《Southern Africa monthly rainfall variablity--Ambrosionamp;Chandleramp;Todd amp;》.pdf

4600 J O U R N A L O F C L I M A T E VOLUME 24 Southern African Monthly Rainfall Variability: An Analysis Based on Generalized Linear Models CHIARA AMBROSINO Department of Geography, University College London, London, United Kingdom RICHARD E. CHANDLER Department of Statistical Science, University College London, London, United Kingdom MARTIN C. TODD Department of Geography, University of Sussex, Brighton, United Kingdom (Manuscript received 7 July 2010, in final form 23 November 2010) ABSTRACT Southern Africa is characterized by a high degree of rainfall variability, affecting agriculture and hydrology, among other sectors. This paper aims to investigate such variability and to identify stable relationships with its potential drivers in the climate system; such relationships may be used as the basis for the statistical down- scaling of climate model outputs, for example. The analysis uses generalized linear models (GLMs). The GLMs are fitted to twentieth-century observational data for the period 1957–2006 to characterize the de- pendence of monthly precipitation occurrences and amounts upon the climate indicators of interest. In contrast with many of the analyses that have previously been used to investigate controls on precipitation in the region, GLMs allow for the investigation of the relationships betw