RAINFALL AND TEMPERATURE ANOMALIES FROM 1991-2010

Thesis Overview

1.1         BACKGROUND OF THE STUDYRainfall in Nigeria is highly seasonal in character with well-marked wet and dry seasons, these are characteristics of the monsoon type of climate. As rainfall decreases from the coast to the interior both in amount and in duration, along the coast to the mean annual total rainfall from 4295mm at bonny in the east to only 5775mm at Lagos in the west. Northwards the annual rainfall decrease in land to less than 700mm in the lake Chad basin (Maiduguri) (Oguntoyimbo, 1978). The latitudinal falling off in rainfall is interrupted by the effects of the relief in the interior. The Niger-Benue trough, lying generally on the leeward side of the eastern upland receives less than average rainfall fort its latitude while north of the trough, the Jos plateau, whose southern wind ward slopes receives season ranges from eight to ten months in the south to less than a months in the extreme north-west (Oguntoyimbo, 1978). Seasonal variation in the rainfall is only attributed to fluctuations of the boundary between the two major air masses which influence the climate of West Africa. These are originated from the Atlantic ocean, and the dry dust laden tropical continental (ITD) air mass, which originated from the Sahara desert. The boundary between these two air masses, the inter-tropical discontinuity ITD (is significant because it separates two distinct term of weather on either side, but unlike the temperate latitudes, it does not give rise to any particular activities associated with the boundary itself. During the northern winter, when the surface location of the ITD lies at about latitude 70N across Nigeria, there is only shallow depth on MT air covering the coastal areas, giving rise to occasional showers in the Niger delta between December and February. Most of the interior is then under the desiccating influence of the dust earing CT air mass (Oguntoyimbo, 1978) The distribution of the total amount of rainfall in the tropics has been examined on different time and spatial scales. Almost every where in the tropics, the annual totals differ widely from year to tear, and in addition, it varies strongly with places as well as the rainfall characteristic, such as its seasonal and diurnal distribution intensity, duration and frequency of raiding. These variations are due to certain factors at both macro and micro levels. Once macro scale, variations of rainfall are caused by a number of factors, usually in combinations. The most important of these is of course, the inter-tropical convergence zone (ITCZ) and the length of its stay over a certain area (Ayoade, 1978).1.2         AIM AND OBJECTIVE OF THE STUDYThe basic aim of this research work is to examine the anomalies in rainfall and temperature at Sokoto between (1991 - 2010)1.3         OBJECTIVES OF THIS RESEARCH WORK ARE:·         To determine the rainfall anomaly pattern at Sokoto.·         To determine the temperature anomaly pattern.·         Trend in annual rainfall and temperature (maximum and minimum)