Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa

The magnetic data obtained from a chain of ten magnetotelluric stations installed in the African sector during the international equatorial electrojet year (IEEY) was used to establish the 1993 quiet day current system (Sq) for West Africa and to determine the Earth’s upper mantle electrical co...

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Autores principales:	Obiekezie, T., Okeke, F.
Formato:	article
Lenguaje:	EN
Publicado:	D.Ghitu Institute of Electronic Engineering and Nanotechnologies 2010
Materias:	Physics QC1-999 Electronics TK7800-8360
Acceso en línea:	https://doaj.org/article/c5fc6974e60f44c585d1d352c9d5d559
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spelling	oai:doaj.org-article:c5fc6974e60f44c585d1d352c9d5d5592021-11-21T12:04:00ZUpper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa2537-63651810-648Xhttps://doaj.org/article/c5fc6974e60f44c585d1d352c9d5d5592010-06-01T00:00:00Zhttps://mjps.nanotech.md/archive/2010/article/4231https://doaj.org/toc/1810-648Xhttps://doaj.org/toc/2537-6365The magnetic data obtained from a chain of ten magnetotelluric stations installed in the African sector during the international equatorial electrojet year (IEEY) was used to establish the 1993 quiet day current system (Sq) for West Africa and to determine the Earth’s upper mantle electrical conductivity in the region. A spherical harmonic analysis (SHA) was applied in the separation of the internal and external field/current contribution to the Sq variations, while a special transfer function was used to compute the conductivity – depth values from the paired external and internal coefficient of the SHA. The variation in the currents is seen to be a dawn to dusk phenomenon with the variation in the external currents different from that of the internal currents both in amplitude and in phase. The seasonal variation in the external current maximizes during the March equinox and minimizes in the December solstice. The conductivity had a downward increase with a high conductivity region spotted between 100 km and 205 km, which is seen to correspond to the seismic low velocity region. The conductivity at the upper mantle is seen to be 1.05 times higher than that obtained both in the Asian (Himalayan) and Australian regions. Obiekezie, T.Okeke, F.D.Ghitu Institute of Electronic Engineering and NanotechnologiesarticlePhysicsQC1-999ElectronicsTK7800-8360ENMoldavian Journal of the Physical Sciences, Vol 9, Iss 2, Pp 199-204 (2010)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999 Electronics TK7800-8360
spellingShingle	Physics QC1-999 Electronics TK7800-8360 Obiekezie, T. Okeke, F. Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa
description	The magnetic data obtained from a chain of ten magnetotelluric stations installed in the African sector during the international equatorial electrojet year (IEEY) was used to establish the 1993 quiet day current system (Sq) for West Africa and to determine the Earth’s upper mantle electrical conductivity in the region. A spherical harmonic analysis (SHA) was applied in the separation of the internal and external field/current contribution to the Sq variations, while a special transfer function was used to compute the conductivity – depth values from the paired external and internal coefficient of the SHA. The variation in the currents is seen to be a dawn to dusk phenomenon with the variation in the external currents different from that of the internal currents both in amplitude and in phase. The seasonal variation in the external current maximizes during the March equinox and minimizes in the December solstice. The conductivity had a downward increase with a high conductivity region spotted between 100 km and 205 km, which is seen to correspond to the seismic low velocity region. The conductivity at the upper mantle is seen to be 1.05 times higher than that obtained both in the Asian (Himalayan) and Australian regions.
format	article
author	Obiekezie, T. Okeke, F.
author_facet	Obiekezie, T. Okeke, F.
author_sort	Obiekezie, T.
title	Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa
title_short	Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa
title_full	Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa
title_fullStr	Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa
title_full_unstemmed	Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa
title_sort	upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of west africa
publisher	D.Ghitu Institute of Electronic Engineering and Nanotechnologies
publishDate	2010
url	https://doaj.org/article/c5fc6974e60f44c585d1d352c9d5d559
work_keys_str_mv	AT obiekeziet uppermantleconductivitydeterminedfromthesolarquietdayionosphericcurrentsinthedipequatoriallatitudesofwestafrica AT okekef uppermantleconductivitydeterminedfromthesolarquietdayionosphericcurrentsinthedipequatoriallatitudesofwestafrica
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Upper mantle conductivity determined from the solar quiet day ionospheric currents in the dip equatorial latitudes of West Africa

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