On equatorial geophysics studies: a review on the IGRGEA results during the last decade

Amory‐Mazaudier, Christine; Kobea, A. T.; Vila, P.; Achy-Seka, A.; Blanc, E.; Boka, K.; Bouvet, J.; Cécile, J.-F.; Cohen, Y.; Curto, J. J.; Dukhan, Michel; Doumouya, V.; Fambitakoye, O.; Farges, Thomas; Goutelard, C.; Guisso, E.; Hanbaba, R.; Houngninou, E.; Kone, E.; Lathuillére, C.; Leroux, Y.; Menvielle, M.; Obrou, E.; Petitdidier, Monique; Ogunade, S. O.; Onwumechili, C. Agodi; Rees, D.; Sambou, E.; Sow, Mouhamed; Vassal, Jacques

doi:10.1016/j.jastp.2004.10.001

Cited by 13 publications

(20 citation statements)

References 44 publications

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“…Since the discovery of the EEJ at Huancayo (Peru) near the dip-equator, several studies have been carried out to explain the generating mechanism of the equatorial electrojet (EEJ) [Baker and Martyn, 1953;Chapman and Bartels, 1940]. Reviews on EEJ and CEJ have been made by different researchers [Richmond, 1973;Kane, 1976;Mayaud, 1977;Forbes, 1981;Reddy, 1981Reddy, , 1989Stening, 1985;Rastogi, 1989;Mazaudier et al, 1993;Doumouya et al, 1998;Mazaudier et al, 2005]. During the past few decades, theoretical and scientific models of the ionospheric dynamo have been developed to explain the mechanism of the EEJ flow and its morphology [Sugiura and Cain, 1966;Sugiura and Poros, 1969;Richmond, 1973;Kane and Trivedi, 1982;Stening, 1985;Reddy, 1989;Chandra et al, 2000;Rabiu et al, 2007;Denardini et al, 2009;Abbas et al, 2012;Rastogi et al, 2013;Guizelli et al, 2013].…”

Section: Introductionmentioning

confidence: 99%

Day‐to‐day variability of equatorial electrojet and its role on the day‐to‐day characteristics of the equatorial ionization anomaly over the Indian and Brazilian sectors

et al. 2015

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The equatorial electrojet (EEJ) is a narrow band of current flowing eastward at the ionospheric E region altitudes along the dayside dip equator. Mutually perpendicular electric and magnetic fields over the equator results in the formation of equatorial ionization anomaly (EIA), which in turn generates large electron density variabilities. Simultaneous study on the characteristics of EEJ and EIA is necessary to understand the role of EEJ on the EIA variabilities. This is helpful for the improved estimation of total electron content (TEC) and range delays required for satellite‐based communication and navigation applications. Present study reports simultaneous variations of EEJ and GPS‐TEC over Indian and Brazilian sectors to understand the role of EEJ on the day‐to‐day characteristics of the EIA. Magnetometer measurements during the low solar activity year 2004 are used to derive the EEJ values over the two different sectors. The characteristics of EIA are studied using two different chains of GPS receivers along the common meridian of 77°E (India) and 45°W (Brazil). The diurnal, seasonal, and day‐to‐day variations of EEJ and TEC are described simultaneously. Variations of EIA during different seasons are presented along with the variations of the EEJ in the two hemispheres. The role of EEJ variations on the characteristic features of the EIA such as the strength and temporal extent of the EIA crest has also been reported. Further, the time delay between the occurrences of the day maximum EEJ and the well‐developed EIA is studied and corresponding results are presented in this paper.

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Section: Introductionmentioning

confidence: 99%

Day‐to‐day variability of equatorial electrojet and its role on the day‐to‐day characteristics of the equatorial ionization anomaly over the Indian and Brazilian sectors

et al. 2015

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“…For 15 years the IGRGEA (International Geophysical Research Group in Europe Africa) is involved in geophysics in Africa Amory-Mazaudier et al, 2005). This group started in 1995 in order to continue the scientific work done from 1991 to 1995 in the frame of the IEEY (International Year of the Equatorial Electrojet).…”

Section: Introductionmentioning

confidence: 99%

Sun-Earth System Interaction studies over Vietnam: an international cooperative project

Amory‐Mazaudier¹,

Cohen²,

Doumbia³

et al. 2006

Ann. Geophys.

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“…Therefore, the higher IHFACs density in the African middle‐latitude around noon may be related to an increase in the potential difference between the African Northern and Southern Hemispheres. This increase in potential difference in Africa compared to that found in the longitude range 300°E to 350°E may be due to the almost horizontal positioning of the African geomagnetic equator (Basu et al, ; de La Beaujardière et al, ), which plays a crucial role in modulating ionospheric perturbations in this region (Amory‐Mazaudier et al, ; Hei et al, ; Kintner et al, ; Yizengaw et al, ).…”

Section: Discussionmentioning

confidence: 98%

Excursions of Interhemispheric Field‐Aligned Currents in Africa

et al. 2018

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The interhemispheric field‐aligned currents (IHFACs) are the most evident currents connecting the solar quiet (Sq) current systems in the Northern and Southern Hemispheres. Understanding these coupling currents has practical importance for space weather forecast of the magnetosphere‐ionosphere interactions and their potential impacts on low‐orbiting spacecraft. In this paper, we have examined digital magnetic records from September 2008 to August 2009 at nine Magnetic Data Acquisition System (MAGDAS) stations in order to uniquely determine the variability of IHFACs in terms of their excursions in the African sector. By excursions, we mean the direction in which the IHFACs are moving as a function of local time or latitude. Different from theoretical prediction, we found prominent positive IHFACs around dusk in February and March equinox. A novel feature of this study is the semidiurnal variation control of the coupling between the Northern and Southern Hemispheres. In addition, we found terdiurnal variation in September with their associated strong diurnal variations from October through December. Quite unexpectedly, in January, a significant latitudinal depletion in the intensities of IHFACs was observed from dawn to dusk, compared to any other months under investigation, accompanied with a marked reduction of the prominent diurnal variations at the magnetic equator (Addis Ababa, AAB). The fact that the excursions of IHFACs in January experience an unusual retardation with respect to their intensities points to a relation with the effects of sudden stratospheric warming.

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On equatorial geophysics studies: a review on the IGRGEA results during the last decade

Cited by 13 publications

References 44 publications

Day‐to‐day variability of equatorial electrojet and its role on the day‐to‐day characteristics of the equatorial ionization anomaly over the Indian and Brazilian sectors

Day‐to‐day variability of equatorial electrojet and its role on the day‐to‐day characteristics of the equatorial ionization anomaly over the Indian and Brazilian sectors

Sun-Earth System Interaction studies over Vietnam: an international cooperative project

Excursions of Interhemispheric Field‐Aligned Currents in Africa

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