Understanding Intraseasonal Convection and Large-Scale Circulation Variations in Observations and Climate Models

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This project is designed to improve our understanding of the interactions between tropical convection and the large-scale circulation, focusing particularly on the Madden-Julian Oscillation (MJO). Three mechanisms by which MJO convection may be linked to the large-scale circulation are to be studied: surface wind convergence, tropospheric moisture variations, and surface evaporation variations. Observational work includes the role played by tropospheric moisture variations in influencing intraseasonal convection, the importance of variations in surface evaporation in determining the character and location of sub-seasonal convection, the dependence of intraseasonal convection on surface wind convergence imposed by the large-scale flow, and the mechanisms which determine the strong relationship among tropical synoptic-scale disturbances, tropical cyclone variability, and sub-seasonal wind variations. A comparison of model performance to observations will enable progress toward an improved convective parameterization. These activities are to be coordinated with the Atmospheric Model Working Group at National Center for Atmospheric Research which is responsible for developments in the atmospheric component of the Community Climate System Model, version 2.0.Broader impactsThis research will support one student. It will add to the body of knowledge of the Madden-Julian Oscillation in particular, and to the understanding of the interactions of convection and large-scale circulation in general. The results will be disseminated via meetings and publications in internationally-recognized scientific journals.