Rainfall and Temperature Variations in a Dry Tropical Environment of Nigeria

Abstract

This study examines long-term rainfall and temperature variations over a dry tropical environment in Nigeria. An assessment of the variations of these weather variables showcases the extent of climate change limits and corresponding effects on the biotic environment. Rainfall and temperature data were obtained from Nigerian Meteorological Agency for a period of 31 years (1991-2020) for Kano and Katsina States. Descriptive statistics were used to determine the degree of variability of the weather variables across spatial domains. Results showed that there is a sharp contrast in mean annual rainfall amounts of 1154.1 mm and 569.6 mm for Kano and Katsina located in the dry continental and semi-arid climate zones of Nigeria respectively. It is revealed that the month of August had the highest mean monthly rainfall for both areas i.e. 359 mm and 194 mm with little or no trace during the dry season. The sharp difference in rainfall amount across spatial domains of the near similar climate zones shows that the Inter-tropical Discontinuity (ITD) does not completely overwhelm the northern band of Nigeria in August. The least variable monthly rainfall was in August and July with coefficient variations (CV) of 40% and 47% for Kano and Katsina. The months of February and March had the highest CV of 557% and 273% for the respective areas. In the examined areas the wet and dry seasons are from June-September and October-May respectively. The index of rainfall variability and drought intensity for the areas ranged from 0.85-0.95 and 45% indicating moderate variability and drought respectively. Mean annual temperature values are 33.4 °C and 33.8 °C for Kano and Katsina. The study recommends a proper climate observing scheme, most especially for agrarian practices so as to ensure profitable outputs for human sustainability.