ABSTRACT:The sensitivity of the atmospheric circulation and rainfall over southern Africa to various regional sea surface temperature (SST) patterns observed during Benguela Niño events is investigated using an atmospheric general circulation model (AGCM). The model used is the United Kingdom Meteorological Office (UKMO) HadAM3 and experiments using idealizations of observed regional SST anomalies during various Benguela Niño events are performed. It is found that SST forcing in the tropical southeast Atlantic induces a regional baroclinic response and that a Benguela Niño is capable of forcing anomalous rainfall along the Angolan and northern Namibian coastal regions on its own, via changes in low level moisture convergence, uplift and evaporation over the SST forcing.An experiment with the tropical southeast Atlantic SST anomaly shifted slightly further north produced a larger circulation and rainfall response in the model. Additional experiments with various SST anomalies in the southwest Indian Ocean combined with those in the southeast Atlantic were performed. These experiments are motivated by the fact that South Indian Ocean SST anomalies of varying signs often occur at the same time as Benguela Niño events. The results of these experiments suggest that, depending on its sign, magnitude and location, SST forcing from the southwest Indian Ocean may augment or oppose the southern African rainfall anomalies occurring during a Benguela Niño event to varying degrees.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.