Longitudinal Responses of the Equatorial/Low‐Latitude Ionosphere Over the Oceanic Regions to Geomagnetic Storms of May and September 2017. Issue 8 (31st July 2020)

• Record Type: Journal Article
• Authors: Akala, A. O.; Oyeyemi, E. O.; Amaechi, P. O.; Radicella, S. M.; Nava, B.; Amory‐Mazaudier, C.
• Is Part Of: Journal of geophysical research. Volume 125:Issue 8(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-31
• Subjects: geomagnetic storms -- ionospheric irregularities -- total electron content -- storm time electric fields; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2020JA027963
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: This study presents the longitudinal dependence of responses of the equatorial/low‐latitude ionosphere over the oceanic regions to geomagnetic storms of 28 May and 8 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, http://10.0.4.162/s40623-015-0212-4 ). 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 Ocean longitudes, particularly during the main phase of May 2017 storm. Irregularities were generally inhibited by the September 2017 storm. Key Points: May and September 2017 geomagnetic storms were driven by sheath fields in conjunction with magnetic cloud and sheath fields May 2017 storm triggered irregularities over the Pacific Ocean; September storm inhibited irregularities; PPEF controls TEC responses A coupling between the ocean and the ionosphere exists; TEC intensities were dominant over the Oceans than over the landlocked areas