Abstract

A principal goal of the Climate Prediction Center (CPC) is to monitor climate variability for the Americas on time scales ranging from diurnal to interannual. As an important step towards this, we have recently developed a South American precipitation quality control (QC) system and analysis which is applied to both real-time and historical raingauge data sets. At the present, the historical daily precipitation analysis covers only Brazil (1960-present), while the realtime analysis covers the entire continent (1998-present).

A time series representing El Niņo-Southern Oscillation (ENSO) is used together with observed daily precipitation data over Brazil to diagnose relationships between climate variability and precipitation extremes on a seasonal basis. The study highlights the connections between ENSO and the statistics of daily precipitation events (including frequency, intensity and geographic distribution). Large-scale circulation features associated with extreme precipitation events in the most sensitive regions are examined in detail. Emphasis is placed on linkages between daily precipitation and climate variability that meteorological models must be able to simulate in order to be deemed credible for use in weather and climate forecasts and assessments.