Diagnostics of the Mechanisms that Control the Interannual Variations of the South American Climate and Its Connection to Climate over North America

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This project is an investigation of factors that influence the start and end of the rainy season in tropical South America and hence influence agricultural productivity and the availability of water resources. The objectives are: (i) to determine the influence of large-scale circulation anomalies, especially those forced by interannual variations of sea-surface temperatures in the adjacent oceans, on the key thermal and dynamic factors that control the onset and demise of the rainy season over the northern part of South America, (ii) to explore how land-surface processes and bio-mass burning modify the atmospheric boundary layer conditions needed for the onset of the rainy season by influencing pre-seasonal climate conditions, (iii) to characterize the link between regional climates in tropical South America, Central and North America via cross-equatorial flow and to identify the underlying dynamic processes. The approach to be taken consists of a diagnostic study of a number of data sets relevant to the climatology of the region. The data include: ECMWF reanalyses, South American rain gauge data, in situ surface fluxes and soil moisture from the Large Scale Biosphere-Atmosphere Experiment in Amazonia, instantaneous cloud data from the International Satellite Cloud Climatology Project, aerosol optical depth from the Total Ozone Mapping Spectrometer, and the NASA-Ames 8-km Amazon Ecology Mapping data.