Dynamics of the Tropical Troposphere

Colorado State University, Fort Collins CO

Investigators

Abstract

This project addresses several research topics that are relevant to the dynamics of hurricanes and the intertropical convergence zone (ITCZ). The objectives of the research are to increase the dynamical understanding of these tropical phenomena and to improve the accuracy of numerical simulations of tropical circulations. Recently developed dynamical theories are built upon and extended, and a hierarchy of numerical models will be utilized to achieve the objectives of the research. Previous studies of meso-vortices and rapid surface pressure falls associated with potential vorticity mixing in hurricanes will be extended to three dimensional numerical modeling with better physics equations to provide a more complete analogy to the flow of real hurricanes. Ice effects and microphysical aspects will be studied in the framework of the extended model. This will lead to better understanding of hurricane near-core dynamics. The simulation of the ITCZ and Hadley circulation will be extended to include moist dynamics and will be done at high resolution, because observations of surface winds suggest that vorticity structures within the ITCZ exhibit fine-scale structures. These may affect the undulation and breakdown process of the ITCZ. Another hierarchy of models will be employed to study the large-scale dynamical controls of water vapor in the tropics and subtropics. Observational data from field experiments will be used in conjunction with the theoretical and numerical work. Broader impacts of the development of the theory of moist dynamics will cover a wide range of applications in tropical meteorology. This will eventually lead to improved forecasting of tropical cyclones and of intensity changes of hurricanes. The part of the work related to water vapor fields will lead to improved weather prediction in areas where astronomical equipment is stationed. There will be a considerable impact on graduate student education by giving students access to a hierarchy of numerical models.