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Modeling the impact of roadway emissions in light wind, stable and transition conditions
Citation:
Venkatram, A., M. Snyder, AND V. Isakov. Modeling the impact of roadway emissions in light wind, stable and transition conditions. TRANSPORTATION RESEARCH PART D. Elsevier Science BV, Amsterdam, Netherlands, 24:110-119, (2013).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s)Atmospheric Modeling Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
This paper examines the processes that govern air pollution dispersion under light wind, stable and transition conditions by using a state-of-the-art dispersion model to interpret measurements from a tracer experiment conducted next to US highway 99 in Sacramento in 1981–1982 during the early morning and late evening when winds were light and variable. We examine the roles of stability, wind meander, and boundary layer height on concentrations measured during this study. Our analysis suggests that currently used equations for vertical plume spread need modification when the winds are light. The shallow boundary layer associated with these conditions limits vertical mixing and hence reduces the rate at which concentrations fall off with distance from the road.