Almost two-thirds of the U.S. population live in urbanized areas occupying less than 2% of the landmass (Carbone 2000). Similar statistics of urbanization appears all over the world. As a result, the interaction between the urban infrastructure and atmospheric processes becomes a multi-dimensional problem in scope (Dabberdt et al. 2000). Further understanding of this interaction via the surface and/or atmospheric processes is of importance to improve weather forecast skill, and to minimize the loss caused by the weather related events (such as air quality, surface hydrology, the intensity and movement of precipitating storms, and transportation safety), or even by the chemical-biological threat. To this end, an urban canopy parameterization to include drag, turbulent production, radiation balance, and anthropogenic and rooftop heating effects has been developed and tested in a sensitivity study for an idealized case using a mesoscale model (Chin et al., 2000). Our results indicate that the addition of rooftop surface energy equation enables this urban canopy parameterization to simulate the impacts of urban infrastructure more realistically.

To further evaluate the performance of this urban canopy parameterization, simulations will be conducted using the Naval Research Laboratory mesoscale forecast model (COAMPS) and compared with the field measurements from the Department of Energy field campaign at the Salt Lake City, October 2000 (Allwine et al., 2001). The intensive observational period of IOP-10 occurring on October 25, 2000 is selected in this study as a representative of the high wind case. Using a look-up table approach, urban infrastructure parameters (such as urban fraction, roof fraction, building height, and anthropogenic heating) and urban surface characteristics (such as albedo, wetness, and roughness) can be derived from the USGS land-use data with the resolution of 200 and/or 30 meters. These parameters will be used as inputs to drive our urban canopy parameterization. Simulations with urban infrastructure and/or urban surface properties enable us to gauge the overall urban impact of individual aspect. The objective of this study is focused on the mesoscale aspect of the urban effects.