RAINFALL AND TEMPERATURE ANOMALIES FROM 1991-2010
ABSTRACT
This study examines the rainfall and temperature anomalies at Sokoto for the period 1991-2010. The data on monthly rainfall and temperature of Sokoto were collected from the Nigerian Metrological Agency (NIMET) Sultan Abubakar III International Airport. Sokoto respectively. Simple linear regression and coefficient (r) simple correlation analysis was used to fit the trend in annual rainfall amount, mean monthly temperature (minimum and maximum) for the period of the study. Data analysis was carried out by statistical package of the social science (SPSS) and also Microsoft excel program were used to input and drawing of chart or graph was also used to determine the trend in annual rainfall amount, mean monthly temperature (min and max for the period of the study. The student’s ’test was also used to test the significance of the correlation. Detailed analysis of the result showed that there was a downward trend in annual rainfall amount; no significant trend in mean minimum temperature over the period of the study. However, an upward trend was observed in the period 1991-2010. The study recommends that the shelter belt should be planted in cushion the effect of the changing climate in the area. The study suggests that the study on the impact of climatic variability on human welfare should be conducted.
CHAPTER ONE
1.1 BACKGROUND OF THE STUDY
Rainfall 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).
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