HR: 09:00h
AN: A31D-05    [Abstracts]
TI: The Double Counting Problem in Neighborhood Scale Air Quality Modeling
AU: * Du, S
EM: sdu@arb.ca.gov
AF: Planning and Technical Support Division, California Air Resources Board, PO Box 2815, Sacramento, CA 95812 United States
AU: Hughes, V
AF: Planning and Technical Support Division, California Air Resources Board, PO Box 2815, Sacramento, CA 95812 United States
AU: Woodhouse, L
AF: Planning and Technical Support Division, California Air Resources Board, PO Box 2815, Sacramento, CA 95812 United States
AU: Servin, A
AF: Planning and Technical Support Division, California Air Resources Board, PO Box 2815, Sacramento, CA 95812 United States
AB: Air quality varies considerably within megacities. In certain neighborhoods concentrations of toxic air contaminants (TACs) can be appreciably higher than that in other neighborhoods of the same city. These pockets of high concentrations are associated with both transport of TACs from other areas and local emissions. In order to assess the health risks imposed by TACs at neighborhood scale and to develop strategies of abatement, neighborhood scale air quality modeling is needed. In 1999, the California Air Resources Board (ARB) established the Neighborhood Assessment Program (NAP) - a program designed to develop assessment tools for evaluating and understanding air quality in California communities. As part of the Neighborhood Assessment Program, ARB is conducting research on neighborhood-scale modeling methodologies. Two criteria are suggested to select a neighborhood scale air quality modeling system that can be used to assess concentrations of TACs: scientific soundness and balancing computational requirements. The latter criterion ensures that as many interested parties as possible can participate the process of air quality modeling so that they have a better understanding of air quality issues and make best use of air quality modeling results in their neighborhoods. Based on these two selection criteria a hybrid approach is recommended. This hybrid approach is a combination of using both a regional scale air quality model to assess the contributions from sources that are not located within the neighborhood of interest and a microscale model to assess the impact from the local sources that are within the neighborhood. However, one of the modeling system selection criteria, balancing computational requirements, dictates that all sources (both within and outside the neighborhood of interest) must be included in the regional scale modeling. A potential problem, referred to as double counting, arises because some local sources are included in both regional and microscale modeling. To address this issue, a box model is developed to calculate the impact of double counted sources so that their effect on the total concentration (i.e., concentration due to all sources) can be minimized or even eliminated.
DE: 0345 Pollution--urban and regional (0305)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting