Abstract

Weather and air quality models and model inputs and physics options for mesoscale and urban scale simulations are briefly reviewed including current understandings, especially of model issues, specialized data inputs and emerging new physics parameterizations for fine grid mesh simulations. Such models provide powerful means to perform air quality forecasting, planning and assessment applications especially when employing increasingly finer grid meshes for urban applications. To illustrate, examples from sensitivity study simulations based on the WRF and CMAQ modeling systems as applied to the Houston Texas area will be presented. We note from observations the presence and persistence of quasi-stationary mesoscale structures of mixed layer origins for weakly forced flows. This situation provides an important context for examining model requirements and performance for urban applications. Additionally, to take advantage of increasing experience and capability to model at fine scales, a conceptual framework is described that can provide sub-grid scale weather and pollutant concentration distributions (or parameterizations) to coarser grid operational weather and air quality models.