Atmospheric and Climate Sciences, 2016, 6, 319-328 Published Online April 2016 in SciRes. http://www.scirp.org/journal/acs http://dx.doi.org/10.4236/acs.2016.62027 How to cite this paper: Ahmed, W.A., Agbaje, G.I., Ayeiola, S.Y., Balogun, B.O., Echoda, N.J.A., Onimago, Y.A. and Olunuga, T. (2016) Determination of Total Electron Content at Equatorial Region—Thailand Using Radio Occultation Technique. At- mospheric and Climate Sciences, 6, 319-328. http://dx.doi.org/10.4236/acs.2016.62027 Determination of Total Electron Content at Equatorial Region—Thailand Using Radio Occultation Technique * Wasiu Akande Ahmed 1,2 , Ganiyu Ishola Agbaje 2 , Sikiru Yommy Ayeiola 3 , Bola O. Balogun 2 , Ngbede Joshua Ada Echoda 2 , Yakubu Abdullahi Onimago 2 , Taiwo Olunuga 2 1 School of Instrumentation Science and Opto-Electronics Engineering, Beihang University of Aeronautics and Astronautics, Beijing, China 2 African Regional Centre for Space Science and Technology Education-English, OAU Campus, Ile-Ife, Nigeria 3 School of Electronics and Information Engineering, Beihang University, Beijing, China Received 24 February 2016; accepted 26 April 2016; published 29 April 2016 Copyright © 2016 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract This paper investigates the total electron content (TEC) which is a major challenge to space and related industries, most especially in an equatorial region like Thailand within the geographical latitude 07˚35'N - 20˚17'N. This research was achieved using radio occultation data from COSMIC mission. The monthly, seasonal and annual TEC and electron density variation monitoring con- ducted during increasing solar activity from 2010 to 2013 due to changes and instability of ionos- pheric parameters. It was observed that electron density and TEC was predominant in summer season. Summer has the highest electron density and TEC values all through and the annual mean values keep on increasing within the period under consideration. In conclusion, ionospheric fluc- tuations and perturbations were observed to be at pick between the months of March and May. The results of the study demonstrated that ionospheric irregularities were steadily on the in- crease, confirming 24th solar cycle prediction by NASA and depended on many factors among the major ones which are located on the latitude, season and solar activity. Keywords TEC, Ionosphere, GPS, Low Earth Orbit, Radio Occultation, Equatorial Zone * Ionospheric communication delay measurement due to total electron content (TEC).