TRANSEQUATORIAL FIELD-ALIGNED CURRENTS AT LOW LATITUDES AND THEIR POSSIBLE CONNECTION WITH THE EQUATORIAL ELECTROJET

2018 ◽  
Vol 11 (3) ◽  
Author(s):  
N. Fukushima
Keyword(s):  
Equatorial Electrojet ◽  
Low Latitudes

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scholarly journals ANALISIS PENGARUH PENETRASI MEDAN LISTRIK LINTANG TINGGI KE LINTANG RENDAH TERHADAP IONOSFER SAAT BADAI GEOMAGNET (ANALYSIS OF THE ELECTRIC FIELD PENETRATION EFFECT FROM HIGH TO LOW LATITUDES ON THE IONOSPHERE DURING GEOMAGNETIC STORM)

2018 ◽  
Vol 14 (2) ◽  
pp. 97
Author(s):  
Anwar Santoso ◽  
Dadang Nurmali ◽  
Mira Juangsih ◽  
Iyus Edi Rusnadi ◽  
Sri Ekawati ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Current ◽  
High Latitude ◽  
Delay Time ◽  
Geomagnetic Storms ◽  
Equatorial Electrojet ◽  
Minimum Point ◽  
Low Latitude ◽  
Dst Index ◽  
Low Latitudes

The influence of geomagnetic storms on the ionosphere in the equatorial and low latitudes can be either rising or falling value of the value foF2 with the different response delay time. The difference in response is one of them allegedly influenced by the modification of Equatorial Electrojet (EEJ) generated by the penetration of high latitude electric field towards the low latitude electric field and the equator. Therefore, this paper analyzes the influence of the high latitude penetration of electric current to the low latitude electric current towards the ionosphere response to Indonesia's current geomagnetic storms using the data foF2 BPAA Sumedang (SMD; 6,910 S; 106,830E geographic coordinates or 16,550 S; 179,950 E magnetic coordinates) and data from the Biak geomagnetic field station (BIK; 1,080 S; 136,050 E geographic coordinates or  9,730 S; 207,390 E magnetic coordinates) in 2000-2001. The result showed that the injection of the electric field of the high latitudes to lower latitudes causing foF2 BPAA Sumedang to be disturbed. Onset of the foF2 disturbance in BPAA Sumedang started coincide with EEJ(HBIK-HDRW) and reached its minimum point with a time delay between 0 to 4 hours before and after Dst index reached the minimum point. For a delay time of 0 to 4 hours after the Dst index reached the minimum point, the results were in accordance with the research results from the prior research. However, for the time difference of between 0 to 4 hours before the Dst index reached the minimum point, the results differ from their results. AbstrakPengaruh badai geomagnet terhadap ionosfer di ekuator dan lintang rendah berupa naiknya nilai foF2 atau turunnya nilai foF2 dengan waktu tunda respon berbeda-beda. Perbedaan respon tersebut salah satunya diduga dipengaruhi oleh modifikasi Equatorial electrojet (EEJ) yang dihasilkan oleh penetrasi medan listrik lintang tinggi sampai daerah lintang rendah dan ekuator. Oleh karena itu, dalam makalah ini dilakukan analisis pengaruh penetrasi arus listrik lintang tinggi ke lintang rendah terhadap ionosfer saat badai geomagnet menggunakan data foF2 dari Balai Pengamatan Antariksa dan Atmosfer (BPAA) Sumedang (SMD; 6,910 LS; 106,830 BT koordinat geografis atau 16,550 LS; 179,950 BT koordinat magnet) dan data medan geomagnet dari stasiun Biak (BIK; 1,080 LS; 136,050 BT koordinat geografis atau 9,730 LS; 207,390 BT koordinat magnet) tahun 2000-2001. Hasilnya diperoleh bahwa penetrasi medan listrik dari lintang tinggi ke lintang lebih rendah Indonesia menyebabkan foF2 BPAA Sumedang terganggu. Onset gangguan foF2 BPAA Sumedang mulai terjadi bertepatan dengan EEJ(HBIK-HDRW) mencapai titik minimumnya dengan jeda waktu antara 0 sampai 4 jam sebelum dan sesudah indeks Dst mencapai minimum. Untuk beda waktu 0 sampai 4 jam sesudah indeks Dst mencapai minimum, hasilnya bersesuaian dengan hasil penelitian peneliti sebelumnya. Namun, untuk beda waktu 0 sampai 4 jam sebelum indeks Dst mencapai minimum, hasilnya merupakan temuan berbeda dari hasil mereka.

scholarly journals Observations of equatorial ionization anomaly over Africa and Middle East during a year of deep minimum

2017 ◽  
Vol 35 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Olawale Bolaji ◽  
Oluwafisayo Owolabi ◽  
Elijah Falayi ◽  
Emmanuel Jimoh ◽  
Afolabi Kotoye ◽  
...  
Keyword(s):  
Middle East ◽  
Continuity Equation ◽  
Equatorial Electrojet ◽  
Data Acquisition System ◽  
Magnetic Data ◽  
Electron Content ◽  
Deep Minimum ◽  
Total Electron ◽  
Equatorial Ionization Anomaly ◽  
Low Latitudes

Abstract. In this work, we investigated the veracity of an ion continuity equation in controlling equatorial ionization anomaly (EIA) morphology using total electron content (TEC) of 22 GPS receivers and three ground-based magnetometers (Magnetic Data Acquisition System, MAGDAS) over Africa and the Middle East (Africa–Middle East) during the quietest periods. Apart from further confirmation of the roles of equatorial electrojet (EEJ) and integrated equatorial electrojet (IEEJ) in determining hemispheric extent of EIA crest over higher latitudes, we found some additional roles played by thermospheric meridional neutral wind. Interestingly, the simultaneous observations of EIA crests in both hemispheres of Africa–Middle East showed different morphology compared to that reported over Asia. We also observed interesting latitudinal twin EIA crests domiciled at the low latitudes of the Northern Hemisphere. Our results further showed that weak EEJ strength associated with counter electrojet (CEJ) during sunrise hours could also trigger twin EIA crests over higher latitudes.

scholarly journals <i>Letter to the Editor:</i> Geomagnetic storm effects at low latitudes

1999 ◽  
Vol 17 (3) ◽  
pp. 438-441 ◽  
Author(s):  
R. G. Rastogi
Keyword(s):  
Electric Fields ◽  
Ring Current ◽  
Daily Variation ◽  
Equatorial Electrojet ◽  
Storm Effects ◽  
Electrical Conductivities ◽  
Low Latitudes ◽  
E Region ◽  
Storms And Substorms ◽  
Electric Fields And Currents

Abstract. The geomagnetic horizontal (H) field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes could be the effect of a westward electric field due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator.Key words. Ionosphere (electric fields and currents) · Magnetospheric physics (electric fields; storms and substorms)

scholarly journals Statistical study of the DP2 enhancement at the dayside dip-equator compared to low latitudes

2011 ◽  
Vol 29 (12) ◽  
pp. 2225-2233 ◽  
Author(s):  
N. M. Mene ◽  
A. T. Kobea ◽  
O. K. Obrou ◽  
K. Z. Zaka ◽  
K. Boka ◽  
...  
Keyword(s):  
Statistical Study ◽  
Equatorial Electrojet ◽  
Magnetic Effect ◽  
Longitudinal Variation ◽  
Enhancement Ratio ◽  
Polar Cap ◽  
Maximum Value ◽  
Low Latitudes ◽  
Magnetometer Data ◽  
Dip Equator

Abstract. It has been largely investigated and established that the DP2 events are enhanced at dip-equator compared to low latitudes. Studies by several authors showed various enhancement ratio values of DP2 amplitude at the dayside dip-equator relative to those at low latitudes. In order to quantify this enhancement ratio, we carried out a statistical study on this phenomenon using the ground magnetometer data at locations ranging from polar cap to dip-equator over the African, Asian and American sector. Our result gave an enhancement ratio which shows a diurnal variation with a maximum value around 12:00 LT and is correlated with the regular variation of the geomagnetic H-component. The longitudinal variation of the enhancement ratio of the DP2 exhibits high values over the American sector compared to Asian sector and African sector which have lowest values. This longitudinal dependence is similar to that of the equatorial electrojet magnetic effect.

scholarly journals Induction effects of geomagnetic disturbances in the geo-electric field variations at low latitudes

2017 ◽  
Vol 35 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Vafi Doumbia ◽  
Kouadio Boka ◽  
Nguessan Kouassi ◽  
Oswald Didier Franck Grodji ◽  
Christine Amory-Mazaudier ◽  
...  
Keyword(s):  
Solar Flare ◽  
Electric Field ◽  
West Africa ◽  
Geomagnetic Storm ◽  
Geomagnetic Field ◽  
Equatorial Electrojet ◽  
Geomagnetic Disturbances ◽  
The North ◽  
Low Latitudes ◽  
Dip Equator

Abstract. In this study we examined the influences of geomagnetic activity on the Earth surface electric field variations at low latitudes. During the International Equatorial Electrojet Year (IEEY) various experiments were performed along 5° W in West Africa from 1992 to 1995. Among other instruments, 10 stations equipped with magnetometers and telluric electric field lines operated along a meridian chain across the geomagnetic dip equator from November 1992 to December 1994. In the present work, the induced effects of space-weather-related geomagnetic disturbances in the equatorial electrojet (EEJ) influence area in West Africa were examined. For that purpose, variations in the north–south (Ex) and east–west (Ey) components of telluric electric field were analyzed, along with that of the three components (H,  D and Z) of the geomagnetic field during the geomagnetic storm of 17 February 1993 and the solar flare observed on 4 April 1993. The most important induction effects during these events are associated with brisk impulses like storm sudden commencement (ssc) and solar flare effect (sfe) in the geomagnetic field variations. For the moderate geomagnetic storm that occurred on 17 February 1993, with a minimum Dst index of −110 nT, the geo-electric field responses to the impulse around 11:00 LT at LAM are Ex =  520 mV km−1 and Ey =  400 mV km−1. The geo-electric field responses to the sfe that occurred around 14:30 LT on 4 April 1993 are clearly observed at different stations as well. At LAM the crest-to-crest amplitude of the geo-electric field components associated with the sfe are Ex =  550 mV km−1 and Ey =  340 mV km−1. Note that the sfe impact on the geo-electric field variations decreases with the increasing distance of the stations from the subsolar point, which is located at about 5.13° N on 4 April. This trend does not reflect the sfe increasing amplitude near the dip equator due the high Cowling conductivity in the EEJ belt.

scholarly journals Analysis of Magnetic Field Variations Produced by Equatorial Electro-Jets

2017 ◽  
Vol 13 (S335) ◽  
pp. 125-127
Author(s):  
Ericson López ◽  
Franklin Aldás ◽  
Akimasa Yoshikawa
Keyword(s):  
Magnetic Field ◽  
Data Analysis ◽  
Narrow Band ◽  
Equatorial Electrojet ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Electron Current ◽  
Low Latitudes ◽  
Magnetic Field Variations

AbstractThe Equatorial Electrojet (EEJ) is a narrow band of electrons flowing from east to west at daytime at low latitudes. The electron current produces a magnetic field variation that can be measured at different latitudes. In this work, we have used the data analysis in order to quantify the solar and lunar contributions to those variations and study the morphology of the EEJ current.

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