scholarly journals ANALISIS RESPON MEDAN GEOMAGNET ANTARA STASIUN DI EKUATOR MAGNET DAN STASIUN BIAK SAAT BADAI GEOMAGNET PADA MERIDIAN MAGNET 210⁰ MM

2016 ◽  
Vol 13 (2) ◽  
pp. 63
Author(s):  
Anwar Santoso
Keyword(s):  
Response Time ◽  
Geomagnetic Storm ◽  
Geomagnetic Field ◽  
Field Data ◽  
Geomagnetic Storms ◽  
Geomagnetic Disturbance ◽  
Magnetic Equator ◽  
High Latitudes ◽  
Geomagnetic Equator ◽  
Occurrence Probability

Geomagnetic storm is a geomagnetic disturbance that occurs globally. Until now believed that the greatest impact of geomagnetic storms occurred in the high latitudes and decreases with decreasing latitude to the equator. However, based on the data component of the geomagnetic field H obtained CPMN other phenomena, that is H minimum of Onagawa station (31,15o LU; 212,63o BT magnetic coordinates) is smaller than the H minimum at Biak station (9,73o latitude; 207,39o BT magnetic coordinates) during geomagnetic storms on July 15, 2000. This reality is different from what was believed to be on top. To ensure this, then done the analysis of the geomagnetic field H component response based on the latitude using the geomagnetic field data from Biak station and stations around 210o MM for the whole event a strong geomagnetic storms (Dst <-100 nT) during 1995-2001. Results of the analysis showed that the response time of geomagnetic field geomagnetic storm in Biak is greater than at the magnetic equator (YAP) with an difference average of H is 59,27 nT. EEJ and CEJ pattern in the EEJ region (10o S to 10o N magnetic coordinate) shown could effected to the response of geomagnetic geomagnetic. The most important to note that if the geomagnetic response in Indonesia higher than in the geomagnetic equator (YAP) then the occurrence probability of GIC in Indonesia is higher.  AbstrakBadai geomagnet merupakan gangguan geomagnet yang terjadi secara global. Sampai saat ini dipercaya bahwa dampak terbesar badai geomagnet terjadi di lintang tinggi dan semakin menurun dengan menurunnya lintang sampai di ekuator. Namun, berdasarkan olah data komponen H medan geomagnet dari CPMN diperoleh fenomena lain yaitu H minimum dari stasiun Onagawa (31,15⁰ LU; 212,63⁰ BT koordinat magnet) lebih kecil dari H minimum Balai Penjejakan dan Kendali Wahana Antariksa (BPKWA) Biak (9,73⁰ LS; 207,39⁰ BT koordinat magnet) saat badai geomagnet 15 Juli 2000. Kenyataan ini berbeda dari apa yang telah dipercayai di atas. Untuk memastikan hal ini maka dilakukan analisis respon komponen H medan geomagnet berdasarkan lintang menggunakan data komponen H medan geomagnet dari BPKWA Biak dan stasiun di sekitar 210⁰ MM untuk seluruh kejadian badai geomagnet kuat (Dst < -100 nT) selama 1995-2001. Hasil analisis diperoleh bahwa respon medan geomagnet saat badai geomagnet di Biak lebih besar dari pada di ekuator magnet (YAP) dengan rata-rata selisih ∆H-nya 59,27 nT. EEJ dan CEJ di daerah EEJ (10⁰ LU sampai 10⁰ LS magnet) terbukti mempengaruhi respon geomagnet. Hal terpenting yang perlu diperhatikan dari hasil ini adalah bahwa jika respon geomagnet di Indonesia lebih tinggi dibandingkan di daerah ekuator geomagnet (YAP) maka potensi kemunculan GIC juga lebih besar terjadi di Indonesia. 

scholarly journals Variability of Geomagnetic Field with Interplanetary Magnetic Field at Low, Mid and High Latitudes

2018 ◽  
Vol 10 (2) ◽  
pp. 133-144
Author(s):  
S. Bhardwaj ◽  
P. A. Khan ◽  
R. Atulkar ◽  
P. K. Purohit
Keyword(s):  
Magnetic Field ◽  
Coronal Mass Ejection ◽  
Interplanetary Magnetic Field ◽  
Geomagnetic Storm ◽  
High Latitude ◽  
Geomagnetic Field ◽  
The State ◽  
High Latitudes ◽  
Storm Events ◽  
Mass Ejection

 The fluctuations in the Interplanetary Magnetic Field significantly affect the state of geomagnetic field particularly during the Coronal Mass Ejection (CME) events. In the present investigation we have studied the influence of Interplanetary Magnetic Field changes on the geomagnetic field components at high, low and mid latitudes. To carry out this investigation we have selected three stations viz. Alibag (18.6°N, 72.7°E), Beijing MT (40.3°N, 116.2°E) and Casey (66.2°S, 110.5°E) one each in the low, mid and high latitude regions. Then we selected geomagnetic storm events of three types namely weak (-50≤Dst≤-20), moderate (100≤Dst≤-50) and intense (Dst≤-100nT). In each storm category 10 events were considered. From our study we conclude that geomagnetic field components are significantly affected by the changes in the IMF at all the three latitudinal regions during all the storm events. At the same time we also found that the magnitude of change in geomagnetic field components is highest at the high latitudes during all types of storm events while at low and mid latitude stations the magnitude of effect is approximately the same.

Studying the Ionospheric Responses Induced by a Geomagnetic Storm in September 2017 with Multiple Observations in America

2020 ◽  
Author(s):  
Yang Liu ◽  
Zheng Li ◽  
Jinling Wang
Keyword(s):  
Electron Density ◽  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Ionospheric Irregularities ◽  
Electron Content ◽  
High Latitudes ◽  
Total Electron ◽  
Multiple Observations ◽  
The Usa ◽  
Plasma Depletions

&lt;p&gt;A series of studies have suggested that a geomagnetic storm can accelerate the formation of plasma depletions and the generation of ionospheric irregularities. Using observation data from the Continuously Operating Reference Stations (CORS) network in the USA, the responses of the ionospheric total electron content (TEC) to the geomagnetic storm on September 8, 2017 are studied in detail. A mid-latitude trough was discovered from 01:00 UT to 06:00 UT in the USA with a length exceeding 5000 km. The probable causes are the combination of a classic negative storm response with increments in the neutral composition and the expansion of the auroral oval, pushing the mid-latitude trough equatorward. &amp;#160;Super-scale plasma depletion was observed by SWARM data accompanied by the expansion of mid-latitude trough. Both PPEF from high latitudes and pole-ward neutral wind are responsible for the large-scale ionospheric irregularities. Medium-scale travelling ionospheric disturbances (MSTID) with wavelengths of 600&amp;#8211;700 km were generated accompanied by a drop and perturbation in the electron density. The intensity of the MSTID fluctuations reached over 2.5 TECU, which were discovered by filtering the differential TEC. The evolution of plasma depletions were associated with the MSTID propagating from high latitudes to low latitudes. SWARM spaceborne observations also showed a drop in the electron density from 10&lt;sup&gt;5&lt;/sup&gt;&amp;#160;to 10&lt;sup&gt;3&lt;/sup&gt;&amp;#160;compared to the background values at 28&amp;#176; N, 96&amp;#176; W, and 25&amp;#176; N, 95&amp;#176; W. This research investigates super-scale plasma depletions generated by geomagnetic storms using both CORS GNSS and spaceborne observations. The proposed work is valuable for better understanding the evolution of ionospheric depletions during geomagnetic storms.&lt;/p&gt;

A Fuzzy Logic Approach to Evaluate Transformer Fleet Risk From Geomagnetic Storms

2016 ◽  
Author(s):  
Sujit Purushothaman
Keyword(s):  
Fuzzy Logic ◽  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Geomagnetic Latitude ◽  
Geomagnetic Disturbance ◽  
Specific Factor ◽  
Storm Event ◽  
Geoelectric Field ◽  
Fuzzy Logic Approach ◽  
Specific Factors

This paper presents a simple approach to evaluate risk to transformer units from geomagnetic storms. A simple fuzzy logic based approach was used to develop the model which is capable of categorizing transformers in a fleet into three risk categories, i.e., high, medium and low. This model may be used as a first screening step to evaluate a fleet of transformers without conducting time consuming simulations and studies. Critical factors that affect geomagnetically induced current (GIC) flow are used as input parameters to the model. These factors include location-specific, equipment-specific and geomagnetic storm event-specific factors. Location-specific factors include geomagnetic latitude of the location, earth conductivity structure at location and distance of location from coast. Equipment-specific factors include transformer rating and age. The storm event-specific factor of geoelectric field strength was used which is an indication of the return period of the geomagnetic disturbance event. The paper describes the implementation of this model to evaluate fleet risk for a 1 in 100 year event and the Carrington event (largest recorded geomagnetic storm in history). The fuzzy logic membership functions for the inputs are described in detail and the performance of the fuzzy logic model is evaluated.

scholarly journals The Influence of Geomagnetic Storms on Calculating Magnetotelluric Impedance

2021 ◽  
Author(s):  
Hao Chen ◽  
Hideki Mizunaga ◽  
Toshiaki Tanaka
Keyword(s):  
Geomagnetic Storm ◽  
Field Data ◽  
Time Series Data ◽  
Geomagnetic Storms ◽  
Signal To Noise Ratio ◽  
Series Data ◽  
Electromagnetic Signal ◽  
Artificial Noise ◽  
Noise Sources ◽  
Usable Information

Abstract Magnetotelluric (MT) field data contain natural electromagnetic signals and artificial noise sources (instrumental, anthropogenic, etc.). Not all available time-series data contain usable information about the electrical conductivity distribution at depth, particularly when the signal-to-noise ratio (SNR) is low. Geomagnetic storms represent temporary disturbances of the Earth's magnetosphere caused by solar wind-shock wave interacts with Earth's magnetic field. The variation of the electromagnetic signal increases dramatically in the presence of a strong geomagnetic storm. Using the data observed during a strong geomagnetic storm may overcome the locale noise and bring a reliable MT impedance at contaminated sites. Three case studies are presented to show the positive effect of geomagnetic storms on MT field data. A more reliable and interpretable impedance calculated from a survey line contaminated by strong noise is obtained using the data observed during a strong geomagnetic storm.

scholarly journals The influence of geomagnetic storms on the quality of magnetotelluric impedance

2021 ◽  
Author(s):  
Hao Chen ◽  
Hideki Mizunaga ◽  
Toshiaki Tanaka
Keyword(s):  
Geomagnetic Storm ◽  
Field Data ◽  
Geomagnetic Storms ◽  
Amplitude Ratio ◽  
Signal To Noise Ratio ◽  
Series Data ◽  
Electromagnetic Signal ◽  
Artificial Noise ◽  
Signal To Noise ◽  
Noise Ratio

Abstract Magnetotelluric field data contain natural electromagnetic signals and artificial noise sources (instrumental, anthropogenic, etc.). Not all available time-series data contain usable information of the electrical conductivity distribution at depth with a low signal-to-noise ratio. The variation of the natural electromagnetic signal increases dramatically in a strong geomagnetic storm, and the signal-to-noise ratio increases. A more reliable impedance may be obtained using the storm data in a noisy environment. Three field data observed at mid-latitude were used to investigate the effect of geomagnetic storms on MT impedance quality. We mainly combined the coherence between the electric and magnetic fields and the result of MT impedance to evaluate the MT impedance quality; we also used the polarization direction, linear coherence and amplitude ratio between the local and remote magnetic field to evaluate the data quality in the noisy environments. The case studies showed that the utilization of the data observed during the geomagnetic storm could overcome the local noise and bring a reliable impedance.

ANALYSES OF GEOMAGNETIC DATA SETS FROM OBSERVATORIES AND CORRELATION BETWEEN THEM

2020 ◽  
Author(s):  
Laurențiu Asimopolos ◽  
◽  
Natalia-Silvia Asimopoli ◽  
drian-Aristide Asimopolos
Keyword(s):  
Wavelet Analysis ◽  
Geomagnetic Storm ◽  
Geomagnetic Field ◽  
Graphical Representation ◽  
Geomagnetic Storms ◽  
Correlation Coefficients ◽  
Finite Energy ◽  
Solar Cycles ◽  
Time Intervals ◽  
Geomagnetic Data

The purpose of this study was to analyze the associated spectrum of geomagnetic field, frequencies intensity and the time of occurrence. We calculated the variation of the correlation coefficients, with mobile windows of various sizes, for the recorded magnetic components at different latitudes and latitudes. We included in our study the observatories: Surlari (USA), Honolulu (HON), Scott Base (SBA), Kakioka (KAK), Tihany (THY), Uppsala (UPS), Wingst (WNG) and Yellowknife (YKC). We used the data of these observatories from INTERMAGNET for the bigest geomagnetic storm from the last two Solar Cycles. We have used for this purpose a series of filtering algorithms, spectral analysis and wavelet with different mother functions at different levels. In the paper, we show the Fourier and wavelet analysis of geomagnetic data recorded at different observatories regarding geomagnetic storms. Fourier analysis highlight predominant frequencies of magnetic field components. Wavelet analysis provides information about the frequency ranges of magnetic fields, which contain long time intervals for medium frequency information and short time intervals for highlight frequencies, details of the analyzed signals. Also, the wavelet analysis allows us to decompose geomagnetic signals in different waves. The analyzes presented are significant for the studied of the geomagnetic storm. The data for the next days after the storm showed a mitigation of the perturbations and a transition to a quiet day of the geomagnetic field. In both, the Fourier Transformation and the Wavelet Transformation, transformation evaluation involves the calculation of a scalar product between the analyzed signal and a set of signals that form a particular base in the vector space of the finite energy signals. Fourier representation use and orthogonal vectors base, whereas in the case of wavelet there is the possibility to use also bases consisting of independent linear non-orthogonal vectors. Unlike the Fourier transform, which depends only on a single parameter, wavelet transform type depends on two parameters, a and b. As a result, the graphical representation of the spectrum is different, wavelet analysis bringing more information about geomagnetic pattern of each observatory with that own specific conditions

scholarly journals Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

1996 ◽  
Vol 14 (6) ◽  
pp. 608-618 ◽  
Author(s):  
T. Iyemori ◽  
D. R. K. Rao
Keyword(s):  
Ring Current ◽  
Geomagnetic Storms ◽  
Sharp Decrease ◽  
Geomagnetic Disturbance ◽  
Substorm Onset ◽  
Significant Development ◽  
H Index ◽  
Magnetospheric Tail ◽  
Storms And Substorms ◽  
Substorm Onsets

Abstract. In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem.

scholarly journals The geomagnetic field at 1982 from DE-2 and other magnetic field data.

1988 ◽  
Vol 40 (9) ◽  
pp. 1103-1127 ◽  
Author(s):  
R. A. LANGEL ◽  
J. R. RIDGWAY ◽  
M. SUGIURA ◽  
K. MAEZAWA
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Field Data ◽  
Magnetic Field Data

scholarly journals Geomagnetic anomaly associated with Fukushima earthquake on February 13th, 2021

2021 ◽  
Vol 331 ◽  
pp. 07012
Author(s):  
Cipta Ramadhani ◽  
Bulkis Kanata ◽  
Abdullah Zainuddin ◽  
Rosmaliati ◽  
Teti Zubaidah
Keyword(s):  
Data Processing ◽  
Geomagnetic Field ◽  
Field Data ◽  
Low Frequency ◽  
Earthquake Precursors ◽  
Polarization Ratio ◽  
Magnetic Polarization ◽  
Central Frequency ◽  
Electromagnetic Data ◽  
Geomagnetic Anomaly

In this study, we performed research on electromagnetic anomalies related to earthquakes as early signs (precursors) that occurred in Fukushima, Japan on February 13th, 2021. The research focused on the utilization of geomagnetic field data which was derived from the Kakioka (KAK), Kanoya (KNY), and Memambetsu (MMB) observatories, particularly in the ultra-low frequency (ULF) to detect earthquake precursors. The method of electromagnetic data processing was conducted by applying a polarization ratio. In addition, we improved the methodology by splitting the ULF data (which ranged from 0.01-0.1 Hz) into 9 central frequencies and picking up the highest value from each central frequency to get the polarization ratio. The anomaly of magnetic polarization was identified 2-3 weeks before the mainshock in a narrowband frequency in the range of 0.04-0.05 Hz.

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