Indonesian Journal of Electrical Engineering and Computer Science Vol. 19, No. 1, July 2020, pp. 276~284 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v19.i1.pp276-284  276 Journal homepage: http://ijeecs.iaescore.com Estimation of the refractivity gradient from measured essential climate variables in Iyamho-Auchi, Edo State, South-South Region of Nigeria Kingsley Eghonghon Ukhurebor 1 , Wilson Nwankwo 2 1 Climatic/Environmental/Telecommunication Physics Unit, Department of Physics, Edo University Iyamho, Nigeria 2 Software Engineering/Cyber Physical Lab, Department of Computer Science, Edo University Iyamho, Nigeria Article Info ABSTRACT Article history: Received Nov 2, 2019 Revised Dec 10, 2019 Accepted Jan 16, 2020 Meteorological variables are crucial constituents in the estimation of refractivity disseminations and the uncharacteristic radio wave propagation situations of the troposphere as a result of their impact on radio wave communication relations over the atmosphere. In this study the measurement and assessment of air temperature, relative humidity and atmospheric pressure was carried out for a period of one year; 2018, so as to estimate the refractivity gradient over Iyamho-Auchi, Edo State, Nigeria using a self-implemented inexpensive portable meteorological monitoring device. The measurements of the essential climate variables were done at the administrative building of Edo University Iyamho by placing the meteorological monitoring device on a fixed position. The results show that the monthly estimated refractivity gradient values which would be useful in the prediction of the local radio propagation range from -20.00 N-units/km to -190.00 N-units/km with an average value of -60.67 N-units/km for the period under consideration. The findings also show that the months with limited relative humidity have greater refractivity gradient values compared to the ones with higher relative humidity. It was also observed from the results that the measured essential climate variables were having significant impacts on the estimated refractivity gradient during all the months in 2018, and these impacts were more noticeable in the months with higher relative humidity compared with the months that were having limited relative humidity. Keywords: Atmospheric pressure Radio waves Refractivity Relative humidity Temperature Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Kingsley Eghonghon Ukhurebor, Climatic/Environmental/Telecommunication Unit, Department of Physics, Edo University Iyamho, P.M.B. 04 Auchi, Edo State, Nigeria. Email: ukhurebor.kingsley@edouniversity.edu.ng 1. INTRODUCTION Meteorological variables are very important in the derivation of refractivity disseminations and the local radio wave propagation situations of the troposphere, as a result of their effect on radio wave communication links in the troposphere [1-14]. Refractivity distributions studies play a momentous role in dealing effectively with the complications that arise as a result of the uncharacteristic radio wave propagation and unexpected path loss that disturbs the performance of radio signals from cellular network, navigation and surveillance systems. Most essential climate variables like air temperature, relative humidity and atmospheric pressure need to be adequately accessed so as to have better local radio propagation conditions, which would enhance the quality of services of cellular network service providers, navigation and radar system designers.