An examination of the Pasquill-Gifford-Turner dispersion scheme

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:422877

Venkatram, A ^[1]

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1. Univ. of California, Riverside, CA (United States). Coll. of Engineering

In the US, air pollution models find their greatest application in the implementation of air quality regulations. These models usually incorporate the Pasquill-Gifford-Turner (PGT) curves to estimate horizontal and vertical spreads of a plume at spatial scales less than 10 kilometers. In view of the wide-spread acceptance of the PGT dispersion estimates, it is worthwhile to examine their basis in the light of current understanding of dispersion in the surface boundary layer. The PGT curves were developed about thirty years ago through empirical analyses of observations from field studies of dispersion in the surface boundary layer. Since their development, understanding of dispersion as well as micrometeorology has progressed to the point that one can find reliable estimates of dispersion from sources in the surface layer. However, the methods to make these estimates have not been incorporated into the practice of modeling primarily because it is generally believed that the PGT curves provide useful concentration estimates suitable for regulatory decisions. This paper examines this contention by first examining the theoretical basis of the PGT curves in the light of current understanding of dispersion in the surface boundary layer. The author then compares PGT estimates of dispersion with those from current theory. He has not conducted a similar examination of horizontal spreads because the understanding in this regard is still uncertain. The author begins with a brief description of the PGT scheme.

• OSTI ID: 422877
• Report Number(s): CONF-960127--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
ENVIRONMENTAL TRANSPORT
MATHEMATICAL MODELS
METEOROLOGY
PLUMES