An analytical model for dispersion of biological particles emitted from area sources: Inclusion of dispersion in the crosswind direction

Marcelo Chamecki

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7 Citations (Scopus)

Abstract

An analytical model for dispersion of biological particles such as spores and pollens released from finite area sources into the atmospheric boundary layer is proposed. The model is applicable to rectangular fields aligned with the mean wind and accounts for effects of turbulent dispersion in the vertical and crosswind direction, as well as depletion of airborne material due to dry deposition. Predictions for the mean particle concentration above the area source and ground deposition downwind from it are derived and validated against detailed numerical simulations of pollen dispersal using large eddy simulation. Effects of particle settling velocity and area source size and geometry on dispersal patterns are investigated. Results show that along the centerline above the source, effects of crosswind dispersion are negligible (except for very narrow area sources). Ground deposition fluxes downwind from the source are strongly affected by crosswind dispersion. Similarly to area sources infinitely long in the crosswind direction, deposition fluxes far from rectangular sources display a power-law decay with distance. The power-law exponent is larger than the one for infinitely wide fields and depends on the relative importance of gravitational settling and turbulent dispersion in the vertical and crosswind directions, but does not depend on source geometry. However, the distance from the source at which the power-law decay is first observed does depend on source geometry.

Original languageEnglish (US)
Pages (from-to)30-38
Number of pages9
JournalAgricultural and Forest Meteorology
Volume157
DOIs
StatePublished - May 15 2012

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power law
geometry
pollen
deterioration
dry deposition
pollen flow
particle settling
settling velocity
large eddy simulation
spore
spores
boundary layer
particle
prediction
simulation
effect
material
troposphere

All Science Journal Classification (ASJC) codes

  • Forestry
  • Global and Planetary Change
  • Agronomy and Crop Science
  • Atmospheric Science

Cite this

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abstract = "An analytical model for dispersion of biological particles such as spores and pollens released from finite area sources into the atmospheric boundary layer is proposed. The model is applicable to rectangular fields aligned with the mean wind and accounts for effects of turbulent dispersion in the vertical and crosswind direction, as well as depletion of airborne material due to dry deposition. Predictions for the mean particle concentration above the area source and ground deposition downwind from it are derived and validated against detailed numerical simulations of pollen dispersal using large eddy simulation. Effects of particle settling velocity and area source size and geometry on dispersal patterns are investigated. Results show that along the centerline above the source, effects of crosswind dispersion are negligible (except for very narrow area sources). Ground deposition fluxes downwind from the source are strongly affected by crosswind dispersion. Similarly to area sources infinitely long in the crosswind direction, deposition fluxes far from rectangular sources display a power-law decay with distance. The power-law exponent is larger than the one for infinitely wide fields and depends on the relative importance of gravitational settling and turbulent dispersion in the vertical and crosswind directions, but does not depend on source geometry. However, the distance from the source at which the power-law decay is first observed does depend on source geometry.",
author = "Marcelo Chamecki",
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N2 - An analytical model for dispersion of biological particles such as spores and pollens released from finite area sources into the atmospheric boundary layer is proposed. The model is applicable to rectangular fields aligned with the mean wind and accounts for effects of turbulent dispersion in the vertical and crosswind direction, as well as depletion of airborne material due to dry deposition. Predictions for the mean particle concentration above the area source and ground deposition downwind from it are derived and validated against detailed numerical simulations of pollen dispersal using large eddy simulation. Effects of particle settling velocity and area source size and geometry on dispersal patterns are investigated. Results show that along the centerline above the source, effects of crosswind dispersion are negligible (except for very narrow area sources). Ground deposition fluxes downwind from the source are strongly affected by crosswind dispersion. Similarly to area sources infinitely long in the crosswind direction, deposition fluxes far from rectangular sources display a power-law decay with distance. The power-law exponent is larger than the one for infinitely wide fields and depends on the relative importance of gravitational settling and turbulent dispersion in the vertical and crosswind directions, but does not depend on source geometry. However, the distance from the source at which the power-law decay is first observed does depend on source geometry.

AB - An analytical model for dispersion of biological particles such as spores and pollens released from finite area sources into the atmospheric boundary layer is proposed. The model is applicable to rectangular fields aligned with the mean wind and accounts for effects of turbulent dispersion in the vertical and crosswind direction, as well as depletion of airborne material due to dry deposition. Predictions for the mean particle concentration above the area source and ground deposition downwind from it are derived and validated against detailed numerical simulations of pollen dispersal using large eddy simulation. Effects of particle settling velocity and area source size and geometry on dispersal patterns are investigated. Results show that along the centerline above the source, effects of crosswind dispersion are negligible (except for very narrow area sources). Ground deposition fluxes downwind from the source are strongly affected by crosswind dispersion. Similarly to area sources infinitely long in the crosswind direction, deposition fluxes far from rectangular sources display a power-law decay with distance. The power-law exponent is larger than the one for infinitely wide fields and depends on the relative importance of gravitational settling and turbulent dispersion in the vertical and crosswind directions, but does not depend on source geometry. However, the distance from the source at which the power-law decay is first observed does depend on source geometry.

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