This award provides continuing support for a broad research program aimed at improving numerical models of tropospheric and stratospheric circulations. The long-term benefit will be the improvement in our ability to predict weather and climate. The project consists of three major thrusts. The first involves a variety of problems related to dynamical and computational aspects of atmospheric modeling, with the focus being the development, application, and evaluation of an isentropic coordinate model. Using an isentropic coordinate system allows one to overcome certain computational problems associated with other coordinate systems which can affect the accuracy of the representation of dynamical processes in the model. Another exciting part of this activity is the construction of a hybrid-coordinate model that combines the isentropic model with a variable depth planetary boundary layer model. The second major area involves the parameterization of subgrid-scale processes involving (1) orography, and (2) moisture, with emphasis on the three-way interactions between convective-scale, mesoscale and large-scale circulations under various types of flow patterns and surface boundary conditions. This will be done as a combination of statistical studies of observed conditions and numerical simulations. Finally, the principal investigators will incorporate a number of the new parameterizations into the UCLA general circulation model.
