DIURNAL ANALYSIS OF DECADAL CHANGES IN SOME CLIMATE VARIABLES OVER SEMI-ARID AND HUMID ZONES IN NIGERIA
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Abstract
Anthropogenic activities such as industrialization in the Humid zone and agricultural practices in the Semi-Arid Zone have been linked to the changes in climate such as desert encroachment, soil degradation and pollution facing these zones in Nigeria. In order to study the extent of these changes, diurnal analysis of decadal changes in meteorological parameters such as air temperature, solar radiation, precipitation and relative humidity were carried out on ten stations covering the Semi-Arid and Humid climatic zones in Nigeria for the period of 1996-2015. In this research, Nigeria was sub-divided into four seasonal groups using the 3-monthly interval scales such as December, January and February as DJF season; March, April and May as MAM season; June, July and August as JJA season; September, October and November as SON season. Surface data of the above climate variables were obtained from European Centre for Medium-Range Weather Forecast’s ERA-Interim database. Analyses showed that the changes in temperature and solar radiation in the Humid zone have positive values at the five selected stations in the zone during the DJF season with Enugu having the highest values of 0.75oC and 12.00 W/m2 respectively. Meanwhile, in the Semi-Arid zone, the changes in temperature and solar radiation were observed to have negative values during the four seasons. Also, changes in relative humidity and precipitation in the Humid Region were observed to have negative values in DJF season. Therefore, air temperature is increasing steadily as the relative humidity is decreasing per decadal cycle in the humid zone while decadal changes show decrease change in air temperature and increasing change in relative humidity in the Semi-Arid zone. It can be concluded that the time of day, seasonal changes and location greatly affect climate conditions in Nigeria and hence, they have contributed to climate change presently experienced in this country.