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URBAN MORPHOLOGICAL ANALYSIS FOR MESOSCALE METEOROLOGICAL AND DISPERSION MODELING APPLICATIONS: CURRENT ISSUES
Citation:
Burian, S., M. J. Brown, J.K S. Ching, M. L. Cheuk, M. Yuan, W. Han, AND A. T. McKinnon. URBAN MORPHOLOGICAL ANALYSIS FOR MESOSCALE METEOROLOGICAL AND DISPERSION MODELING APPLICATIONS: CURRENT ISSUES. Presented at 5th Symposium on the Urban Environment, Vancouver, BC, Canada, August 23-27, 2004.
Impact/Purpose:
The objective of this task is to develop and evaluate numerical and physical modeling tools for simulating ground-level concentrations of airborne substances in urban settings at spatial scales ranging from ~1-10 km. These tools will support client needs in the areas of air toxics and homeland security. The air toxics tools will benefit the National Air Toxics Assessment (NATA) program and human exposure modeling needs within EPA. The homeland security-related portion of this task will help in developing tools to assess the threat posed by the release of airborne agents. Both sets of tools will consider the effects induced by urban morphology on fine-scale concentration distributions.
Description:
Representing urban terrain characteristics in mesoscale meteorological and dispersion models is critical to produce accurate predictions of wind flow and temperature fields, air quality, and contaminant transport. A key component of the urban terrain representation is the characterization of the morphology of cities. This can be accomplished using 3D building and vegetation databases containing extent and height information in concert with remotely sensed data to calculate a set of morphological and surface cover parameters. Currently, morphological and surface cover parameters are unknown quantities for most locations and their values must be estimated using intuition and best guesses. In extreme cases, the necessary high resolution data for small areas is available and this information can be used to extrapolate to larger areas or areas where data is not available. However, the task of computing the parameters is time consuming and rife with uncertainties. Fundamental guidance on the necessary data resolution and the effect of aggregation is not well defined. Nor is the appropriate means established to correlate parameters to underlying nationally consistent datasets and account for parameter variability within a city and between cities when performing extrapolation. This paper will report on the analysis of urban canopy parameters computed for eight cities in the U.S. The results will focus on the variability of the parameters within each city and between cities. Results will also be reported for an assessment of data resolution effects aggregation procedures when aggregating from dataset resolution to modeling grid cell resolution.
The United States Environmental Protection Agency through its Office of Research and Development also partially funded and collaborated in the work described here. It has been subjected to Agency review and approved for publication.