Climatic aspects and vertical structure circulation associated with the severe drought in Northeast Brazil (2012–2016)

Abstract

This study provides an updated dynamical analysis of the observed climate conditions during the longest, most severe and continuous drought (2012–2016) ever recorded in Northeast Brazil (NEB). This investigation was carried out based on temperature, precipitation, sea surface temperature, outgoing long-wave radiation, and ERA-Interim reanalysis data from 1981 to 2016. This was done by first looking for the area of the NEB where the drought was most severe, and then calculating the main rainy season anomalies and atmospheric parameters from 2012 to 2016 in relation to the climatological conditions (1981–2010). Results show this drought event was influenced mainly by two distinct oceanic conditions that induced anomalous atmospheric circulation patterns. The observed negative precipitation anomalies were firstly related to the northward displacement of the Intertropical Convergence Zone (ITCZ), followed by an anomalous upward motion over the Western Amazon, as well as the anomalous precipitation deficit along the South Atlantic Convergence Zone, that was slightly displaced southward of the climatological position. From 2015 to 2016 the subsidence over NEB Brazil was linked to the descending branch of the Walker circulation, as well as to the strong anomalous flow induced by convection in the ITCZ over Africa and Gulf of Mexico.