Scavenging model for stratified precipitation
The purpose of the model described in this paper is to provide an enhanced capability of simulating precipitation scavening of pollutant particles by stratified precipitation for numerical models of medium- to long-range transport, diffusion and deposition. The long-range transport model (2BPUFF) is a two-dimensional axisymmetric Lagrangian model using scale-dependent diffusion with transport along a trajectory deduced from measured winds. The medium-range transport model is an adaptation of a three-dimensional particle-in-cell code (ADPIC) which uses measured winds that have been interpolated mass-consistently to a grid. Both of these models currently have crude capabilities to include precipitation scavenging. As the pollutant cloud moves downwind, it can pass through regions of precipitation where pollutant particles are removed at a rate, lambda, which depends directly on a specified precipitation rate, and are deposited on the ground immediately; therefore the pollutant concentration decreases in areas of precipitation as exp(-lambda t). The major deficiencies of the existing model are the necessity of specifying the rain rate directly, the lack of consideration of vertical variations of hydrometeor concentrations and removal rates, and the effects on scavenging rate of the various microphysical mechanisms. While developing a new model that reduces these deficiencies, it is necessary to remain consistent in complexity and detail with the assumptions used in the transport and diffusion models.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6609670
- Report Number(s):
- UCRL-87551; CONF-821136-1; ON: DE83003374
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Atmospheric-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
ATMOSPHERIC CHEMISTRY
ATMOSPHERIC PRECIPITATIONS
CHEMISTRY
CLOUDS
CONDENSATION NUCLEI
DIFFUSION
ENVIRONMENTAL TRANSPORT
MASS TRANSFER
MATHEMATICAL MODELS
PARTICLES
PARTICULATES
POLLUTION
PRECIPITATION SCAVENGING
RAIN
SEPARATION PROCESSES
SNOW
THREE-DIMENSIONAL CALCULATIONS