The goal of this research is to better understand the nonlinear dynamics and evolution of atmospheric disturbances embedded in a zonally varying basic flow. The research will be done using a two-layer baroclinic model on the beta-plane and a spherical coordinate barotropic model. The two-layer model will allow the PIs to examine baroclinic, barotropic and topographic processes and to assess the their combined role in determining the regional character and time variability of the zonal flow and wave disturbances. The research with the barotropic model will to assess the impact of using spherical geometry in simulating these types of flows. In cases of weak nonlinearity, model solutions will be obtained analytically using asymptotic expansions and multiple space and time scales. Outside this limit, spectral transform methods will be used to obtain solutions numerically. These investigations may provide further insight into such observed atmospheric features as regional cyclogenesis, blocking, and low frequency variability. This project is being carried out in collaboration with Dr. Terrence Nathan, Iowa State University, under NSF grant ATM-8813296.
