Harmonic investigation of temperature and sunshine using Fourier series: A case study of the northern and western stations in Nigeria

Abstract

The astronomical factors, geographical location, propensity, and temperature variability over time determined Nigeria's surface temperature and spatial distribution. As such, this investigation focuses on the harmonic temperature and sunshine of a northern and western station in Nigeria. The daily data for temperature and sunshine are collected for Ikeja (Western Nigeria) and Maiduguri (Northern Nigeria) from the Nigerian Meteorological Agency (NiMet) from the year 2010–2020. The data are studied and analyzed using a statistical tool. The harmonic analysis of the collected data is carried out using the Fourier series representation. From the temperature and sunshine of both Ikeja and Maiduguri, the peak periods for Maiduguri occur periodically, with maximums occurring every year at periods of every 3600 degrees depicting the months of December and January as months of high temperatures, while for Ikeja the peak periods occur periodically with maximums occurring every year at periods of 4000, depicting the months December to February as months of high temperatures. Sunshine for Maiduguri is observed to be at peak periods periodically, with maximum occurring every year at periods of every 3600 degrees depicting the months of December and January corresponding with temperature peaks. A peak minimum is observed in the year 2017. It is observed that the peak harmonic for temperature in Ikeja is higher than that of Maiduguri, as opposed to sunshine hours in Maiduguri, whose peak harmonic is higher than that of Ikeja. This could be due to population density or industrialization, but it is evident that Global warming effects are felt more in Ikeja than in Maiduguri.