Fine scale CMAQ modeling driven by urbanized MM5 and WRF models

This presentation addresses the sensitivity of air quality models that are driven by outputs of meteorological models designed for urban applications. Advanced boundary layer formulations which have explicitly introduced parameterizations of urban structures have recently been developed and implemented into several modeling system, including the MM5 and WRF. These formulations are entered as gridded parameterizations representing urban morphological features such as building and street canyons that are provided for in the National Urban Database and Access Portal Tools (NUDAPT). In this study, we compare model output differences depending on the degree and manner to which models introduce such fine scale urban structures. We subsequently examine the sensitivity of an air quality model, CMAQ to these differences. Preliminary results have already indicated large differences in CMAQ outputs when comparing results of MM5 fields with and with out the use of urban canopy formulations. Here, we examine and explore the relative impact on CMAQ from differences between advanced urbanized models that utilize different sets of UCPs formulations and grid sizes. The study venue is the TEXAS 2000 study during which high photochemical oxidation episodes occurred under complex, and where difficult-to- accurately-model flow conditions prevailed. This is a collaborative effort of the NUDAPT Houston Prototype.