Title

Persistence Factors For Mobile Source (Roadway) Carbon-Monoxide Modeling

Comments

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Keywords

Engineering; Environmental; Environmental Sciences; Meteorology; Atmospheric Sciences

Abstract

A critical step in the modeling of the carbon monoxide (CO) impacts of mobile sources is predicting an 8-hour CO concentration given a modeled "worst-case" 1-hour concentration. Often, this is done by a multiplicative persistence factor. A meteorological persistence factor (MPF) accounts for the variability over 8 hours of wind speed, wind direction, stability class, and temperature. A vehicular persistence factor (VPF) reflects the lower traffic volumes during the off-peak hours.

Hourly meteorological data for ten years for four cities in Florida were obtained from the National Climatic Data Center. The CALINE3 model was used to obtain hourly CO concentrations, which were combined to derive MPFs for each city. Similarly, VPFs were derived from hourly vehicle counts from one busy roadway in each city. The mean VPF multiplied by the second highest MPF was defined as the worst-case total persistence factor (TPF). These worst-case TPFs increased significantly as more hours of nighttime were included in the 8- hour averaging time, but were fairly consistent from city to city. In general, the results suggest worst-case TPFs in the range of 0.4 to 0.5, lower than has been recommended by EPA in the past.

Journal Title

Japca-the Journal of the Air & Waste Management Association

Volume

39

Issue/Number

5

Publication Date

1-1-1989

Document Type

Article

Language

English

First Page

714

Last Page

720

WOS Identifier

WOS:A1989U618700006

ISSN

0894-0630

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