Climate diagnostics of three major drought events in the Amazon and illustrations of their seasonal precipitation predictions

Abstract

Abstract The Amazon has a well‐defined wet austral summer monsoon and dry winter monsoon precipitation regime and experienced a sequence of drought events in the last 13 years. This study performs a comparative assessment of observed and predicted climate conditions during the three most recent drought events in the Amazon, in 1997–1998, 2004–2005 and 2009–2010, with emphasis on how these events affected the regional monsoon‐like precipitation regime. A century long Negro River level time series at Manaus is investigated, applying extreme values theory for estimating return periods of these major drought events. Possible teleconnections of river levels at Manaus and sea surface temperature at remote regions are explored. Large scale oceanic and atmospheric conditions are investigated to highlight the mechanisms associated with the observed drought conditions, particularly during the dry monsoon season. Satellite estimates are used for diagnosing biomass burning aerosol and discuss possible contributions to the observed precipitation deficits in the 2005 and 2010 drought events during the dry monsoon season. The study is concluded with an analysis of the performance of seasonal precipitation predictions for the dry monsoon seasons of July to September 1998, 2005 and 2010 produced with the operational seasonal prediction system used at the Center for Weather Forecasts and Climate Studies (CPTEC) of the Brazilian National Institute for Space Research (INPE). This system was capable of producing 1 month in advance drought warning for the three investigated events, relevant for helping the government and local population make decisions for reducing drought impacts in the Amazon region. Copyright © 2012 Royal Meteorological Society