The overall goal of this project is to better understand the development of synoptic scale weather systems, which may ultimately lead to improved weather forecasts. The principal investigator's previous work has focused how the structure of the flow, or "initial value", contributes to subsequent development of perturbations. He will extend this research along two lines. The first thrust is to continue his investigations into the physical mechanism(s) responsible for cyclogenesis; the other is to explore the predictability of large scale atmospheric flows. Observational evidence suggests that deformation, as well as shear, in the background atmospheric flow plays an important role for certain types of cyclogenesis. The principal investigator already has shown the effect of shear in the background flow on the energetic development of cyclones. He will extend this work to look at the effect of confluence and difluence on perturbations in the flow. While the subject has been studied extensively, theoretical estimates of the predictability of the atmosphere still vary widely as do the results from numerical weather prediction experiments. The reason appears to be variability in the predictability of the flow regimes, that is, certain types of flows are inherently more predictable than others. The principal investigator will explore the growth of error in numerical models and attempt to distinguish between those flows which are predictable and those which are not as a function of flow characteristics.
