Sylvia Sullivan
Department of Earth and Environmental Engineering
Columbia University
Title: Changes to tropical organized convection and its precipitation with El Niño
Abstract: Convective organization on the mesoscale can bring the majority of precipitation in certain tropical regions and has a large radiative impact through extensive anvil outflow. We have been investigating how the structure and rainfall of these systems vary during El Niño versus La Niña. Because climate models do not yet represent convective organization at this scale, a theoretical assessment of such variations has not been possible. We instead use collocated satellite observations (ISCCP) and reanalysis values (ERA-Interim) to build climatologies of convective coverage and depth, associated precipitation accumulation and intensity, as well as lifecycle and organization metrics. Using a zero-buoyancy plume framework, we investigate the roles of entrainment and convective available potential energy in precipitation trends from convective systems of different vertical depth. More aggregated convection and the largest relative gains in precipitation intensity from deep systems occur during El Niño, with hydrological implications for a warming world where intense El Niño occurrence is more probable.
Joint work: S. Sullivan and P. Gentine, Environmental Engineering, Columbia University
Host: Pierre Gentine
