9312449 Sanders The use of isentropic potential vorticity as a tool for studying the structure and evolution of synoptic-scale atmospheric phenomena is very much "in vogue". The conservation of potential vorticity is a key assumption. In a recently completed pilot study using operational analyses from the National Meteorological Center, Dr. Sanders found evidence suggesting this assumption is not valid. Under this award, he will further extend his initial study using higher temporal and spatial resolution information. As part of his investigation, he will attempt to relate changes in potential vorticity to sub-grid scale processes in the observed behavior of synoptic systems. Besides its potential for contributing to improved understanding of the physical processes involved in synoptic weather systems, the research will force the community to scrutinize and perhaps better understand the uses and limitations of so-called "PV thinking". ***
