Regionalization of Botswana rainfall during the 1980s using principal component analysis



A regionalization of decadal rainfall for Botswana is presented. Situated on the southern African plateau, this subtropical country offers little physiographical variation on which geographical subdivision can be based. Following similar studies a varimax rotated principal component analysis was selected as the regionalization method. Nine years of rainfall (1980–1988) for 49 stations were analysed. Component loading fields, and hence regions, are interpreted in terms of the varying influence of synoptic configurations on the various parts of the country. The first component, explaining about half of the total variance, is found to be associated with the dominant position of the surface trough in summer, with which most rainfall in Botswana is associated. The other components are interpreted as variations of this primary synoptic pattern.