The anomalous wet 2020 southeast Brazil austral summer: characterization and possible mechanisms

Abstract

This paper analyzed the anomalous rainy austral summer of 2020 over the southeastern region of Brazil (SEB), investigating its possible mechanisms. The SEB experienced dry summers in the years before 2020; however, the austral summer of 2020 in this region was the wettest since 1991. A wave train starting from the Indian Ocean to the Pacific Ocean, plus a wave train from the tropical north (U-shape), and another from the western equatorial Pacific (PSA-like) contributed to an anomalous anticyclonic circulation at high levels southward South America. This merged wave train continued its path with an anomalous cyclonic circulation over the southern region of Brazil and the state of Sao Paulo, and anticyclonic near SEB, southern Brazil and Argentina coastal. The South Atlantic SST and the wave trains generated an anticyclonic anomalous circulation over the southern region of Brazil and cyclonic northward, in opposition to the 2020 configuration.