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  • Author or Editor: GEORGE C. HOLZWORTH x
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George C. Holzworth

Abstract

The plume rise equations of Briggs (1975) for variable vertical profiles of temperature and wind speed are described and applied for hypothetical short and very tall chimneys at five National Weather Service rawinsonde stations across the United States. Annual average effective chimney heights are presented and from other available data additional information on plume behavior is deduced. For example, based on the 0515 CST soundings at Nashville, 61% of the effective plume heights for 50 m chimneys were in a temperature inversion, but only 21% of the plumes for 400 m chimneys were so constrained. Ordinarily, such plumes would be in a fanning configuration. Most of the plumes from tall chimneys (60%) were above an inversion, practically isolated from the ground. Overall, 98% of the short-chimney plumes were reached by the afternoon mixing height, but only 85% of the tall-chimney plumes were reached. Such information supports the obvious presumption that the effluent from tall chimneys remains airborne longer than that from short chimneys, is transported over greater distances, and has more opportunity to undergo chemical transformations before reaching the ground.

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George C. Holzworth

Abstract

Daily estimates of morning and afternoon mixing depths and average wind speeds through the mixing layers were calculated and summarized for seven locations in several climatic regions of the contiguous United States. Mixing depth and wind speed estimates were based on regular surface (airways) and upper air (rawinsonde) observations of the Weather Bureau and on the assumption of a dry-adiabatic lapse rate in the mixing layer. Monthly averages of morning and afternoon mixing depth and wind speed are presented graphically. The frequency of occurrence of various combinations of mixing depth and wind speed classes were used in an urban diffusion model to calculate theoretical values of relative pollutant concentration for four major cities. These relative pollutant concentrations, which also depend upon city size, are compared among the cities on the bases of their current sizes and a common size.

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George C. Holzworth

Abstract

The climatological occurrence of meteorological conditions associated with extensive and persistent arms of high air pollution potential over the western United States is presented. The most likely large-scale synoptic feature conducive to poor air quality is found to be the quasi-stationary anticyclone. A typical episode of high pollution potential is described. The forecasting of such episodes, including some inherent difficulites, is discussed.

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