5.2.1 DIRECT SOURCE CONTRIBUTION TO CONCENTRATION CALCULATIONS IN

THE CBL

Following Weil et al. (1997), the concentration due to the direct plume is given by:

uis the wind speed at stack top,Fyis the lateral distribution function withmeander (discussed in Section 5.4),

w a w(ajis defined below in eq.(62) , )hdis the directj j= *source plume rise calculated from eq. (91), and

z=zrandzpin the horizontal and terrainfollowingstates, respectively. Here, Q

djand Fzjare the effective source height and verticaldispersion parameter corresponding to each of the two distributions in eq. (53). The subscript

jisequal to 1 for updrafts and 2 for downdrafts. The lateral and vertical dispersion parameters ( F

yandF

zj), resulting from the combined effects of ambient, buoyancy-induced, and building-inducedturbulence are calculated as discussed in Sections 5.5.1.1 and 5.5.1.2 respectively. Here, F

zj(with

j= 1 or 2) is the vertical dispersion parameter corresponding to each of the Gaussian distributionsused in the bi-Gaussian pdf, (see Section 5.5.1.2) and 8

j, the weighting coefficient for eachdistribution in eq.(53), is calculated from Weil et al. (1997) as

Recall that is the total effective vertical turbulence and is calculated from eq. (34). The ~σ

wT

parameters appearing in eq.(62) are given by

and

Ris assumed to be 2.0 (Weil et al., 1997). Likewise, the termw x uin eq. (60) followsjfrom the

Fzderivation and thew&jappearing in the bi-Gaussian form (see discussion of eq. (53)) .The lateral dispersion parameter ( F

y,) is calculated from eq. (75) (Weil et al., 1997).In eq. (59), an image plume is used to satisfy the no-flux condition at the ground, i.e., an

image plume from a source at

z = -hs, which results in the exponential terms containingz +Qdjonthe right-hand side of eq. (59). This image source results in a positive flux of material at

z = zi,and additional image sources are introduced at

z =2zi + hs, -2zi - hs, 4zi + hs, -4zi - hs, etc. tosatisfy all the subsequent no-flux conditions occurring at

z= 0 andzi.

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castellano: DISPER CUSTIC DESCAR RADIA italiano:

castellano: DIS CUS DES RAD english: DIS CUS DES RAD

português: DIS CUS DES RAD italiano: DIS CUS DES RAD