9310119 Pfeffer Drs. Pfeffer and Challa will continue their investigations into the physical processes responsible for hurricane formation, pursuing two major thrusts. The role of environmental forcing in the transformation to cloud clusters and depressions into hurricanes will be explored using potential vorticity diagnostics of model simulations. Specifically, the PIs will look at the relative important of upper level atmospheric waves and low level wind surges in the hurricane genesis. The other principal effort will be to assess how the representation of boundary layer and cumulus cloud processes affects simulations of hurricane development through sensitivity studies with various parameterization schemes. In addition, they use a coupled atmosphere-ocean model to investigate how variations in thermocline depth affects tropical cyclone development. This research is an important contribution to improving our ability to better predict hurricane development and behavior. ***