George Mason University
In the 1960s, the atmospheric science community began looking seriously at how cities affect the natural climate system. In the 1970s a number of groundbreaking urban field experiments were conducted, partially in response to air quality concerns in large metropolitan cities. Unlike, in the 60s and 70s, in recent years computer models are now being used to understand the dynamics of urban-induced circulations and heating patterns. Based on these studies, the urban climate system was found to be multi-dimensional and complex with numerous feedback mechanisms between components. As a result, modeling the impact of urban environment in mesoscale models is a special and an important challenge. Cities affect the local and regional scale weather by perturbing the wind, temperature, moisture, turbulence, and surface energy budget fields. Effective mitigation of hazard releases in urban settings is predicated upon an understanding of transport and dispersion processes within urban settings. These understandings must be incorporated into the physics of operational mesoscale models.
This talk will discuss field observations regarding the urban influence on local meteorology. A brief survey of prior work on mesoscale modeling of urban areas will be presented. Then, an application of urban parameterization scheme that accounts for effects due to drag, turbulent production, radiation balance, and root-top heating will be discussed. Finally, problems that arise when implementing or validating the urban canopy parameterizations will be discussed.