TY - JOUR
T1 - Dispersion of Heavy Particles Emitted from Area Sources in the Unstable Atmospheric Boundary Layer
AU - Pan, Ying
AU - Chamecki, Marcelo
AU - Isard, Scott A.
N1 - Funding Information:
Acknowledgements This research is supported by the United States Department of Agriculture (USDA)-National Institute of Food and Agriculture (NIFA)-Plant Biosecurity Program grant 2009-55605-05049 and the National Science Foundation (NSF) grant AGS1005363.
PY - 2013/2
Y1 - 2013/2
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84872775374&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84872775374&partnerID=8YFLogxK
U2 - 10.1007/s10546-012-9753-2
DO - 10.1007/s10546-012-9753-2
M3 - Article
AN - SCOPUS:84872775374
SN - 0006-8314
VL - 146
SP - 235
EP - 256
JO - Boundary-Layer Meteorology
JF - Boundary-Layer Meteorology
IS - 2
ER -