Site-to-Site Variation in Performance of Dispersion Parameter Estimation Schemes

Abstract

To promote better practices in air pollution modeling, the American Meteorological Society sponsored a workshop on stability classification schemes and sigma curves (Hanna et al., 1977). The participants at this workshop reviewed the bases and limitations of the popular dispersion parameter schemes and suggested that the standard deviation of the crosswind concentration distribution, ^σ _y, might be viewed as

$${\sigma _y} = {\sigma _v}\;\;t\;{f_y},$$

((1))

, where ^σ _y is the standard deviation of the horizontal crosswind component of the wind, t is the downstream travel time and f_y is a nondimensional function. The standard deviation of the vertical concentration distribution, ^σ _z, was viewed as

$${\sigma _z} = {\sigma _w}\,\,t\;\;{f_z},$$

((2))

, where^σ _w is the standard deviation of the vertical component of the wind, and f_z is a nondimensional function. Small-angle approximations, such as ^σ _v t = ^σ _a X and ^σ _w t = ^σ _e X (where ^σ _a is the standard deviation of the horizontal wind angle, ^σ _e is the standard deviation of the vertical wind angle, and X = u t), allow restatement of (1) and (2) in various forms.

On assignment from the National Oceanic and Atmospheric Administration, U.S. Department of Commerce