Urbanization of meteorological models: implications on simulated heat islands and air quality
In most meteorological models, urban and non-urban areas are treated mostly similarly, e.g., through similar sub-surface, surface, and boundary-layer formulations. No different/additional mechanisms or physics exists to account for urban specific dynamics and energetics and for their impacts on the planetary boundary layer. However, recent efforts have suggested various modeling approaches to link the different physics of the canopy and urban boundary layers. This paper briefly reviews the issue of model urbanization. A review of approaches taken to date is presented. The paper then focuses on one such aspect, that is a formulation we propose for improved prediction of urban air temperature fields. Results from applying a modified (urbanized) model to a Northern Georgia domain are discussed with particular emphasis on urban heat island magnitude and related impacts on emissions and ozone production. Application of the modified (urbanized) model produced a larger simulated Atlanta heat island, which then resulted in increased biogenic volatile organic compounds (e.g., isoprene) emissions by 10% and in accelerated photochemical production of ozone by about the same amount.