Trends and periodicities of rainfall over north Africa

Abstract

Trends and periodicities in the annual rainfall of north Africa are studied using data for 45 stations having record lengths of over 60 year. Increasing or decreasing rainfall tendencies are found over large continuous areas in north Africa. These trends, however, are not significant over all the stations in the areas but only at a few places distributed at random. Wherever a trend is significant, It has persistence or a periodicity of more than 40 year. Quasi- Biennial Oscillation (QBO) is exhibited at several stations in the areas of increasing or decreasing trend. Similarly, the 11-year cycle (solar cycle) is also exhibited in both areas. The QBO and the solar cycle are both present at only six stations.