Dispersion of Heavy Particles Emitted from Area Sources in the Unstable Atmospheric Boundary Layer

Ying Pan, Marcelo Chamecki, Scott A. Isard

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Reliable predictions of the daytime dispersal of heavy particles in the unstable atmospheric boundary layer are important in a variety of disciplines. For many applications, particles disperse from area sources near the ground, and corresponding theoretical solutions are desired to reveal insight into the physical processes. Here, theoretical solutions recently developed for neutral conditions are modified to include the effects of atmospheric instability. The Obukhov length LO and convection velocity w{star operator} are introduced to characterize the patterns of particle dispersion, in additional to friction velocity u{star operator} and settling velocity ws used in the neutral case. The major effects of atmospheric instability are accounted for by modifying the vertical velocity variance profile and considering the ratio of velocity scales w{star operator}/u{star operator}. Theoretical predictions including the mean concentration profile, plume height, and horizontal transport above the source, and ground deposition flux downwind from the source agree well with large-eddy simulation results while the particle plume is within the atmospheric surface layer. The deposition curve is characterized by a power-law decay whose exponent depends on u{star operator}, ws, and w{star operator}. A second steeper power-law develops once the plume extends into the mixed layer. This effect is enhanced with increasing atmospheric instability, implying that particles disperse farther from the source.

Original languageEnglish (US)
Pages (from-to)235-256
Number of pages22
JournalBoundary-Layer Meteorology
Issue number2
StatePublished - Feb 2013

All Science Journal Classification (ASJC) codes

  • Atmospheric Science


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