The depletion options (DRYDPLT and WETDPLT) may be used with CONC, DEPOS, DDEP or WDEP, but particle information must be specified in the SO pathway (see Section 3.3.6) if DRYDPLT is included, and scavenging coefficients must be specified on the SO pathway if WETDPLT is included. When particles are modeled, a settling velocity and a deposition velocity are calculated for each size category. The settling velocity causes the plume to "tilt" towards the surface (if the plume is elevated) as it travels downwind, while the deposition velocity is used to calculate the flux of matter deposited at the surface. If the depletion parameters (DRYDPLT and WETDPLT) are not included as model options, then the mass of particles deposited on the surface from gravitational settling and/or precipitation scavenging is not removed from the plume. However, plume settling is still modeled if particle information is included on the SO pathway, and wet deposition is still modeled if scavenging coefficients are included on the SO pathway. The no depletion option may be acceptable if deposition is weak, and it will result in an overestimate of both concentrations and deposition. When DRYDPLT and/or WETDPLT are included, particle mass is removed from the plume as it is deposited on the surface, thereby conserving mass. However, the additional calculations required for dry depletion corrections will result in significantly longer execution times for the model, since the model must integrate along the plume path between the source and receptor. The amount of increase in execution time will vary depending on source characteristics and the terrain grid option used, but could be a factor of 10 or more for typical applications.
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APLICACIONES castellano: DIS CUS DES RAD english: DIS CUS DES RAD
português: DIS CUS DES RAD italiano: DIS CUS DES RAD
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