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Geomagnetic activity control of irregularities occurrences over the crests and trough of the African EIA
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  • Paul, Obiakara Amaechi,
  • Elijah, Oyedola Oyeyemi,
  • Andrew, Oke-Ovie Akala,
  • Christine Amory-Mazaudier
Paul, Obiakara Amaechi
Chrisland University

Corresponding Author:paoloobiaks@yahoo.fr

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Elijah, Oyedola Oyeyemi
University of Lagos
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Andrew, Oke-Ovie Akala
University of Lagos
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Christine Amory-Mazaudier
University Pierre and Marie Curie
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This paper examined the behavior of ionospheric irregularities over the African Equatorial Ionization Anomaly (EIA) during intense geomagnetic storms which occurred from 2012 to 2015. Total electron content (TEC) data was used to derive the rate of change of TEC index (ROTI). This was employed to monitor irregularities over the trough and crests of the EIA. Variations of the horizontal component of the Earth’s magnetic field (H) were examined. The H component was additionally used to compute ionospheric electric current disturbance (Diono). Prompt penetration electric field (PPEF) inferred from variations of Diono was compared with PPEF obtained from the Prompt Penetration Equatorial Electric Field Model (PPEFM). The PPEFM predicted accurately all PPEFs thus, was found to be valid over the African EIA. The local time of occurrence of interplanetary magnetic field (IMF ) dictated the behavior of irregularities. Eastward PPEF triggered short duration irregularities on 23 April 2012, 17 March 2013 and 20 February 2014 while westward disturbance dynamo electric field (DDEF) reduced them thereafter. During the storms recovery including the 15 July 2012 and 17 March 2015 events, irregularities were suppressed by westward DDEF. However, during the storms of 14 November 2012 and 29 June 2013 no irregularities were observed. Irregularities were always inhibited over the trough. The inhibition lasted longer during the super storm of March 2015. Over the crests, there were differences in their behavior on 16-17 July 2012, 15 November 2012 and 19 March 2013. These were however, not linked to storm-time electric field.
Jul 2020Published in Earth and Space Science volume 7 issue 7. 10.1029/2020EA001183