Contribution of Extreme Convective Storms to Rainfall in South America

The contribution of extreme convective storms to rainfall in South America is investigated using 15 years of high-resolution data from the TRMM Precipitation Radar. Precipitation from three types of storms with extreme horizontal and vertical dimensions have been calculated and compared to the climatological rain. The tropical and subtropical regions of South America differ in the influence of storms with extreme dimensions. The tropical regions, especially the Amazon basin, have aspects similar to oceanic convection. Convection in the subtropical regions, centered on La Plata basin, exhibits patterns consistent with storm life cycles initiating in the foothills of the Andes and growing into larger mesoscale convective systems that propagate to the east. In La Plata basin, convective storms with a large horizontal dimension contribute ~44% of the rain and the accumulated influence of all three types of storms with extreme characteristics produce ~95% of the total precipitation in the austral summer. The relationship between the mesoscale convective systems and their synoptic and mesoscale environments will be presented, including a conceptual model for convection initiation and growth.