DAQM-Simulated Spatial and Temporal Differences Among Visibility, PM, and Other Air Quality Concerns Under Realistic Emission Change Scenarios

Abstract

The Denver Air Quality Modeling Study (DAQMS) is a comprehensive modeling effort originally undertaken to apportion sources of visibility degradation and examine the visibility benefits of future emission strategies in the Denver metropolitan area. Because of the detailed treatment of the chemical and physical processes and high temporal, vertical, and horizontal resolution of the system, it is possible to examine other air-related issues and their relationships to visibility. The DAQMS analysis system consists of the Denver Air Quality Model (DAQM), a three-dimensional Eulerian chemical-transport model including aerosol and gas-phase transport and transformation processes, a three-dimensional mesoscale meteorological modeling system, visibility analysis procedures, and an emissions processing system. DAQM, the meteorological model, and the emissions information operate on a domain covering approximately the entire state of Colorado with 8-km grid resolution and 15 vertical levels from the surface to the stratosphere. Analysis from a winter visibility episode illustrates the differences between spatial and temporal distributions of light extinction, fine and coarse particle aerosol concentrations, oxidants, and carbon monoxide under various emission scenarios. Studies aimed at exploring interrelationships between these air quality concerns for different seasons, meteorological conditions, and emission management scenarios are outlined.