Development of vertical dispersion coefficients for deep-valley terrain. [Aerosol particle transport model]

VALMET-A valley air pollution model

“…The diffusion coefficients in the model need improvement. At present we are modifying Pasquill-Gifford [43] flat terrain coefficients on the basis of the Huntington canyon data of Start et al [20] and other data summarized by others [29][30][31]. We need to look at mare data or conduct specific diffusion experiments to determine the most appropriate values of these coefficients.…”

“…The present version uses Pasquill-Gifford dispersion coefficients, sigma y and sigma z, calculated using McMullen•s [28] method. The atmospheric stability used in the calculations is adjusted to account for enhanced dispersion observed in complex terrain situations by a number of other investigators[20,[29][30][31]. The resulting concentration calculations are adjusted for standard pressure and temperature.InputsThe subroutine requires information on the coordinates of the receptor and source, the plume centerline height, source strength, wind velocity, dispersion coefficients, atmospheric temperature, and atmospheric pressure.…”

Dispersion coefficients for coastal regions

“…The final data set selected for this analysis was obtained from field measurement programs conducted in northern Norway near Bardufoss during the summer of 1968. These tests, as described by Eidsvik, et al, (1972) and Gotaas (1975) and summarized by Minott, et al, (1977), were originally conducted to define dispersion characteristics in the channeled flows of deep valleys. A comparison of over-land to over-water dispersion was also presented by the authors.…”

“…The vertical dispersion coefficients extracted from the Norway (Eidsvik, et al, 1972 andGotaas, 1975) and the Shoreline (Smith, et al, 1969) tests were summarized by Minott, et al (1977) and are presented in Figures 3. 7 and 3.8, respectively. There are obvious limitations upon the use of these data.…”