EXTREME VALUE ANALYSIS OF TEMPERATURE AND RAINFALL: CASE STUDY OF SOME SELECTED REGIONS IN GHANA

ABSTRACT 

Rainfall and temperature are important climatic factors for crop production and affects humans’ basic needs such as health, shelter, food and water in Ghana. However extreme rainfall causes flooding which can lead to loss of lives, properties among others. Extreme temperature also causes drought, hot and cold spells among others which have adverse implications on human beings and agriculture. It is therefore important to know about occurrences of such extreme events and their chances of occurring. Extreme value theory gives us a statistical approach for the occurrences and the magnitude of these extreme cases or rare event that are beyond the scope of available data. In this thesis, we used “extreme value theory” to model the tail distributions of temperature and rainfall in Ghana. Daily data on rainfall and temperature was obtained and it spanned the period January 1960 to December 2012. “Extreme value theory” was used to estimate the extreme occurrence to be expected once every 5, 10, 20, 50 and 100 years respectively. It was observed that the extreme occurrences of temperature and rainfall can be modelled using Weibull and Frechet family of distributions in Ghana respectively. A maximum temperature of 34.7cC, 34.66oC, and 39.6oC was predicted to occur in Accra, Ashanti and Northern regions respectively once every five years. Furthermore, it was estimated that an amount of 88.38mm, 85.61mm, and 81.98mm will be recorded in Accra, Ashanti, and Northern regions once every 5 years respectively. It was recommended that Government should employ all necessary legislative policies to help manage the issue of Global warming considering the substantial rise in temperature in the years ahead based on our forecasted predictions.