Quest Journals Journal of Research in Environmental and Earth Sciences Volume 5 ~ Issue 2 (2019) pp: 45-49 ISSN(Online) :2348-2532 www.questjournals.org *Corresponding Author: C. G. Njumogu 45 | Page Research Paper Upper Mantle Conductivity determined from the Solar Quiet Day Ionospheric Currents in the Equitorial and Low Latitudes of Africa C. G. Njumogu and T. N. Obiekezie Department of Physics and Industrial Physics, Nnamdi Azikiwe University, Awka, Nigeria. Abstract The mantle electrical conductivity-depth profile of equitorial and low latitudes of Africa have been determined using solar quiet day ionospheric current (Sq). The magnetometer data obtained for 2008 from geomagnetic stations installed across Africa by magnetic data acquisition set (MAGDAS) were employed in this study. Ilorin (ILR) was used to represent the equatorial stations while Hermanus (HER) was used to represent the low latitude stations. Gauss spherical harmonic analysis (SHA) method was used to separate the internal and external field contributions to Sq current system. The result depicted that the conductivity in both the equatorial and low latitudes of Africa had a downward increase with a high conductivity region spotted between 100 km and 200 km. This high conductivity region agreed with the global seismic low velocity region, the asthenosphere. The electrical conductivity depth profiles of the low latitude of Africa have a sharp characteristics rise in electrical conductivity towards 400 to 600km depth. A peak was observed from 448.71km with average value 0.301 sm -1 . This characteristics was not conspicuous in the low latitude of Africa. The conductivity at the upper mantle obtained in the equatorial latitude of Africa is seen to be 2.98 times higher than that obtained both in the low latitude of Africa. Received 25 Mar.2020; Accepted 28 Mar.., 2020 © The author(s) 2020. Published with open access at www.questjournals.org I. INTRODUCTION A fluctuating electric current flowing in the Earth’s atmosphere causes corresponding electric currents to flow in the conducting Earth below the source current. The magnitude, direction, and depth of penetration of the induced currents are determined by the characteristics of the source currents as well as the distribution of electrically conducting materials in the Earth. At the Earth’s surface observatories, magnetometers measure the composite of external (source) and internal (induced) field components from the currents. Separating these currents into their individual parts using Spherical Harmonic Analysis (SHA) or other integral methods, the amplitudes and phase relationships were shown to be useful in determining the conductivity of the deep earth [1]. The depth of penetration of the induced current to the deep earth depends on the period of variation of the source current and the distribution of electrically conducting materials in the region of the earth begin investigated. [2] [3] used selected geomagnetic field records to establish the 1990 quiet-day current system (Sq) for Australia. They also determined the Earth’s deep electrical conductivity using the sq current sy stem. [4] used magnetic data obtained from a chain of ten magnetotelluric stations installed in the African sector during the international equatorial electrojet year (IEEY) 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 The aim of this work is to separate the quiet-day field variations obtained in the mid and high equitorial region of Europe into their external and internal field contributions and then to use the paired external and internal coefficient of the SHA to determine the earth’s upper mantle conductivity for the region. Data Source The average hourly geomagnetic data used in this study were obtained from geomagnetic stations established in parts of the region (Ilorin (8.5 o N, 4.68 o E), Lagos (6.4 o N, 3.27 o E), Addis Ababa (9.04 o N, 38.77 o E) and Hermanus (34.34 o S, 19.24 o E)) by magnetic data acquisition set (MAGDAS), Japan for the year 2008.