9615316 Grotjahn Dr. Grotjahn will conduct a study aimed at better understanding the dynamics of midlatitude extratropical cyclones. Specifically, he will look at the development processes that occur within a cyclone's life cycle using several different numerical models, each of which uses a set of equations which approximates actual atmospheric dynamics based on its own set of simplifying assumptions. Dr. Grotjahn will compare the evolution of cyclone in each of these models, including how various terms of the equations evolve with time, and assess the model's effectiveness in representing the behavior of the real atmosphere. The focus of this effort will be a comparison of nonmodal growth processes and traditional baroclinic instability processes. Model results also will be compared with analyses of observations. The research will be done in collaboration with Dr. Joseph Tribbia of the National Center Atmospheric Research. ***