Wavelet analysis of climate change in West African countries using surface temperature

Abstract

Surface temperature variations in West Africa stations (Cameroon, Cote d’Ivore, Ghana, Niger, Nigeria, Senegal and Togo) were investigated using datasets obtained from the archives of World Bank Data Group between 1901 and 2015 (115 years). Wavelet power spectrum (WPS) based approach was engaged to evaluate the surface temperature time series in a sequence of time scales. It
was observed that there is more concentration of power between 1950 and 1970 year bands, which demonstrates that the time series has a strong annual signal with a confidence level of 95%. Statistical approach was also used to determine the minimum, maximum, mean, standard deviation, kurtosis and skewness. We noticed that Senegal (SEN) has the highest temperature and a Cameroon
(CMR) exhibit low temperature from the selected stations in West Africa. The monthly spatial and temporal changes in temperature displayed increasing trends which were found in the annual, monthly maximum and minimum temperature during the period 1901 to 2015. The spatial variability illustrates that the lower latitude corresponds to lower temperature variability while the upper
latitudes corresponds to a higher temperature. This variability is associated with the upward and downward movement of the intertropical convergence zone (ITCZ) as controlled by air mass flow. The temperature patterns might also be influenced by the changes in cloudiness consequential from variations in atmospheric circulation, and variations in aerosol content in the atmosphere.