Predictability of the atmospheric circulation patterns in Africa, south of the equator, using variations of the Southern Annular Mode and ENSO

Abstract

AbstractThe contribution of the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) to the variations of the leading modes of atmospheric circulation in Africa south of the equator, during austral summer (i.e., from December to March), is examined in this study. The rotated principal component analysis is applied to classify the leading modes of atmospheric circulation in the study region. The result showed that relatively, through the control of sea level pressure in the mid-latitudes, the SAM is more related to the variability of the austral summer leading modes of atmospheric circulation in the study region. Overall, during the analysis period, the SAM explained about 20% to 46% variance of the leading atmospheric circulation modes. ENSO rather explains up to about 10% to 20% of the variance. Due to the continuous nature of atmospheric circulation, incorporating the co-variability of the classified circulation patterns adds skill to the predictability of the classified leading modes. Overall, the joint variations of the SAM, ENSO, and other less frequent regional circulation patterns that are related to classified leading modes, explained up to 46% to 80% variance of the leading modes—which is indeed an added value in further considering the natural gradient of the classified circulation patterns.