spaced dwellings and with refusal to build fortifications.

Spatial distribution of historical geomagnetic measurements in Mexico

The spatial analysis of the geomagnetic field through time allows obtaining some crucial information about the evolution of the Earth's deep interiors and outer core-mantle conditions. Apart from discrete palaeomagnetic and archaeomagnetic records, the direct magnetic measurements of declination, inclination and intensity may largely contribute to unearthing historical geomagnetic distribution maps. The available historical data in Mexico (https://doi.org/10.1016/j.pepi.2020.106433, Physics of the Earth and Planetary Interiors 300, 2020, 106433) may be divided into two large groups: Data from the different observatories in Mexico between 1879 and 2018 (139 years); and the historical values of magnetic cartography accumulated in several documents between 1587 and 2018 (431 years). Part of the specific objectives of magnetic mapping in Mexico is the estimation and analysis of the local and global behavior of the geomagnetic phenomena. The historical geomagnetic record gathers data on the declination, inclination and total geomagnetic intensity obtained initially by sailors that represent a unique scientific heritage in Latin America.

Depth geological relations of the wider area of Belgrade - based on the wells and geophysical data

The subject work covers the Belgrade wider area with a total area of about 2,000 km2. The authors integrated the principal geological and geophysical data provided by surface works and multidisciplinary elements from the fifty-two wells with depths between 33 and 2,733 m. Explicit paleontological findings of specialized analytists with determinations of macro- and microfauna and flora are presented both from Neogene formations and the older basinal floor. In addition to conventional petrological descriptions of rocks, microscopic determinations of intrusive and extrusive magmatites were also cited. From the enclosed basin space, the mineralization of deep aquifers is also correlative positioned. From the geophysical data for wells deeper than 400 m, records of well logging measurements were used, with markers based on which valid stratigraphic delimitations were made. Seismic survey sections were the basis for spatial shaping of Neogene sedimentation and basin floor configuration. For in-depth geological interpretations, published and repository gravimetric and geomagnetic maps of different sizes and years were consulted. The authors focused primarily on factometric indicators without entering into variable and debatable theoretical schematizations, especially orogenically complex of subbasin tectonics, in dissonant relations with the younger disjunctive shaped configuration which is visually shown in the reference cross-sections both vertically and laterally

Real-Time Recursive Fingerprint Radio Map Creation Algorithm Combining Wi-Fi and Geomagnetism.

Fingerprint is a typical indoor-positioning algorithm, which measures the strength of wireless signals and creates a radio map. Using this radio map, the position is estimated through comparisons with the received signal strength measured in real-time. The radio map has a direct effect on the positioning performance; therefore, it should be designed accurately and managed efficiently, according to the type of wireless signal, amount of space, and wireless-signal density. This paper proposes a real-time recursive radio map creation algorithm that combines Wi-Fi and geomagnetism. The proposed method automatically recreates the radio map using geomagnetic radio-map dual processing (GRDP), which reduces the time required to create it. It also reduces the size of the radio map by actively optimizing its dimensions using an entropy-based minimum description length principle (MDLP) method. Experimental results in an actual building show that the proposed system exhibits similar map creation time as a system using a Wi-Fi–based radio map. Geomagnetic radio maps exhibiting over 80% positioning accuracy were created, and the dimensions of the radio map that combined the two signals were found to be reduced by 23.81%, compared to the initially prepared radio map. The dimensions vary according to the wireless signal state, and are automatically reduced in different environments.

Indonesian Geomagnetic Maps for Epoch 2015.0 to cover of Indonesian Regions

In compliance with the resolutions of IAGA (International Association of Geomagnetism and Aeronomy), Since 1960’s, every five years BMKG or Meteorology, Climatology and Geophysics Agency of Indonesia made geomagnetic field maps based on actual measurements in 53 repeat stations. It’s the map for more accurate result of Geomagnetic maps Epoch 2015.0, the number of repeat stations has been increased to 68 locations. Analysis data was conducted by spatial analyses using collocated co-kriging and kriging with external drift to map the observation data in five components, such as Declination (D), Inclination (I), Vertical (Z), Horizontal (H), and Total Geomagnetic Field (F). The data reduction used one permanent observatory i.e., Kupang Geophysical Observatory, as a reference standard. The results of this Geomagnetic Maps, that the contour lines of Indonesian geomagnetic declination in range -1 to 4.5 degree, Inclination component are -5 to -37 degree, Vertical component are -4000 to -28000 nT, Horizontal component are 36000 to 42000 nT, and Total Geomagnetic Field are 39000 to 46000 nT. In conclusion, Indonesian Geomagnetic Maps for Epoch 2015.0 can be used to compute geomagnetic data around Indonesian regions until next 5 years.

The Egyptian geomagnetic reference field to the Epoch, 2010.0

The present work is a compilation of two tasks within the frame of the project “Geomagnetic Survey & Detailed Geomagnetic Measurements within the Egyptian Territory” funded by the “Science and Technology Development Fund agency (STDF)”. The National Research Institute of Astronomy and Geophysics (NRIAG), has conducted a new extensive land geomagnetic survey that covers the whole Egyptian territory. The field measurements have been done at 3212 points along all the asphalted roads, defined tracks, and ill-defined tracks in Egypt; with total length of 11,586km. In the present work, the measurements cover for the first time new areas as: the southern eastern borders of Egypt including Halayeb and Shlatin, the Quattara depresion in the western desert, and the new roads between Farafra and Baharia oasis. Also marine geomagnetic survey have been applied for the first time in Naser lake.Misallat and Abu-Simble geomagnetic observatories have been used to reduce the field data to the Epoch 2010. During the field measurements, whenever possible, the old stations occupied by the previous observers have been re-occupied to determine the secular variations at these points.The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF) and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF) 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF) 2010 is indicated.

Theoretically possible spatial accuracy of geomagnetic maps used by migrating animals.

Many migrating animals, belonging to different taxa, annually move across the globe and cover hundreds and thousands of kilometres. Many of them are able to show site fidelity, i.e. to return to relatively small migratory targets, from distant areas located beyond the possible range of direct sensory perception. One widely debated possibility of how they do it is the use of a magnetic map, based on the dependence of parameters of the geomagnetic field (total field intensity and inclination) on geographical coordinates. We analysed temporal fluctuations of the geomagnetic field intensity as recorded by three geomagnetic observatories located in Europe within the route of many avian migrants, to study the highest theoretically possible spatial resolution of the putative map. If migratory birds measure total field intensity perfectly and take the time of day into account, in northern Europe 81% of them may return to a strip of land of 43 km in width along one of coordinates, whereas in more southern areas such a strip may be narrower than 10 km. However, if measurements are performed with an error of 0.1%, the strip width is increased by approximately 40 km, so that in spring migrating birds are able to return to within 90 km of their intended goal. In this case, migrating birds would probably need another navigation system, e.g. an olfactory map, intermediate between the large-scale geomagnetic map and the local landscape cues, to locate their goal to within several kilometres.

Global statistical maps of extreme‐event magnetic observatory 1 min first differences in horizontal intensity

AbstractAnalysis is made of the long‐term statistics of three different measures of ground level, storm time geomagnetic activity: instantaneous 1 min first differences in horizontal intensity ΔBh, the root‐mean‐square of 10 consecutive 1 min differences S, and the ramp change R over 10 min. Geomagnetic latitude maps of the cumulative exceedances of these three quantities are constructed, giving the threshold (nT/min) for which activity within a 24 h period can be expected to occur once per year, decade, and century. Specifically, at geomagnetic 55°, we estimate once‐per‐century ΔBh, S, and R exceedances and a site‐to‐site, proportional, 1 standard deviation range [1 σ, lower and upper] to be, respectively, 1000, [690, 1450]; 500, [350, 720]; and 200, [140, 280] nT/min. At 40°, we estimate once‐per‐century ΔBh, S, and R exceedances and 1 σ values to be 200, [140, 290]; 100, [70, 140]; and 40, [30, 60] nT/min.

History of the Munich–Maisach–Fürstenfeldbruck Geomagnetic Observatory

Abstract. The Munich–Maisach–Fürstenfeldbruck Geomagnetic Observatory is one of the observatories with the longest recordings of the geomagnetic field. It started with hourly measurements on 1 August 1840. The founder of the observatory in Munich was Johann von Lamont (1805–1879), the Director of the Royal Bavarian Astronomical Observatory. He had been stimulated to build his own observatory by the initiative of the Göttingen Magnetic Union founded in 1834 by Alexander von Humboldt (1769–1859) and Carl Friedrich Gauss (1777–1855). Before 1840 fewer than five observatories existed; the most prominent ones were those in London and Paris. At the beginning Lamont used equipment delivered by Gauss in Göttingen, but soon started to build instruments of his own design. Among them was a nonmagnetic theodolite which allowed precise geomagnetic measurements to be made also in the field. During the 1850s Lamont carried out geomagnetic surveys and produced geomagnetic maps for Germany and many other European countries. At the end of the nineteenth century accurate geomagnetic measurements in Munich became more and more disturbed by the magnetic stray fields from electric tramways and industry. During this period the quality of the data suffered and the measurements had to be interrupted several times. After a provisional solution in Maisach, a village 25 km west of Munich, a final solution could be found in the vicinity of the nearby city of Fürstenfeldbruck. Here the measurements started again on 1 January 1939. Since the 1980s the observatory has been part of INTERMAGNET, an organization providing almost real-time geomagnetic data of the highest quality.

Croatian geomagnetic field maps for 2008.5 epoch

<p>The status of the Croatian Geomagnetic Repeat Stations Network (CGRSN) and Croatian Geomagnetic Network for Field Mapping (CGNFM), completed in 2010, was described. Standard and new survey practices as well as reduction techniques were presented. The CGRSN data reduced in reference to the L'Aquila (AQU), Grocka (GCK) and Tihany (THY) observatories using weighted averages were given for the epoch 2008.5. Detailed pictures of Dalmatia's geomagnetic field of 2008.5 and the corresponding anomaly, obtained from the CGNFM data were shown.</p>

Magnetic ground survey of Slovakia for the 2007.5 epoch – accuracy of geomagnetic elements distribution maps

Abstract Magnetic ground or repeat station surveys are performed to determine the geomagnetic field (GMF) spatial distribution, which is of great importance for scientific purposes as well as for many applications, for instance the aerial navigation. In for the information about the GMF distribution to be complete, the accuracy of the geomagnetic maps need to be known. It is a custom in the papers dealing with magnetic surveys that the precision of the instruments employed for the measurements are listed there. However, such information is not sufficient to answer the question about the quality of the geomagnetic maps because our experience shows that the spatial variations at a distance of several kilometers often exceed the precisions of the instruments. In the paper we proposed a simple method for the evaluation of the accuracy of the GMF distribution maps. We applied it to the maps which were the results of the magnetic ground survey carried out in Slovakia in the 2007.5 epoch. The method is based on the following procedure which is accomplished for each observation point of the magnetic ground survey network: A single point drops out of the data base, then the map is generated in a standard way, whereupon the observed value of the geomagnetic element for the dropped out observation point is compared with the value of the geomagnetic element which is determined from the map. Thus the image of the accuracy of the complete map can be tagged together for the surveyed territory

Positioning performance evaluation of magnetic contour matching under different accuracy of sensor

The accuracy of geomagnetic reference map, geomagnetic sensor, and inertial navigation system is the key factor which affects the reliability of magnetic contour matching (MAGCOM) system. In order to improve the reliability of MAGCOM, the influence of the sensor's accuracy on the matching success rate has been studied. For different geomagnetic reference maps, the factors and their physical mechanism affecting matching success rate have been analyzed, the factors are geomagnetic sensor error, velocity error, and heading angle error. The error range of sensors was determined by the simulation computing which was based on a practical system and a simulation experimentation was implemented by using the geomagnetic reference map. The simulation results show that MAGCOM can allow the velocity error 0.14 m/s, the heading angle error 0.6 and the standard deviation of geomagnetic sensor noise 11 nT, when the matching success rate is 90%.

Navigation and Positioning by Using the Insufficient Geomagnetic Components

Geomagnetic field information of the vehicle contains abundant positional information, so the positional information can be derived from the geomagnetic observational value. Firstly, base on the analysis of geomagnetic maps of southeast China, the least square algorithm is used for modeling the local geomagnetism on WMM2010(world magnetic model)database. Then, the optimal positional model can be derived. The simulation has been done, from the simulation results we can see that the mean- squared error of the model in latitude and longitude are about 0.7062 sea mile and 1.8735 sea mile respectively. At last, according to the shortcoming of geomagnetic course system such as costing more time and money in calibration error, the partial geomagnetic field model is applied on correcting the compass variation. The analysis of simulation result indicates that the accuracy has been significantly improved.

Spatiotemporal sampling of Sq+-induced geomagnetic responses at LEO satellite altitude for a radially conductive Earth

SUMMARY A new simulation tool is introduced for extracting Earth conductivity information from geomagnetic satellites in low Earth orbit (LEO) such as CHAMP, Swarm and potential follow-on missions. Theoretical reconstruction of spherical harmonic spectra of global universal time (UT) geomagnetic field maps is analysed. An idealized regular solar daily variation field is assumed, along with its induced counterpart from a radially stratified Earth. Solar-quiet (Sq) spectra can be reliably reconstructed from discrete time-series of measurements sampled daily within a fixed UT window. A single LEO satellite should be in orbit for at least 1 yr under quiet-time conditions to ensure accurate spectral reconstruction of an Sq geomagnetic spectrum. The length of the daily sampling window and random day-to-day variability in the Sq source strength have only minor effects on spectral reconstruction. The shape of the spectra, and spectral ratios, are independent of radial mantle conductivity. Further research employing 3-D forward modelling of induction in a laterally heterogeneous earth, with more realistic and complete external source descriptions, is advocated. The new simulation tool should prove valuable to planners of future multisatellite geomagnetic missions, as well as scientists interested in analysing and interpreting satellite induction signals.

Integration of Landsat imagery interpretation and geomagentic data on verification of deep‐seated transverse fault lineaments in SE Zagros, Iran

In this paper, Landsat images are used in the mapping of transverse fault lineaments in Zagros, Iran, and the origin of the fault lineaments as the result of basement reactivation faults is examined using geomagnetic maps. The area under investigation is located in the SE part of the Zagros Fold Belt (ZFB) and was affected by influence of concealed faults, or fault lineaments, during the late Alpine Zagros orogeny. Image interpretation of geological structures such as curvilinear geometry of fold hinges, en echelon pattern of surficial lineaments and younger folds, and breached salt plugs, has been used to map the fault lineaments. Two sets of strike‐lateral transverse fault lineaments have been detected. The first set, NW‐trending, was identified by right lateral curved geometry of the main fold hinges, generation of younger folds, and en echelon pattern of surficial lineaments. The second set, NE‐trending, was verified based on left lateral displacement of the structures and alignment of salt plugs pierced anticline hinges. The placement of Upper Proterozoic salt plugs on the surface along the fault lineaments, together with their correlation with the magnetic‐driven lineaments, implies that the fault lineaments have a basement origin. The trend of these fault lineaments can be correlated with the trend of basement faults in the northern margin of the Arabian plate. The key result of this study is that the fault lineaments identified by integration of remotely sensed data and geomagnetic maps are generated as first order wrench faults by reactivation of the N–S‐trending basement faults. The thick Hormoz Salt formations overlaying the basement do not allow the fault lineaments to emerge at the surface. Therefore, they can be mapped through regional remote sensing and their basement origin can only be recognized by their correlation with magnetic faults. It is also concluded that satellite imagery can greatly contribute to the structural mapping of the ZFB and is therefore a valuable aid for oil and gas exploration in analogous tectonic environments.

Study of Geomagnetic Field Models of the Qinghai‐Xizang (Tibetan) Plateau

AbstractBased on three‐component absolute geomagnetic survey data and by use of the Taylor polynomial method and the spherical cap harmonic analysis method, the Taylor polynomial models of the geomagnetic field (X, Y and Z) and spherical cap harmonic models of the geomagnetic residual field (∆X,∆Y and ∆Z) over the Qinghai‐Xizang plateau are calculated, and corresponding theoretical geomagnetic maps are also constructed. The effects of geomagnetic anomalous stations on the geomagnetic field model are analysed, a comparison between the polynomial model and the spherical cap harmonic model of the geomagnetic field is carried out, and the boundary effects of the geomagnetic field model are discussed, too.