Intellectual Merit: This research focuses on the analysis of the spatial scale dependence of convection, cloud microphysics, and fractional cloudiness, from the results of short-term experiments with varying resolutions using the Weather Research Forecast (WRF) model. First, the Principal Investigator will implement a set of unified prognostic parameterizations that simulate moist convective and cloud microphysics processes, from cloud resolving to low resolution regional modeling scales. Second, a series of numerical experiments will be run with decreasing horizontal resolutions with the aim to define the spatial scale at which parameterized convection and fractional cloudiness are both needed. The numerical experiments will be run over the Continental United States for which observations and small-scale forecasts are abundant and readily available.
The research aims at quantifying the impact of horizontal resolution on the simulations of cloud systems in WRF, using parameterizations of moist processes which interact between each other in a consistent manner. Using a high resolution numerical experiment as a reference, the research addresses the questions 1) What is the horizontal resolution at which parameterized convection becomes needed, and how to best simulate interactions between convection and cloud microphysics processes?; and 2) What is the horizontal resolution at which parameterized fractional cloudiness becomes needed, and how to best simulate the cloud amount as a function of cloud microphysics sources and sinks?
Broader Impacts: The research addresses the need of the WRF Users' community by providing a set of parameterizations of moist processes that were consistently developed, and can be used at different horizontal scales.
