where is the non-dimensional distance with u and F

v X( x u z ) given by effective parameters, v i = σ~ / ~

where " = zi /l, and zi is the mixed layer height.

Based on a preliminary comparison of Fya (eq. (77)) with selected stable and convective cases

from the Prairie Grass experiment (Barad 1958) " was found equal to 78 and p equal to 0.3. As

such, " is treated as a fitting parameter. In later comparisons against the full Prairie Grass data

set (Figure 17), eq. (77) tended towards the lower envelope of this widely scattered data (i.e.,

lateral dispersion estimates are on the lower end of the distribution of measurements). However,

the preliminary values of " (= 78) and p (= 0.3) produced good agreement between AERMOD

concentration predictions and observations (Brode 2002). Therefore, these preliminary values

were retained in AERMOD, and eq. (77) applies for the calculation of Fya for all plumes in both

the SBL and CBL.


Figure 17: Lateral spread (Fy) as a function of non-dimensional distance

(O). The data is taken from the Prairie Grass experiment (Barad


The ambient component of the lateral dispersion for the penetrated source, i.e. a source which

has been released below zi, but penetrates above, is calculated using eq. (77) with hes set equal to

hep (the height of the penetrated source). However, for the injected source, i.e. source released

above zi, no substitution is needed since these sources are modeled as a stable source.

To account for the increase in the turbulence length scale and hence the Lagrangian time scale

with release heights greater than that at Prairie Grass, " is scaled as follows:



n951 - n952 - n953 - n954 - n955 - n956 - n957 - n958 - n959 - n960 - n961 - n962 - n963 - n964 - n965 - n966 - n967 - n968 - n969 - n970 - n971 - n972 - n973 - n974 - n975 - n976 - n977 - n978 - n979 - n980 - n881 - n982 - n983 - n984 - n985 - n986 - n987 - n988 - n989 - n990 - n991 - n992 - n993 - n994 - n995 - n996 - n997 - n998 - n999 - n1000


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