Influence of Nonmigrating Tides and Geomagnetic Field Geometry on the Diurnal and Longitudinal Variations of the Equatorial Electrojet

2020 ◽  
Vol 125 (6) ◽  
Author(s):  
Hui Wang ◽  
Zhichao Zheng ◽  
Kedeng Zhang ◽  
Wenbin Wang
Keyword(s):  
Geomagnetic Field ◽  
Equatorial Electrojet ◽  
Longitudinal Variations ◽  
Field Geometry ◽  
Nonmigrating Tides

THE STUDY OF LONGITUDINAL AND LATITUDINAL VARIATION OF EQUATORIAL ELECTROJET SIGNATURE AT STATIONS WITHIN THE 96°MM AND 210°MM AFRICAN AND ASIAN SECTORS RESPECTIVELY UNDER QUIET CONDITIONS.

2021 ◽  
Vol 5 (2) ◽  
pp. 511-532
Author(s):  
Aniefiok Akpaneno ◽  
Matthew Joshua ◽  
K. R. Ekundayo
Keyword(s):  
Seasonal Variation ◽  
Geomagnetic Field ◽  
Satellite Communication ◽  
Equatorial Electrojet ◽  
Latitudinal Variation ◽  
Magnetic Data ◽  
Horizontal Magnetic Field ◽  
Baseline Values ◽  
The Difference ◽  
Current Systems

Solar quiet current (S_q) and Equatorial Electrojet (EEJ) are two current systems which are produced by electric current in the ionosphere.  The enhancement of the horizontal magnetic field is the EEJ. This research is needed for monitoring equatorial geomagnetic current which causes atmospheric instabilities and affects high frequency and satellite communication. This study presents the longitudinal and latitudinal variation of equatorial electrojet signature at stations within the 96°mm and 210°mm African and Asian sectors respectively during quiet condition. Data from eleven observatories were used for this study. The objectives was  to determine the longitudinal and latitudinal geomagnetic field variations during solar quiet conditions, Investigate monthly variation and diurnal transient seasonal variation; Measure the strength of the EEJ at stations within the same longitudinal sectors and find out the factors responsible for the longitudinal and latitudinal variation of EEJ. Horizontal (H) component of geomagnetic field for the year 2008 from Magnetic Data Acquisition System (MAGDAS) network were used for the study. The International Quiet Days (IQDs) were used to identify quiet days. Daily baseline values for each of the geomagnetic element H  were obtained.  The monthly average of the diurnal variation was found. The seasonal variation of dH was found. Results showed that: The longitudinal and latitudinal variation in the dH differs in magnitude from one station to another within the same longitude due to the difference in the influence of the EEJ on them.

scholarly journals A Comparison of Equatorial Electrojet in Peru and East Brazil

2013 ◽  
Vol 7 (1) ◽  
pp. 29-36 ◽  
Author(s):  
R.G. Rastogi ◽  
H. Chandra ◽  
Rahul Shah ◽  
N.B. Trivedi ◽  
S.L. Fontes
Keyword(s):  
South America ◽  
Geomagnetic Field ◽  
Daily Variation ◽  
Equatorial Electrojet ◽  
Horizontal Component ◽  
Low Latitude ◽  
Vertical Field ◽  
The Mean ◽  
Western Side ◽  
The Magnetic Field

The paper describes the characteristics of the equatorial electrojet at Huancayo (HUA, 12.1oS, 75.3oW, inclination 1.5oN, declination 1.0oE) in western side of South America, where the geomagnetic field is aligned almost along the geographic meridian, and at Itinga (ITI, 4.3oS, 47.oW, inclination 1.4oN, declination 19.3oW) in eastern part of South America, where the geomagnetic field is aligned about 19o west of the geographic meridian; although the mean intensity of the magnetic field in the two regions are almost of the same order. Further comparisons are made of the current at Itinga and at Tatuoca (TTB, 1.2oS, 48.5oW, inclination 7.8o N, declination 18.7oW), a low latitude station in the same longitude sector. The daily range of horizontal component of the geomagnetic field, H, is shown to be almost 16% higher at HUA compared to that at ITI. The daily variation of the eastward field, Y, showed a strong minimum of -40 nT around 13-14 hr LT at ITI whereas very low values were observed at HUA with a positive peak of about 4 nT around 11- 12 hr LT. The vertical field, Z, showed abnormally large negative values of -70 nT at TTB around 13 hr LT. The day-today fluctuations of midday and midnight values of X field were positively correlated between HUA and ITI with a high correlation coefficient of 0.78 and 0.88 respectively. Values of Y field were also significantly positively correlated between HUA and ITI for midnight hours (0.72), while no correlation was observed for the midday hours. The midnight values of X field at HUA, ITI and TTB showed significant (0.90 or greater) correlation with Dst index. Correlation values of about 0.7 were observed between Dst and midday values of X at ITI and TTB and to a lesser degree (0.4) at HUA.

INVESTIGATING THE VARIATIONS OF HORIZONTAL (H) AND VERTICAL (Z) COMPONENTS OF THE GEOMAGNETIC FIELD AT SOME EQUATORIAL ELECTROJET STATIONS

2021 ◽  
Vol 5 (1) ◽  
pp. 539-557
Author(s):  
Aniefiok Akpaneno ◽  
O. N. Abdulahi
Keyword(s):  
Seasonal Variations ◽  
High Frequency ◽  
Geomagnetic Field ◽  
Satellite Communication ◽  
Geomagnetic Latitude ◽  
Equatorial Electrojet ◽  
Geomagnetic Equator ◽  
Monthly Average ◽  
June Solstice ◽  
Baseline Values

This research is monitoring equatorial geomagnetic current which causes atmospheric instabilities and affects high frequency and satellite communication. It presents the variations of Horizontal (H) and vertical (Z) component of the geomagnetic field at some Equatorial Electrojet (EEJ) Stations during quiet days. Data from five (5) observatories along the magnetic equator were used for the study. Daily baseline values for each of the geomagnetic element 𝐻 and Z were obtained. The monthly average of the diurnal variation and the seasonal variations were found. Results showed that the variations of the geomagnetic element of both H and Z differ in magnitudes from one stations to another along the geomagnetic Equator due to the differences of their geomagnetic latitude. The Amplitude curves for Z) are seen to be conspicuously opposite to that of H), and there is absence of CEJ in Z- Component but present in H- Components. The  values during the pre-sunrise hours are low compare to daytime hours. Minimum variations of dH was observed during June solstice and maximum variations was observed during Equinox season. This study shows that daily variations of (H) and (Z) occur in all the stations. The enhancement in H is as a result of EEJ current.

scholarly journals An intense SFE and SSC event in geomagnetic <i>H</i>, <i>Y</i> and <i>Z</i> fields at the Indian chain of observatories

1997 ◽  
Vol 15 (10) ◽  
pp. 1301-1308 ◽  
Author(s):  
R. G. Rastogi ◽  
D. R. K. Rao ◽  
S. Alex ◽  
B. M. Pathan ◽  
T. S. Sastry
Keyword(s):  
Solar Flare ◽  
Geomagnetic Storm ◽  
Geomagnetic Field ◽  
Current System ◽  
Equatorial Electrojet ◽  
Start Time ◽  
Low Latitude ◽  
Ionospheric Current ◽  
Ionospheric Current System ◽  
Solar Flare Effects

Abstract. Changes in the three components of geomagnetic field are reported at the chain of ten geomagnetic observatories in India during an intense solar crochet that occurred at 1311 h 75° EMT on 15 June 1991 and the subsequent sudden commencement (SSC) of geomagnetic storm at 1518 h on 17 June 1991. The solar flare effects (SFE) registered on the magnetograms appear to be an augmentation of the ionospheric current system existing at the start time of the flare. An equatorial enhancement in ΔH due to SFE is observed to be similar in nature to the latitudinal variation of SQ (H) at low latitude. ΔY registered the largest effect at 3.6° dip latitude at the fringe region of the electrojet. ΔZ had positive amplitudes at the equatorial stations and negative at stations north of Hyderabad. The SSC amplitude in the H component is fairly constant with latitude, whereas the Z component again showed larger positive excursions at stations within the electrojet belt. These results are discussed in terms of possible currents of internal and external origin. The changes in the Y field strongly support the idea that meridional current at an equatorial electrojet station flows in the ionospheric dynamo, E.

scholarly journals The influence of nonmigrating tides on the longitudinal variation of the equatorial electrojet

2008 ◽  
Vol 113 (A8) ◽  
pp. n/a-n/a ◽  
Author(s):  
H. Lühr ◽  
M. Rother ◽  
K. Häusler ◽  
P. Alken ◽  
S. Maus
Keyword(s):  
Equatorial Electrojet ◽  
Longitudinal Variation ◽  
Nonmigrating Tides

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 Day-to-day correlation of equatorial electrojet at two stations separated by 2000 km

2007 ◽  
Vol 25 (4) ◽  
pp. 875-880 ◽  
Author(s):  
R. G. Rastogi ◽  
H. Chandra ◽  
D. Chakrabarty ◽  
K. Kitamura ◽  
K. Yumoto
Keyword(s):  
Spectral Analysis ◽  
Geomagnetic Field ◽  
Ring Current ◽  
Equatorial Electrojet ◽  
Time Effects ◽  
Mean Values ◽  
Remarkable Similarity ◽  
Dst Index ◽  
Daily Range ◽  
Dominant Period

Abstract. Day-to-day fluctuations of the daily range of the geomagnetic field H at the equatorial electrojet stations Ancon (ANC, 77.0° W) and Sao Luis (SLZ, 44.2° W) are described for the period January–June 1993. The H field started increasing between midnight and sunrise, reaching a peak shortly before noon. The daily range of H was maximum during March and April and minimum during June. Regardless of the month, the range in H was significantly larger at ANC than at SLZ. The 27-day running mean of the range of H varied from 80 nT to 125 nT at SLZ and from 105 nT to 180 nT at ANC. The day-to-day values of the range of H showed very faithful variations at the two stations. The deviations of the daily range of H from its 27-day running mean values showed good correlation between the two stations. Some large storm-time effects were seen at both stations. The correlation was still significant, when data were corrected for Dst index values. It is suggested that the range in H at the two electrojet stations, separated by more than 2000 km, are affected by some common sources other than the ring current, which need to be identified. Spectral analysis of the range of H shows remarkable similarity at the two stations, with a dominant period of 15 days at both stations.

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