Moisture sources to the 2010–2012 anomalous wet season in northern South America

Abstract

During 2010–2012, northern South America experienced one of the strongest wet seasons during the recent decades, with socio-economic implications of wide proportions. This period was characterized by two stronger-than-average La Nina events, one occurred in 2010–2011 and another less intense event in 2011–2012. This study focused on identifying the main moisture sources, besides the eastern Pacific, for the anomalous wet season occurred in this region during 2010–2012, and their association with the La Nina events observed in the equatorial Pacific. The results discussed here suggest that the main moisture sources to this anomalous wet season were the Pacific Ocean (via the westerly flow of the Choco jet) and the Caribbean Sea (via the weakening of the Caribbean low-level jet and the development of southward anomalies toward northern South America). Such changes appear to be associated not only to El Nino-Southern Oscillation (ENSO)-driven sea surface temperature anomalies in the eastern Pacific, Caribbean Sea, and north Atlantic, but also to ENSO-independent variability in the Atlantic Ocean. The latter is related to an enhanced Atlantic Meridional Mode.