IMPLEMENTATION OF AN URBAN CANOPY PARAMETERIZATION IN MM5

摘要

The Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) (Grell et al. 1994) has been modified to include an urban canopy parameterization (UCP) for fine-scale urban simulations (~1-km horizontal grid spacing).The UCP accounts for drag exerted by urban structures, the enhancement of turbulent kinetic energy (TKE) especially near the tops of the buildings, and the modification of the energy budget within the urban canopy (i.e., from the surface to the tops of buildings). This UCP is applied to grid cells in MM5 that have a non-zero fraction of urban land use. This refinement of MM5 is targeted to enable the Community Multiscale Air Quality (CMAQ) Modeling System (Byun and Ching 1999) to capture the details ofpollutant spatial distributions in urban areas.