Vertical Structure and Diabatic Processes of the MJO: Initial results from the 2-day hindcasts

A Joint Research Activity by the WCRP-WWRP/THORPEX MJO Task Force & Year of Tropical Convection (YOTC) and the GEWEX Atmosphere System Study (GASS) is in progress to characterize, compare and evaluate the heating, moistening and momentum mixing processes associated with the MJO that are produced by global weather and climate models, with a particular focus on their vertical structure. Three sets of experiments are conducted i) twenty-year climate simulations ii) a series of daily initialized 2-day hindcasts for two successive MJO events during boreal winter 2009-10 which focuses on detailed model output over a select near-equatorial Indian Ocean / western Pacific Ocean domain and iii) 20-day hindcasts to assess the performance of the models MJO as a function of forecast lead time.

Analysis of the 2-day hindcast component focuses on processes that control transition from suppressed to active convective phase over the Indian Ocean. 12-36 hours of the forecast has been analysed to provide a balance between minimizing the spin up effects and minimizing the differences in the large scale evolution. Results from the analysis of vertical humidity structures, cloud variables and heating and moisture budgets will be presented.