Air-Parcel Residence Times Within Forest Canopies

dc.contributor.authorGerken, Tobias
dc.contributor.authorChamecki, Marcelo
dc.contributor.authorFuentes, Jose D.
dc.date.accessioned2017-12-20T21:47:36Z
dc.date.available2017-12-20T21:47:36Z
dc.date.issued2017-06
dc.description.abstractWe present a theoretical model, based on a simple model of turbulent diffusion and first-order chemical kinetics, to determine air-parcel residence times and the out-of-canopy export of reactive gases emitted within forest canopies under neutral conditions. Theoretical predictions of the air-parcel residence time are compared to values derived from large-eddy simulation for a range of canopy architectures and turbulence levels under neutral stratification. Median air-parcel residence times range from a few sec in the upper canopy to approximately 30 min near the ground and the distribution of residence times is skewed towards longer times in the lower canopy. While the predicted probability density functions from the theoretical model and large-eddy simulation are in good agreement with each other, the theoretical model requires only information on canopy height and eddy diffusivities inside the canopy. The eddy-diffusivity model developed additionally requires the friction velocity at canopy top and a parametrized profile of the standard deviation of vertical velocity. The theoretical model of air-parcel residence times is extended to include first-order chemical reactions over a range of of Damköhler numbers (Da) characteristic of plant-emitted hydrocarbons. The resulting out-of-canopy export fractions range from near 1 for Da=10−3Da=10−3 to less than 0.3 at Da=10Da=10. These results highlight the necessity for dense and tall forests to include the impacts of air-parcel residence times when calculating the out-of-canopy export fraction for reactive trace gases.en_US
dc.identifier.citationGerken, Tobias, Marcelo Chamecki, and Jose D. Fuentes. "Air-Parcel Residence Times Within Forest Canopies." Boundary Layer Meteorology (June 2017): 1-26. DOI:https://dx.doi.org/10.1007/s10546-017-0269-7.en_US
dc.identifier.issn0006-8314
dc.identifier.urihttps://scholarworks.montana.edu/handle/1/14098
dc.titleAir-Parcel Residence Times Within Forest Canopiesen_US
mus.citation.extentfirstpage1en_US
mus.citation.extentlastpage26en_US
mus.citation.journaltitleBoundary Layer Meteorologyen_US
mus.contributor.orcidGerken, Tobias|0000-0001-5617-186Xen_US
mus.data.thumbpage4en_US
mus.identifier.categoryLife Sciences & Earth Sciencesen_US
mus.identifier.doi10.1007/s10546-017-0269-7en_US
mus.relation.collegeCollege of Agricultureen_US
mus.relation.departmentLand Resources & Environmental Sciences.en_US
mus.relation.universityMontana State University - Bozemanen_US

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