PM10 modeling for the Thurston County redesignation request
- Systems Applications International, San Rafael, CA (United States)
Present dispersion modeling procedures for assessing particulate matter for air quality planning purposes have historically relied upon Gaussian-based dispersion models such as RAM and ISC. These tools were useful when particulate matter violations were associated with point source emissions or violations of the annual standard. However, most PM{sub 10} exceedances today are the result of areawide emissions as well as point sources a more realistic treatment of dispersion processes is warranted. High 24-hour average PM{sub 10} concentrations throughout the western US frequently occur during fall and winter under low wind speed, stable conditions. These are the same conditions under which steady-state assumptions of Gaussian formulated models are invalid. Because the steady-state Gaussian based approach cannot simulate the accumulation of material from hour to hour large discrepancies occur between modeled and observed concentrations. A grid cell and time step modeling approach of the UAM model is more appropriate for episodic particulate modeling. The UAM model is well suited because it can numerically simulate the effects of emissions, advection (at wind speeds well below 1.0 ms{sup {minus}1}), carryover and diffusion and removal processes. As part of the Thurston County PM{sub 10} maintenance demonstration the UAM model was applied for both PM{sub 10} and PM{sub 2.5}. CMB analysis has shown that nearly all of the observed PM{sub 10} is the result of primary emissions, correspondingly the UAM model was applied without particulate chemistry. In this mode the model is computationally inexpensive and easily runs on a PC-platform.
- OSTI ID:
- 351008
- Report Number(s):
- CONF-970677-; TRN: IM9925%%170
- Resource Relation:
- Conference: 90. annual meeting and exhibition of the Air and Waste Management Association, Toronto (Canada), 8-13 Jun 1997; Other Information: PBD: 1997; Related Information: Is Part Of 1997 proceedings of the Air and Waste Management Association`s 90. annual meeting and exhibition; PB: [7000] p.
- Country of Publication:
- United States
- Language:
- English
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