The project applies a balance of observational diagnosis and model experimentation to try to improve our understanding of fundamental features of tropical intra-seasonal variability (ISV) to improve the simulations of these features in global atmospheric models. This is to be accomplished by examining the coupling mechanism between ISV-associated precipitation, wind speed and latent heat flux anomalies, and the modulation of tropical synoptic-scale variability by the ISV. Observation-based studies focus on examination of the coupling between ISV-related precipitation, wind speed, and surface heat flux anomalies and their relation to shorter synoptic-scale variations using satellite data. Model sensitivity studies will focus on mechanisms of moisture-convection feedback, moisture-radiation feedback, wind-evaporation feedback, and the role of ocean-atmosphere coupling using ocean models of varying complexity. Broader impacts include graduate student training and curriculum enhancement.