Component Of Geomagnetic Field Research Articles

Daily geomagnetic variations under variable IMF/solar conditions and their connection with underground conductivity changes in Japan

Fluctuations in Solar Wind (SW) and Interplanetary Magnetic Field (IMF) significantly affect the Geomagnetic Field (GF) measurements particularly during extreme space weather events. The current study investigates the variations of horizontal (H), vertical (Z) geomagnetic components under quiet and disturbed IMF and solar conditions as well as the effect of underground conductivity on the stationary geomagnetic measurements in Japan. Results of data analysis show that the response of the GF to IMF and solar parameters fluctuations is variable. The H- and Z-components were in good harmony with high visual correlation along a latitudinal profile across Japan during quiet times. On the other hand, during the disturbed times related to a Coronal Mass Ejection (CME) launched on 13 May 2005, the GF components varied with the disturbance of IMF and solar parameters. The H-components showed highly correlated variations with a significant reduction along the examined profile due to intensified ionospheric currents, while the Z-components recorded in the northern part of Japan showed abnormal daily variations pattern (positive daily variations) with an enhanced amplitude which is opposite to the normal behavior of daily variations recorded in the central and southern parts of Japan (negative daily variations). The observed enhanced and abnormal daily variation of Z-components in north Japan, which we consider a remarkable observation here, is possibly linked with underground conductivity anomaly in this region.

Characteristics of Electric Field Induced by Oscillating Metal Underwater Vehicle

To analyze the induced electric field characteristics generated by the rotation and shaking of underwater metal vehicles, a mathematical model of the induced electric field generated by the underwater metal vehicles was derived using Faraday’s electromagnetic induction law. A mathematical model of the induced electric field on the electrode pairs of metal vehicles shaking in different coordinate system planes was established through in-depth analysis. Based on this, a three-component output model of the induced electric field output by the three-axis sensor was obtained when the measurement system was shaking at all three angles. At a constant speed, the induced electric field interference output by the measurement system is a static signal. The value of the static electric field is proportional to the vehicle’s speed and the value of the geomagnetic field, and the value of each component is related to the direction of movement and the value of the geomagnetic field component. The simulation results show that when the navigation body is moving at a constant speed, the induced electric field is a static electric field with a magnitude of mV/m. In a stable state, the induced electric field noise generated by changes in pitch, roll, and heading sway is at the nV/m level and does not have a significant impact on detection. The correctness of the theoretical model has been verified through experiments on offshore speedboat platforms, and it is feasible to use metal navigation bodies for ship electric field detection.

Observations of Geomagnetic Crochet at High‐Latitudes Due To X1.5 Class Solar Flare on 3 July 2021

AbstractOn 3 July 2021, an X1.5 solar flare from the National Oceanic and Atmospheric Administration solar Active Region AR12838 (24°N, 88°W) occurred at 14:18 UT, peaked at 14:29 UT, and decayed at 14:34 UT. The study of this X1.5 solar flare is significant due to its unique geomagnetic crochet feature at high latitudes and its effective signature on Earth. The study examined X‐rays, the extreme ultraviolet spectrum, ionospheric equivalent current (IEC), and geomagnetic field components. The study reveals a sudden increase in IEC during the X1.5 flare episode, forming a zonal current region and producing a geomagnetic crochet signature in geomagnetic field components at high latitudes (50°–80°N) along the 11°–26°E longitude sector during the flare peak time. All three geomagnetic field components show different sensitivity to the solar flare effect (sfe), and the amplitude and phase of the geomagnetic crochet across latitudes (for a given longitude) are consistent with the variations in the IEC. The present study is the first to appraise geomagnetic crochets of low magnitude (8–40 nT) and short duration (10–15 min) at high latitudes, particularly in the polar cusp region, during the X‐class limb flare.

Earthquake forecast by imbalance machine learning using geophysical predictors

In the present paper we consider the earthquake forecast as a binary problem of machine learning on the imbalanced data base applied to five regions of Georgia. For the training we used geophysical data base collected in 2017-2021, namely, variations of statistical characteristics of geomagnetic field components, seismic activity, water level in deep boreholes and tides. In this version a new predictor – the weighted seismic activity for previous 5 days - – is added compared to the predictors’ list used in previous papers. Besides, the length of the used database is increased 3 times compared to the earlier results. As in the database the earthquakes of M > 3.5 are rare, the number of negative cases is large (there are many days without EQs of M > 3.5), meaning that there is a strong imbalance between positive and negative cases of the order of 1:20; we apply the specific methodology Matthews’ correlation coefficient (MCC) and F1 score to avoid the strong imbalance effect.

Variation of Total Electron Content over Nepal during Geomagnetic Storms: GPS Observations

Geomagnetic storms have very profound effects on the Total Electron Content (TEC) of the ionosphere. In order to investigate the equatorial and low-latitude ionospheric response to the geomagnetic storms of varying intensities, a detailed study of vertical TEC (VTEC) variations resulting from Global Positioning System (GPS) data acquired at four GPS stations in Nepal along 80°–90° E longitude and 26°–30° N latitude sector has been carried out in the present work. The results were analyzed with other favorable inducing factors (solar wind parameters and geomagnetic indices) affecting TEC to constrain the causative factor. Positive phases are observed for all the storms studied. During the severe geomagnetic activity, the deviation was ~18 TECU, while it was recorded ~12 TECU and ~8 TECU during moderate and minor geomagnetic activity, respectively. The Detrended Cross-Correlation Analysis (DXA) illustrates that the value of the hourly average VTEC of the BESI station was found to have a strong positive correlation with other stations in all types of storm events, indicating a similar response of all stations towards the space weather events. In addition, the correlation of VTEC with solar wind parameters and geomagnetic indices illustrated that the VTEC shows a strong positive association with solar wind velocity (Vsw) in all three geomagnetic events. In contrast, the correlation of plasma density (Nsw), interplanetary magnetic field (IMF-Bz), the symmetric horizontal component of geomagnetic field (SYM-H), and Geomagnetic Auroral Electrojet (AE) index with VTEC vary with the intensity of the storm. Overall results of the study have revealed the characteristic features of TEC variation over Nepal regions during magnetic storms, which validates earlier research on ionospheric responses to geomagnetic storms and theoretical assumptions.

On the Relationship between the Fractal Dimension of Geomagnetic Variations at Altay and the Space Weather Characteristics

The fractal dimension of geomagnetic field component variations (horizontal—H, vertical—Z and magnetic declination—D) at the Baigazan magnetic station at Russian Altay, for the period 2011–2013, were calculated using the Higuchi method. The daily variation of Higuchi Fractal Dimension (HFD) for the D, H, Z components of the geomagnetic field were investigated, and its contribution to the variability of HFD was found to be from 30 to 40 percent of the total variance. A correlation analysis of the fractal dimension of the variations of the D, H, Z components with the Auroral Electrojet (AE) index and solar wind characteristics was carried out. Negative correlations with logarithms of the AE-index, interplanetary magnetic field (IMF) strength and solar wind velocity were found. About 25 percent of the HFD variance is controlled by the variability of these characteristics. Pair and partial correlation coefficients for these parameters were calculated for every month of 2011–2013.

Геомагнитные эффекты взрывов сибирских метеоров

The geomagnetic effects of falling meteors have been known for a long time, but so far they have not received a complete theoretical explanation. The paper considers the response of the geomagnetic field to the destruction of meteors in Yakutia (March 4, 2014, 21:29 UT) and Khakassia (December 6, 2016) according to the Irkutsk magnetic observatory data of the Institute of Solar-Terrestrial Physics SB RAS. The analysis of variations in the geomagnetic field components showed that the passages and explosions of meteors were accompanied by the appearance of several groups of geomagnetic disturbances in the area of the Irkutsk magnetic observatory. Their appearance can be caused by the propagation of shock, internal gravity and magnetohydrodynamic waves formed as a result of the passages and destructions of meteors. The periods of these wave disturbances and the velocities of their propagation from the generation regions are estimated. It is noted that noticeable wave manifestations in the geomagnetic field give waves with a period of more than 10 minutes, i.e. having gravity modes.

Ionospheric irregularities observed during the geomagnetic storm of March 2015 and June 2015 over Ethiopia

In this paper we studied the occurrence of ionospheric irregularities over Ethiopia as the consequence of the intense geomagnetic storm of March 2015 and June 2015. Total Electron Content (TEC) data obtained from six Ethiopian GPS reciever stations and those data were used to derive the ionospheric irregularities proxy indices, e.g.,rate of change of TEC (ROT) and ROT index (ROTI). These indices were used to characterize the intensity of the fluctuation of total electron content. ROTI was used as a criterion of ionospheric irregularities that took place during the storm. These indices were characterized along side with the disturbance storm time (Dst),the Interplanetary Electric Field (IEFy) and the SYM-H index (high resolution version of Dst) from ground-based magnetometers to see the effect of geomagnetic storm on horizontal component of geomagnetic field. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) modulated the behaviour of irregularities during the initial and recovery phases of the geomagnetic storms. As a result,it was observed that the irregularities in the ionosphere of Ethiopia was in the range from weak to moderate. These irregularities generally occurred during the initial and recovery phases of the storm at all selected stations. The effect of electric field is found to depend on the local time at which the IMF Bz turned into southward. Therefore,east - west fluctuating Ey in March storm main phase is associated with suppression of irregularities in all stations and eastward Ey in the main phase of June 2015 is associated with small scale irregularity formation. The generation (inhibition) of irregularities is related to the effect of eastward (westward) storm time electric field disturbance dynamo electric fields and prompt penetration electric fields that created favourable (unfavourable) conditions for the generation of irregularities by uplifting (lowering) the F region.

Variation of the H Component of Geomagnetic Field: Relationship to the Ring and Field Aligned Currents

Variation of the H Component of Geomagnetic Field: Relationship to the Ring and Field Aligned Currents

Characterization of the geomagnetic H-component for a paired station in Africa

This scientific research investigates the quiet days variation, Sq(H) of H- component of geomagnetic field for the paired stations: Aswan (ASW: G.G.Lat.24.090N, G.G.Lon.32.890E and G.M.Lat.15.200, G.M.Lon.104.240),Durban (DRB: G.G.Lat.29.860S, G.G.Lon.31.020E and G.M.Lat.39.210, G.M.Lon.96.10) located along the 960 MM (magnetic meridian) using the ten international quietest days’ geomagnetic data from MAGDAS for the year 2009 (a low activity year).The study reveals that sq(H) shows predominantly the diurnal, monthly and seasonal variations of the geomagnetic H-component during the quiet days year round. With maximum amplitude of sq(H) in ASW and minimum in DRB. Meanwhile, the CEJ seen as negative depressions in the H-component of earth field at DRB are all salient physical processes in this study. Further data analysis also revealed many other interesting characteristics for the Sq(H) over African sector paired station. The conclusion drawn from the study shows that the geomagnetic field variations in the northern hemisphere are higher due to solar activities in the region. The Northern Hemisphere is tilted toward the sun, so this area of the Earth receives more direct sunlight during the day than the Southern Hemisphere does. The Southern Hemisphere, on the other hand, is tilted away from the sun and thus receives the sun's rays at an angle, which significantly explains why there is a consistent decrease when it reaches the Durban station (southern hemisphere station), hence the solar activity of the sun influences the Earth’s magnetic field, and the upper atmosphere(ionosphere).

Variation of the H component of geomagnetic field: relationship to the ring and field aligned currents

Variation of the H component of geomagnetic field: relationship to the ring and field aligned currents

Principal component analysis as a tool to extract Sq variation from the geomagnetic field observations: Conditions of applicability

We analyzed the applicability of the principal component analysis (PCA) as a tool to extract the Sq variation of the geomagnetic field (GMF) taking into account different geomagnetic field components, data measured at different levels of the solar and geomagnetic activity, data from different months.The validation of the method was performed with geomagnetic data obtained at the Coimbra Magnetic Observatory in Portugal (40° 13′ N, 8° 25.3′ W, 99 m a.s.l., IAGA code COI).GMF variations obtained with PCA were “classified” as SqPCA using reference series: (1) obtained from the observational data (SqIQD), (2) simulated by ionospheric field models.While our results show that both the data-based and model-based reference series can be used, the DIFI3 model performs better as a reference series for GMF at middle latitudes.We also recommend to estimate the similarity of the series with a metric that account for possible local stretching/compressing of the compared series, for example, the dynamic time warping (DTW) distance.Since the validation of the method was performed on the geomagnetic series obtained at a mid-latitudinal European observatory, we recommend performing additional tests when applying this method to data obtained in other regions/latitudes.•For the Y and Z components of the geomagnetic field PCA can be used to extract Sq variations from the observations without any additional procedures and SqPCA is equals to PC1.•For the X component PCA can be used to extract Sq variation from the observations of the X component, but further analysis, for example, a comparison to a set of reference curves either obtained from the data analysis or generated using models, is always needed to classify PCs of the X component.•We recommend to use data generated by DIFI-class models as reference series and the dtw metric (dynamic time warping distance) to classify SqPCA.

Исследование отклика среднеширотной ионосферы Северного полушария на магнитные бури в марте 2012

We have studied variations in ionospheric and geomagnetic parameters in the Northern Hemisphere during a series of magnetic storms in March 2012 by analyzing data from the Eurasian mid-latitude ionosonde chain, mid- and high-latitude chains of magnetometers of the global network INTERMAGNET. We have confirmed manifestations of the longitude inhomogeneity of ionospheric effects, which is associated with the irregular structure of the longitudinal variability of geomagnetic field components. The complex physics of the long magnetically disturbed period in March 2012 with switching between positive and negative phases of the ionospheric storm in the same period of the magnetic storm for different spatial regions is emphasized. The change in the effects of the ionospheric storm during this period might have been associated with the superposition in the mid-latitude region of the competing processes affecting the ionospheric ionization whose sources were in the auroral and equatorial ionosphere. We have compared the scenarios for the development of ionospheric disturbances under equinox conditions during magnetic storms in March 2012, October 2016, and March 2015.

Studying the response of the mid-latitude ionosphere of the Northern Hemisphere to magnetic storms in March 2012

We have studied variations in ionospheric and geomagnetic parameters in the Northern Hemisphere during a series of magnetic storms in March 2012 by analyzing data from the Eurasian mid-latitude ionosonde chain, mid- and high-latitude chains of magnetometers of the global network INTERMAGNET. We have confirmed manifestations of the longitude inhomogeneity of ionospheric effects, which is associated with the irregular structure of the longitudinal variability of geomagnetic field components. The complex physics of the long magnetically disturbed period in March 2012 with switching between positive and negative phases of the ionospheric storm in the same period of the magnetic storm for different spatial regions is emphasized. The change in the effects of the ionospheric storm during this period might have been associated with the superposition in the mid-latitude region of the competing processes affecting the ionospheric ionization whose sources were in the auroral and equatorial ionosphere. We have compared the scenarios for the development of ionospheric disturbances under equinox conditions during magnetic storms in March 2012, October 2016, and March 2015.

Seasonal Variabilities of Geomagnetic Field Components and Their Inter-Relationships along African Low Latitudes

Seasonal Variabilities of Geomagnetic Field Components and Their Inter-Relationships along African Low Latitudes

Structure of groups of eigenfrequencies in spectra of geomagnetic pulsations in the nightside magnetosphere

Using a new method of correlation function for amplitude and phase fluctuations (APCF), records of geomagnetic field component fluctuations (observatories Mondy and Borok) have been processed for a number of hour zones of the nightside magnetosphere. This method is meant to detect groups of equidistant frequencies inside the spectrum of source signal and also to measure a difference between two neighbor frequencies in each of these groups.

Структура групп собственных частот в спектрах геомагнитных пульсаций ночной стороны магнитосферы

Using a new method of correlation function for amplitude and phase fluctuations (APCF), records of geomagnetic field component fluctuations (observatories Mondy and Borok) have been processed for a number of hour zones of the nightside magnetosphere. This method is meant to detect groups of equidistant frequencies inside the spectrum of source signal and also to measure a difference between two neighbor frequencies in each of these groups.
 The groups of equidistant frequencies in broadband spectra of these fluctuations are shown to depend on eigenfrequencies of the 2D Alfvén wave resonator, just as for dayside fluctuations [Polyakov, 2018]. An empirical relation has been found between a combination of parameters of this resonator and local time. The similarity between structural elements in the final products of processing of Alfvén fluctuation N-S and E-W components for almost all hour zones clearly indicates the reliability of the results of the APCF method in processing any broadband signals.

Alex magnetometer and telluric station in Egypt: First results on pulsation analysis

This study presents the first results of a newly installed ground-based station Alex Magnetometer and Telluric Station (AMTS) located in Alexandria governorate in Egypt (geographic coordinate: 30° 51.68′ N, 29° 33.67′ E). The station consists of a fluxgate digital magnetometer and a two-channel digital Long Period Telluric Recorder (LPTR). The station commenced operation on October 12th, 2021, by providing real-time data of the geoelectric and geomagnetic field components. Despite the low solar activity, the AMTS detected several signatures of geomagnetic storms. An illustrative case study was conducted on the strong geomagnetic storm of November 4th, 2021. The magnetic field components recorded by the station demonstrated a prompt increase synchronized with the Sudden Storm Commencement (SSC) captured by the ACE satellite arriving at 19:42 UT on November 3rd, 2021. The three geomagnetic field components recorded by the AMTS during the storm were consistent with the nearby INTERMAGNET stations. The digital fluxgate magnetometer’s high sampling frequency (400 Hz) and the LPTR with a sampling frequency (1 Hz), allowed us to capture all ULF pulsations. The structural pearl-shaped Pc1 pulsation was obtained in all phases of the geomagnetic storm with repetitive oscillations in the main storm phase. The wavelet analysis of micropulsations recorded at AMTS showed a high coherence with the nearby-four INTERMAGNET stations demonstrating high data integrity and reliability. The magnetometer and telluric measurements at the AMTS will fill the data gap in the northern section of Africa and allow us to study geoelectric and geomagnetic micropulsations in the region.

Fractal Dimension Analysis of Earth Magnetic Field during 26 August 2018 Geomagnetic Storm

We analyse the fractal nature of geomagnetic field northward and eastward horizontal components with 1 min resolution measured by the four stations Belsk, Hel, Sodankylä and Hornsund during the period of 22 August–1 September, when the 26 August 2018 geomagnetic storm appeared. To reveal and to quantitatively describe the fractal scaling of the considered data, three selected methods, structure function scaling, Higuchi, and detrended fluctuation analysis are applied. The obtained results show temporal variation of the fractal dimension of geomagnetic field components, revealing differences between their irregularity (complexity). The values of fractal dimension seem to be sensitive to the physical conditions connected with the interplanetary shock, the coronal mass ejection, the corotating interaction region, and the high-speed stream passage during the storm development. Especially, just after interplanetary shock occurrence, a decrease in the fractal dimension for all stations is observed, not straightforwardly visible in the geomagnetic field components data.

ULF Fluctuation of Low‐Latitude Ionospheric Electric Fields During Sudden Commencements

AbstractWe use the C/NOFS satellite observations to provide the direct evidence for ultra‐low‐frequency (ULF) fluctuations in the low‐latitude ionospheric electric field during the sudden commencement (SC) on 8 March 2012. The meridional plasma drift shows a sudden downward motion with a large amplitude after SC onset. This initial westward electric field signature is followed by ULF fluctuations with periods of 28–100 s. Further, C/NOFS observations show that the ionospheric zonal electric field and compressional component of geomagnetic field present the similar ULF fluctuations with a ∼90° phase difference, indicating the existence of a standing compressional mode wave. The fluctuations in the ionospheric electric field and horizontal component of the geomagnetic field on the ground also exhibit a high correlation and the frequency of the ground‐based geomagnetic field shows no dependence with latitudes. These results suggest that the ULF waves in the ionospheric electric field may be associated with a cavity mode. We also show the ULF waves in ionospheric electric fields in other cases. The ULF wave electric fields provide important information on the ionospheric studies and ionosphere‐magnetosphere coupling in low latitudes.