Longitudinal Responses of the Equatorial/Low‐Latitude Ionosphere Over the Oceanic Regions to Geomagnetic Storms of May and September 2017

A. O. Akala (1) , E. O. Oyeyemi (1) , P. O. Amaechi (1, 2) , S. M. Radicella (3) , B. Nava (3) , Christine Amory-Mazaudier (4, 3)

1 University of Lagos
2 Chrisland University
3 ICTP - Abdus Salam International Centre for Theoretical Physics [Trieste]
4 LPP - Laboratoire de Physique des Plasmas

This study presents the longitudinal dependence of responses of the equatorial/low latitude ionosphere over the oceanic regions to geomagnetic storms of 28th May and 8th September, 2017. We investigated the interplanetary origins of the storms. Total Electron Content (TEC) data were obtained from Global Navigation Satellite System stations, located around the oceanic areas in the equatorial/low latitude regions. The Rate of change of TEC Index (ROTI) was used as a proxy for ionospheric irregularities over the study locations. Further, variations of the horizontal component of the Earth's magnetic fields, obtained from ground-based magnetometers were studied. We used ionospheric disturbance currents, polar cap and auroral electrojet indices to monitor the storm-time electric fields. The May, 2017 storm was driven by sheath and magnetic cloud fields, while the September, 2017 storm was driven by sheath fields. We observed a comparative dominance of TEC intensities over the Oceans than over the landlocked areas. Empirically, our results validated a theoretical suggestion of the existence of a dynamic ocean-ionosphere coupling made by Godin et al. [2015]. Prompt Penetration Electric Fields (PPEF) was observed to be a key factor that controls TEC responses to storms. PPEFs caused TEC enhancements, mainly over the Pacific Ocean longitudes during the May, 2017 storm and enhanced TEC over the Atlantic Ocean and the Pacific Oceans longitudes during the September, 2017 storm. These PPEFs triggered irregularities over the Pacific

Mots clés: Geomagnetic storms; ionospheric irregularities; total electron content; storm-time electric fields

Domaines: Géophysique [physics.geo-ph]

A. O. Akala, E. O. Oyeyemi, P. O. Amaechi, S. M. Radicella, B. Nava, et al.. Longitudinal Responses of the Equatorial/Low‐Latitude Ionosphere Over the Oceanic Regions to Geomagnetic Storms of May and September 2017. Journal of Geophysical Research Space Physics, 2020, 125 (8), ⟨10.1029/2020JA027963⟩. ⟨hal-02926010⟩