Application of a New Land-Surface, Dry Deposition, and PBL Model in the Models-3Community Multi-Scale Air Quality (CMAQ) Model System

摘要

Like most air quality modeling systems, CMAQ divides the treatment ofmeteorological and chemical/transport processes into separate sequentially. A potential drawback to this approach is that it creates the illusion that these processes are minimally interdependent and that any meteorology model with a good reputation is adequate for air quality work. However, most mesoscale meteorology models are developed for operational weather forecasting and meteorological research. These foci do not emphasize all the same critical capabilities as air quality applications. Conversely, CTMs are often developed to accept basic meteorology inputs from a variety of sources with little regard to its quality and even less regard to consistency between physical parameterizations in the meteorology model and the CTM. The work reported here attempts to address some of these weak links in the system, particularly where improvements in land-surface modeling in the meteorology model and consistency with similar components in the CTM can have significant effects on the air quality simulation. Therefore, this development cuts across several system components. A new land-surface model (LSM), which features explicit simulation of soil moisture and vegetative evapotranspiration, has been coupled with the Fifth Generation Penn State/NCAR Mesoscale Model (MM5). An attendant dry deposition model has been developed to take advantage of the more sophisticated treatment of surface fluxes, stomatal conductance, and surface layer diffusion in the new LSM. The Meteorology Chemistry Interface Processer (MCIP) has been modified to include the new dry deposition model as well as to make the additional information resulting from the new LSM available to the CTM. Also, a new non-local closure PBL scheme that is compatible with the modifications made to the MM5 has been added to the list of vertical diffusion module options of the CMAQ CTM.