Tropical Pacific Influence on Summertime South African High-Frequency Temperature Variability and Heat Waves

Abstract

The dominant mode of interannual variability in summertime high-frequency tropospheric temperature fluctuations over Southern Africa is found to be associated with tropical Pacific sea surface temperature variability, in such a manner that El Niño is typically accompanied by enhanced high-frequency variability. This relationship is established via El Niño's teleconnection that contributes to shifting the midlatitude jetstream and associated baroclinic zone equatorward, into the vicinity of Southern Africa, which enhances the baroclinic conversion of energy from the seasonal-mean flow to high-frequency eddies. The enhanced temperature variance, combined with the overall warmer summertime-mean temperatures induced by El Niño, results in more frequent warm extremes over Southern Africa.