The Effect of Moist Physics and Resolution on Baroclinic Wave Evolution in an Idealized Simulation

The role of parameterized moist physics processes in extratropical cyclone evolution and predictability is still not completely understood. The focus of this research it to determine the physical and dynamical mechanisms by which "errors" in thermodynamic tendencies from microphysics, radiation, and cumulus parameterization schemes are communicated to the grid-scale and the impact of those "errors" on the synoptic-scale forecast. Previous studies have approached this problem using case studies that include the full physics of a typical operational model. The added realism of using case studies adds difficulty in determining sensitivity systematically due to the added complexity of parameterizing surface fluxes and boundary level effects as well as topography and surface friction. For this study I have run an ensemble of 20 simulations of an idealized baroclinic wave using the Weather Research and Forecasting model. Ensemble members are generated by running 5 simulations using no physics parameterization, microphysics only, microphysics and radiation only, and finally 2 different runs with microphysics, radiation, and cumulus parameterization. Each set of simulations is run at 100KM, 20KM, 10KM, and 4KM to determine the potential impacts of resolution on the evolution of errors in thermodynamic tendencies as well. By partitioning the contribution of diabatic potential vorticity(PV) tendencies from the total potential vorticity tendency, I have found significant differences in the evolution of the lower tropospheric PV anomolies due to changes in the physical processes parameterized. This research will determine the physical and dynamical mechanisms causing these differences.