Historical drought and monitoring over South America

South America strongly depends economically on its agricultural resources that in turn are greatly sensitive to climatic extremes. According to the United Nations International Disasters Risk Reduction, Brazil was ranked the sixth country on natural disasters in 2009 including severe droughts. Drought events around the world are often characterized by the Palmer Drought Severity Index (PDSI), originated from studies in the United States. It requires as little as precipitation and temperature and its parameters have been extensively adjusted for regions in North American. In South America, there are few initiatives of applying PDSI. However, a great number of useful drought characterization indexes such as Standardized Precipitation Index (SPI), soil moisture anomalies and streamflow statistics, among others, although PDSI still gives a reasonable characterization of the terrestrial water balance since it uses minimum statistics. This study presents a continental scale drought characterization within the recent observational record, using a CRU-based dataset of near surface atmospheric variables from 1948-2008 over South America. In addition to PDSI other methods such as SPI, soil moisture and precipitation percentiles and streamflow analysis will be presented. Particular emphasis is given to the relationship between drought and El Nino/La Nina events and also the 2005 drought in Amazonia.