Deep Convection in the Tropics

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This award aims to increase the understanding of the interaction of deep convection over tropical oceans with weather disturbances such as tropical depressions, easterly waves, various convectively coupled equatorial wave modes, and the Madden-Julian oscillation. This is a particularly good time to undertake such a project for two reasons:1) Recent field programs, including two on tropical cyclogenesis (TPARC/TCS08 and PREDICT and one studying the Madden-Julian oscillation (DYNAMO), have provided a wealth of new, quantitative data on tropical deep convection. These observations (especially those on tropical cyclone formation) provide detailed measurements of convective mass fluxes as well as the thermodynamic and wind environments in which the convection is embedded.2) The use of the weak temperature gradient (WTG) approximation to provide lateral boundary conditions for cloud-resolving models of convection has developed to the point where the resulting calculations provide useful comparisons with observation. Preliminary results show that the model exhibits significant skill in replicating vertical mass flux profiles of observed convection, given the thermodynamic environment surrounding the convection. Work remains to be done on the comparison of mass fluxes observed in various pre-cyclone cases with WTG computations. Momentum fluxes in shear will also be explored. In addition, the PIs are just beginning our comparisons with results from large-scale tropical experiments such as DYNAMO. In addition to DYNAMO, there exists a large set of earlier observations begging to be explored.In the proposal outlines two ways that the WTG technique can be improved. One involves adding more realistic thermodynamics to the cloud-resolving model while the other consists of improving WTG?s transient behavior. These improvements are designed to result in greater fidelity in the representation of tropical convection in the model.This award has the potential to improve parameterization of convection in global models. Inadequate representation of convection in global atmospheric models is one of the main obstacles preventing progress in the forecast of tropical weather. Better weather forecasts in the tropics feed back on weather predictions over the continental United States. Climate models also suffer from this problem. Continuation of a collaboration with the University of Split, Croatia serves the goal of increased the scientific interchange between the two countries. New Mexico Tech is an hispanic-serving institution.