Geomagnetic Disturbances Research Articles

Impact of Geomagnetically Induced Current on Power Grid Resiliency Under Extreme Geomagnetic Disturbance

Impact of Geomagnetically Induced Current on Power Grid Resiliency Under Extreme Geomagnetic Disturbance

Pheromone Trap Catch of Fruit Pest Moths Influenced by the Geomagnetic Disturbance Storm Time (Dst)

Pheromone Trap Catch of Fruit Pest Moths Influenced by the Geomagnetic Disturbance Storm Time (Dst)

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.

Simultaneous Mesoscale Polar Cusp Field‐Aligned Currents Measured on Mid‐ and Low‐Altitude Satellites

AbstractUsing a conjunction of Cluster in the mid‐altitude dayside magnetosphere and Swarm in the low‐altitude ionosphere, we show, by employing multi‐spacecraft analysis, that matched, strong magnetic perturbations and the corresponding mesoscale field‐aligned current (FAC) structures are measured in the high latitude polar cusp region during the 7 October 2015 storm. Two pairs of opposite (positive/negative) FACs are observed by both Cluster and Swarm, which may relate to pulsed magnetic reconnection at the dayside magnetopause. Furthermore, the current intensity of these matched FACs decreases from high to low latitude, consistent with the time elapsed since reconnection. Corresponding geomagnetic disturbances are also observed by ground stations. Our observations provide direct evidence for the coupling of mesoscale FACs between the magnetosphere, ionosphere and ground in the polar cusp region, where the signatures are driven in this case by conditions suitable for inducing reconnection.

Evaluation of the Dix Scaling Factor During Geomagnetically Disturbed Periods Over South America

In this work, we present a study of the Total Electronic Content (TEC) spatiotemporal variability during geomagnetically disturbed periods over South America. For this, we evaluated the Disturbance Ionosphere indeX (DIX) scaling factor (β coefficient) for different magnetic dip angles and seasons. In this context, the β values are given in TEC units (TECU) and correspond to a latitudinal-dependent factor used to normalize the DIX output into a scale from 0 to 5. Thus, we selected thirteen magnetic storm events between 2013 and 2017, subdivided into seven moderate, four intense, and two extreme magnetic storms. The results showed that the β coefficient latitudinal variation is characterized by two asymmetric crests concerning the magnetic equator. This suggests the presence of transequatorial thermospheric wind's effects on the ionosphere's plasma distribution. Additionally, we have observed that the crests occur close to the magnetic equator during the winter and autumn and at higher latitudes during summer and spring. Additionally, we have noticed a drastic decrease in the daily highest β-values before the Storm Sudden Commencement (SSC) stage of the studied events and during the magnetic storm recovery phase. This behavior highlights the expected scenario of quiet conditions with no TEC disturbance.

Variation of Total Electron Content in the Quiet and Disturbed Period and Their Correlation with Solar Wind Parameters

Total electron content and electron density are the fundamental parameters that determine the main properties of the ionosphere. We have observed variation of Global Positioning System (GPS) derived Vertical Total Electron Content (VTEC) on three different geomagnetic events. The observed VTEC data is recorded from four GPS stations at different locations (87.26°E, 26.48°N); (85.79°E, 27.87°N); (84.57°E, 28.17°N), and (86.70°E, 27.81°N). To determine the severity of storms, we analysed the north-south component of interplanetary magnetic field (IMF-Bz), solar wind parameters- solar wind speed (Vsw) and solar wind dynamic pressure (Psw) ,and geomagnetic indices- Dst index, Kp index and Auroral Electrojet (AE). For all the studied event days, we observed intensified VTEC on geomagnetically disturbed days over quiet days. The VTEC enhancement was significantly high on the severely disturbed day, followed by the moderate storm and the minor storm.The study made to observe association of VTEC with different interplanetary and geomagnetic indices shows that during all studied event days, VTEC enhancement is positively correlated with Vsw, Psw, AE and Kp with cross-correlation coefficient above 0.8 at zero time lag and strong negative correlation with Dst index. In contrast, the correlation of IMF-Bz vary with the intensity of storm. Our finding show a significant variation in VTEC during the geomagnetic disturbances, supporting previous studies on ionospheric responses to geomagnetic storms as well as theoretical assumptions.

ОЦЕНКА ВЗАИМОСВЯЗИ МЕЖДУ ВОЗМУЩЕНИЯМИ ГЕОМАГНИТНОГО ФОНА И ОТВЕТОМ СО СТОРОНЫ СЕРДЕЧНО-СОСУДИСТОЙ СИСТЕМЫ С ИСПОЛЬЗОВАНИЕМ СТАНДАРТНЫХ СТАТИСТИЧЕСКИХ РЕШЕНИЙ

The purpose of this work is to present the mechanism of statistical data processing necessary to assess the sensitivity of the human cardiovascular system to geomagnetic disturbances. However, the approach proposed by us can be used not only to identify the relationship between the daily level of geomagnetic disturbance and the performance of the cardiovascular system, but also to solve other similar problems. Materials and methods, namely, standard statistical techniques, such as χ2, and Fisher’s exact test, allowed us to find the solution necessary to establish the relationship between the level of disturbance of the geomagnetic background (Kp-index) and indicators of the functional activity of the cardiovascular system (T-wave symmetry coefficient), when registering an ECG signal in the phase space of coordinates. This paper considers a case in which the data obtained from the study of the values o f the symmetry coefficient of the T wave of an anonymous patient appear, as well as a series of data reflecting fluctuations in the daily index of geomagnetic disturbance recorded daily for 24 days of the study. The result of the work carried out is a working and sufficiently original data processing algorithm that makes it possible to distinguish between people who are sensitive to geomagnetic background disturbances and those who are insensitive to this factor. In the case described as an example in this paper, a significant relationship was found between the presence of geomagnetic disturbance and deviations of the indicators of the activity of the cardiovascular system from normal values, of a functional nature, as evidenced by the significance level p<0.05 obtained for the χ2 criterion, and the exact criterion Fisher, whose value was 0.04977.

Geomagnetically Induced Current Modeling in New Zealand: Extreme Storm Analysis Using Multiple Disturbance Scenarios and Industry Provided Hazard Magnitudes

AbstractGeomagnetically induced currents (GICs) are induced in electrical power transmission networks during geomagnetic disturbances. Understanding the magnitude and duration of the GIC expected during worst‐case extreme storm scenarios is vital to estimate potential damages and disruptions to power networks. In this study we utilize the magnetic field waveforms measured during three large geomagnetic storms and scale them to expected worst case extreme storm magnitudes. Multiple methods are used to simulate the varying magnitude of the magnetic field across the different latitudes of New Zealand. Modeled GIC is produced for nine extreme storm scenarios, each covering 1–1.5 days in duration. Our industry partners, Transpower New Zealand Ltd provided GIC magnitude and duration levels which represent a risk to their transformers. Using these thresholds various extreme storm scenarios predict between 44 and 115 New Zealand transformers (13%–35%) are at risk of damaging levels of GIC. The transformers at risk are largely independent of the extreme storm time‐variations, but depend more on the latitude variation scenario. We show that these at‐risk transformers are not localized to any specific region of New Zealand but extend across all regions and include most of the major population centers. A peak mean absolute GIC over a 60‐min window of 920–2,210 A and an instantaneous 1‐min time resolution maximum GIC of 1,590–4,920 A occurs for a worst‐case extreme storm scenario. We believe this is one of the first studies to combine a reasonable worst‐case extreme geomagnetic storm with validated GIC modeling and industry‐provided GIC risk thresholds.

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.

Polar Geomagnetic Disturbances and Auroral Substorms in the Magnetic Storm of April 20, 2020

Polar Geomagnetic Disturbances and Auroral Substorms in the Magnetic Storm of April 20, 2020

A Proper Use of the Adjacent Land‐Based Observatory Magnetic Field Data to Account for the Geomagnetic Disturbances During Offshore Directional Drilling

AbstractDirectional drilling in the oil fields relies particularly on the “on‐fly” measurements of the natural magnetic field (measurements while drilling; MWD); the MWD are eventually used to construct the well path. These measurements are the superposition of the signals from the internal, core and crustal, and external, ionospheric and magnetospheric sources and the noise from magnetic elements in the borehole assembly. The internal signals are mostly constant in time and accounted for through the Earth's internal field models. The signals of external origin give rise to diurnal and irregular spatio‐temporal magnetic field variations observable in the MWD. One of the common ways to mitigate the effects of these variations in the MWD is to correct readings for the data from an adjacent land‐based magnetic observatory/site. This method assumes that the land‐based signals are similar to those at the seabed drilling site. In this paper, we show that the sea level and seabed horizontal magnetic fields differ significantly, reaching up to 30% of sea level values in many oceanic regions. We made this inference from the global forward modeling of the magnetic field using realistic models of conducting Earth and time‐varying sources. To perform such modeling, we elaborated a numerical approach to efficiently calculate the spatio‐temporal evolution of the magnetic field. Finally, we propose and validate a formalism allowing researchers to obtain trustworthy seabed signals using measurements at the adjacent land‐based site and exploiting the modeling results, thus without needing additional measurements at the seabed site.

Global Electromagnetic Disturbances Caused by the Eruption of the Tonga Volcano on 15 January 2022

AbstractThe study is devoted to the analysis of geomagnetic field disturbances and the response of the Schumann resonance (SR) during the eruption of the Tonga volcano in 2022. The data on geomagnetic field variations at distances from 800 to 15,000 km from the volcano according to the INTERMAGNET network and parameters of SR signals recorded at Mikhnevo Observatory in Russia were used. The source of global geomagnetic disturbances are acoustic–gravity waves (AGWs), which caused changes in ionospheric conductivity, values of ionospheric currents, and the geomagnetic field. The propagation velocity of magnetic disturbances 263 ± 5 m/s, corresponding to the AGWs velocity, was determined and an independent estimate of the time of the eruption phase that caused the generation of the atmospheric wave (4:14 ± 10 UT) was obtained. A new method of processing the results of measurements of SR disturbance with a time resolution of 5 min instead of the usual 10–15 min allowed not only to detect but also to study this phenomenon in detail. The peculiarities of signals related to the number and energy of lightning discharges were revealed. Synchronous measurements of SR signals and geomagnetic field variations in a single observatory for the first time allowed to obtain an independent estimate of the eruption time and the electromagnetic disturbance propagation rate.

A Study of the Relationship Between Southward Bz > -10 nT and Storm Time Disturbance Index During Solar Cycle 23

Magnetic reconnection can be used for studying the geoeffective processes in the coupled Sun–Solar wind – Magnetosphere dynamics leading to geomagnetic disturbance. In this study, 1-hour resolution solar wind plasma parameters from OMNIweb were used to investigate the relationship between moderate southward interplanetary magnetic field, IMF-Bz (i.e., Bz > -10 nT) and geomagnetic storm time disturbance, Dst , during the ascending, maximum and descending phases of solar cycle 23. Occurrences of different classes of geomagnetic storms during moderate southward Bz are reported. The occurrence of weak and moderate geomagnetic storms is more predominant during maximum solar activity than intense and super intense storms. It was found that 10.11 % (181) of all the classes of the storm were intense, and 0.17 % (3) were super intense storms. Furthermore, it was found that 4 (2.2 %) out of the 181 intense storms were caused by southward Bz > -10 nT which were associated with the complex structure due to the high-speed solar wind stream and corotating interacting region. In such a complex structure and Bz > -10 nT, we observed that an intense geomagnetic storm rarely occurs and if it does, would be predominant around solar maximum. It was found that long-duration (\Delta t > 6 hrs) of southward Bz (i.e., -10 nT < Bz <= -3.6 nT ) can also lead to an intense geomagnetic storm during the solar maximum and descending phase (moderate solar activity) of a solar cycle. The complex structure of intense geomagnetic storms associated with the Bz > -10 nT is rare and possesses a special configuration of magnetic field and solar wind parameters structures which are CIR manifestations.

Mitigating the Impacts of Uncertain Geomagnetic Disturbances on Electric Grids: A Distributionally Robust Optimization Approach

Severe geomagnetic disturbances (GMDs) increase the magnitude of the electric field on the Earth’s surface (E-field) and drive geomagnetically-induced currents (GICs) along the transmission lines in electric grids. These additional currents can pose severe risks, such as current distortions, transformer saturation and increased reactive power losses, each of which can lead to system unreliability. Several mitigation actions (e.g., changing grid topology) exist that can reduce the harmful GIC effects on the grids. Making such decisions can be challenging, however, because the magnitude and direction of the E-field are uncertain and non-stationary. In this paper, we model uncertain E-fields using the distributionally robust optimization (DRO) approach that determines optimal transmission grid operations such that the worst-case expectation of the system cost is minimized. We also capture the effect of GICs on the nonlinear AC power flow equations. For solution approaches, we develop an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">accelerated</i> column-and-constraint generation (CCG) algorithm by exploiting a special structure of the support set of uncertain parameters representing the E-field. Extensive numerical experiments based on “epri-21” and “uiuc-150” systems, designed for GMD studies, demonstrate (i) the computational performance of the accelerated CCG algorithm, (ii) the superior performance of distributionally robust grid operations that satisfy nonlinear, nonconvex AC power flow equations and GIC constraints, in comparison with standard stochastic programming-based methods during the out-of-sample testing.

Modeling geomagnetic induction in submarine cables

Submarine cables have become a vital component of modern infrastructure, but past submarine cable natural hazard studies have mostly focused on potential cable damage from landslides and tsunamis. A handful of studies examine the possibility of space weather effects in submarine cables. The main purpose of this study is to develop a computational model, using Python, of geomagnetic induction on submarine cables. The model is used to estimate the induced voltage in the submarine cables in response to geomagnetic disturbances. It also utilizes newly acquired knowledge from magnetotelluric studies and associated investigations of geomagnetically induced currents in power systems. We describe the Python-based software, its working principle, inputs/outputs based on synthetic geomagnetic field data, and compare its operational capabilities against analytical solutions. We present the results for different model inputs, and find: 1) the seawater layer acts as a shield in the induction process: the greater the ocean depth, the smaller the seafloor geoelectric field; and 2) the model is sensitive to the Ocean-Earth layered conductivity structure.

Analysis of Ionospheric Perturbations Possibly Related to Yangbi Ms6.4 and Maduo Ms7.4 Earthquakes on 21 May 2021 in China Using GPS TEC and GIM TEC Data

On 21 May 2021 (UT), Yangbi Ms6.4 and Maduo Ms7.4 earthquakes occurred in mainland China. This paper analyzed the ionospheric perturbations possibly related to the earthquake, based on global positioning system (GPS) total electron content (TEC) and global ionosphere map (GIM) TEC data. We identified GPS TEC anomalies by the sliding quartile, based on statistical analysis. After eliminating the days with high solar activity levels and strong geomagnetic disturbances, the time series analysis of GPS TEC data showed that there were significant TEC anomalies from 5 to 10 May. TEC anomalies were mainly positive anomalies. We obtained the spatial and temporal distributions of TEC anomalies using natural neighbor interpolation (NNI). The results showed that the TEC anomalies were distributed in the seismogenic zone and surrounded the epicenters of the Maduo and Yangbi earthquakes, indicating that they may be related to the earthquakes. From the GIM TEC difference map, we found the TEC enhancement in the seismogenic zone and its magnetic conjugate area of the Maduo and Yangbi earthquakes at 10:00–12:00 (UT) on the 5 and 6 May. We discussed our results according to the lithosphere-atmosphere-ionosphere coupling mechanism. Finally, based our results, we suggested that the Yangbi and Maduo earthquakes may affect the ionosphere through seismogenic electric field and thermal anomalies generated during the process of lithosphere-atmosphere-ionosphere coupling.

Space weather phenomena on heart rate: a study in the Greek region

Many scientific investigations have focused on how space weather phenomena, taking place in the vicinity of the Earth, may influence different aspects of life on Earth and presumably human health itself. From 2005, the National and Kapodistrian University of Athens has established an important position in the field of these investigations by collaborating with various scientists and Institutes, both international and domestic, in different heliobiological projects. In this work, the Cosmic Ray Group of the National and Kapodistrian University of Athens has co-operated with the medical staff from different hospitals and clinics around the country so as to develop large records of medical data (heart rate) which covers a long time period. These data are analyzed in regard to physical activity, either on a daily basis or on different levels of geomagnetic disturbances and variations of the cosmic ray intensity using the ANalysis Of Variance (ANOVA) and the multiple linear regression analysis. Results suggest that space weather phenomena may be related to heart rate variability, i.e., heart rate is statistically significantly effected either by variations of cosmic rays intensity or geomagnetic activity.

Ionospheric effects of the 5–6 January 2019 eclipse over the People's Republic of China: results from oblique sounding

Abstract. This paper deals with the variations in the Doppler spectra and in the relative amplitudes of the signals observed at oblique incidence over the People's Republic of China (PRC) during the partial solar eclipse of 5–6 January 2019 and on reference days. The observations were made using the multifrequency multipath radio system for sounding the ionosphere at oblique incidence. The receiver system is located at the Harbin Engineering University, PRC, and 14 HF broadcasting station transmitters are used for taking measurements along the following radio-wave propagation paths: Lintong/Pucheng to Harbin, Hwaseong to Harbin, Chiba/Nagara to Harbin, Hailar/Nanmen to Harbin, Beijing to Harbin (three paths), Goyang to Harbin, Ulaanbaatar/Khonkhor to Harbin, Yakutsk to Harbin (two paths), Shijiazhuang to Harbin, Hohhot to Harbin, and Yamata to Harbin. The specific feature of this partial solar eclipse was that it occurred during the local morning with a geomagnetic disturbance (Kp ≈ 3−) in the background. The response of the ionosphere to the solar eclipse has been inferred from temporal variations in the Doppler spectra, the Doppler shift, and the signal relative amplitude. The partial solar eclipse was found to be associated with broadening of the Doppler spectrum, up to ± 1.5 Hz, alternating sign Doppler-shift variations, up to ± 0.5 Hz, in the main ray, and quasi-periodic Doppler-shift changes. The relative amplitude of electron density disturbances in the 15 min period of atmospheric gravity wave field and in the 4–5 min period of infrasound wave field is estimated to be 1.6 %–2.4 % and 0.2 %–0.3 %, respectively. The estimates of a maximum decrease in the electron density are in agreement with the observations.

Geomagnetic Disturbances That Cause GICs: Investigating Their Interhemispheric Conjugacy and Control by IMF Orientation

AbstractNearly all studies of impulsive geomagnetic disturbances (GMDs, also known as magnetic perturbation events MPEs) that can produce dangerous geomagnetically induced currents (GICs) have used data from the northern hemisphere. In this study, we investigated GMD occurrences during the first 6 months of 2016 at four magnetically conjugate high latitude station pairs using data from the Greenland West Coast magnetometer chain and from Antarctic stations in the conjugate AAL‐PIP magnetometer chain. Events for statistical analysis and four case studies were selected from Greenland/AAL‐PIP data by detecting the presence of &gt;6 nT/s derivatives of any component of the magnetic field at any of the station pairs. For case studies, these chains were supplemented by data from the BAS‐LPM chain in Antarctica as well as Pangnirtung and South Pole in order to extend longitudinal coverage to the west. Amplitude comparisons between hemispheres showed (a) a seasonal dependence (larger in the winter hemisphere), and (b) a dependence on the sign of the By component of the interplanetary magnetic field (IMF): GMDs were larger in the north (south) when IMF By was &gt;0 (&lt;0). A majority of events occurred nearly simultaneously (to within ±3 min) independent of the sign of By as long as |By| ≤ 2 |Bz|. As has been found in earlier studies, IMF Bz was &lt;0 prior to most events. When IMF data from Geotail, Themis B, and/or Themis C in the near‐Earth solar wind were used to supplement the time‐shifted OMNI IMF data, the consistency of these IMF orientations was improved.

Intergroup Cascade Broad Learning System With Optimized Parameters for Chaotic Time Series Prediction

The prediction of chaotic time series can well describe the physical properties and influencing factors of a sequence of numerical data points in successive order and has played an increasingly crucial role in various scientific and engineering communities. These time series data require the prediction model to have strong dynamic feature representation ability, which often leads to excessive calculation burden. As an emerging and effective learning method, a broad learning system (BLS) can be trained quickly by incremental learning, and the system can be reconstructed without requiring a lengthy retraining process, which has been shown to facilitate superior time-saving performance. However, the historical information of time series data is often ignored, resulting in the lack of dynamic feature representation ability of the original BLS algorithm. In this article, a novel intergroup cascade BLS (ICBLS) method and its variant with optimized parameters, termed MOICBLS, are proposed, which can combine the previous knowledge with current information to determine the output results by constructing a novel intergroup cascade structure for the enhancement nodes. The new algorithms try to retain the time-saving advantage of BLS and greatly enhance the extraction ability of dynamic features of chaotic time series data. In addition, it cannot be ignored that the network structure parameters have an unquestionable impact on the performance of a BLS. In response, two conflicting goals of prediction accuracy and diversity are formulated as multiobjective optimization functions in the training phase to generate the optimized network structure parameters needed by multiple candidate models. The experimental results on two benchmark chaotic time series dataset, the Lorenz system and Rossler system, and a geomagnetic disturbance storm time chaotic time series dataset demonstrate that our proposed algorithms are effective for prediction of chaotic time series, and the prediction accuracy is better than some existing approaches.