Do the recent severe droughts in the Amazonia have the same period of length?

TL;DR

This study introduces a new measure for comparing drought periods in Amazonia, revealing distinct spatial and oceanic influences on the 2005 and 2010 droughts, with implications for understanding regional climate variability.

Contribution

It develops a novel drought period length measure and demonstrates its effectiveness in distinguishing spatial responses and oceanic influences on Amazonian droughts.

Findings

2005 drought in South Amazon caused by North Atlantic SST

2010 drought involved phases influenced by El Niño and North Atlantic SST

Different oceanic mechanisms affect drought severity and spatial extent

Abstract

We propose a new measure based on drought period length to assess the temporal difference between the recent two severe droughts of 2005 and 2010 in the Amazonia. The sensitivity of the measure is demonstrated by disclosing the distinct spatial responding mechanisms of the Northeastern and Southwestern Amazon (NA, SA) to the surrounding sea surface temperature (SST) variabilities. The Pacific and Atlantic oceans have different roles on the precipitation patterns in Amazonia. More specifically, the very dry periods in the NA are influenced by El Ni\~no events, while the very dry periods in the SA are affected by the anomalously warming of the SST in the North Atlantic. We show convincingly that the drought 2005 hit SA, which is caused by the North Atlantic only. There are two phases in the drought 2010: (i) it was started in the NA in August 2009 affected by the El Ni\~no event, and (ii) later shifted the center of action to SA resulted from anomalously high SST in North Atlantic, which further intensifies the impacts on the spatial coverage.