and velocity deficit. In general, these building induced effects act to restrict the rise that the

plume would have in the absence of the building.

PRIME was originally designed (Schulman et al., 2000) to enhance plume growth using

Pasquill Gifford (PG) dispersion (Pasquill 1961; Gifford 1961). AERMOD’s estimate of plume

growth is based on dispersion parameters derived from profiles of turbulence (see Section 4), not

from radiation base turbulence surrogates as is done in the PG approach. A basic design tenet for

incorporating PRIME into AERMOD was to be as faithful as possible to the PRIME formulation

while ensuring that 1) AERMOD’s ambient dispersion was used in place of PG dispersion and 2)

far beyond the wake region, where building influences should be insignificant, concentrations

approach the AERMOD estimate. Therefore, within the wake, PRIME algorithms are use

exclusively to calculate concentration with AERMOD-derived ambient turbulent intensities as

input. To insure a smooth transition between concentrations estimated by PRIME, within the

wake, and AERMOD estimates in the far field, concentrations beyond the wake are estimated as

the weighted sum of the two calculations. That is, beyond the wake the total concentration (

Ctotal)is calculated as follows:

where

Cprimeis the concentration estimated using the PRIME algorithms with AERMOD-derivedmeteorological inputs,

CAERMODis the concentration estimated using AERMOD withoutconsidering building wake effects, and ( the weighting parameter. The weighting parameter, (, is

designed such that the contribution from the PRIME calculation decreases exponentially with

vertical, lateral and downwind distance from the wake. It is calculated as follows:

where

xis the downwind distance from the upwind edge of the building to the receptor,yis thelateral (crosswind) distance from the building centerline to the receptor,

zis the receptor heightabove ground, F

xgis longitudinal dimension of the wake, Fygis the distance from the buildingcenterline to lateral edge of the wake, and F

zgis the height of the wake at the receptor location.5.6

Plume RiseCalculations in AERMOD5.6.1 PLUME RISE IN THE CBL

The plume rise for the direct source is given by the superposition of source momentum and

buoyancy effects following Briggs (1984).

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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