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dc.contributor.authorWolfe, G. M.
dc.contributor.authorThornton, J. A.
dc.contributor.authorYatavelli, R. L. N.
dc.contributor.authorMcKay, M.
dc.contributor.authorGoldstein, A. H.
dc.contributor.authorLaFranchi, B.
dc.contributor.authorMin, K.-E.
dc.contributor.authorCohen, R.C.
dc.date.accessioned2020-09-16T17:05:13Z
dc.date.available2020-09-16T17:05:13Z
dc.date.issued2009-01-27
dc.description.abstractDuring the Biosphere Effects on AeRosols and Photochemistry EXperiment 2007 (BEARPEX-2007), we observed eddy covariance (EC) fluxes of speciated acyl peroxy nitrates (APNs), including peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN) and peroxymethacryloyl nitrate (MPAN), above a Ponderosa pine forest in the western Sierra Nevada. All APN fluxes are net downward during the day, with a median midday PAN exchange velocity of −0.3 cm s⁻¹; nighttime storage-corrected APN EC fluxes are smaller than daytime fluxes but still downward. Analysis with a standard resistance model shows that loss of PAN to the canopy is not controlled by turbulent or molecular diffusion. Stomatal uptake can account for 25 to 50% of the observed downward PAN flux. Vertical gradients in the PAN thermal decomposition (TD) rate explain a similar fraction of the flux, suggesting that a significant portion of the PAN flux into the forest results from chemical processes in the canopy. The remaining "unidentified" portion of the net PAN flux (~15%) is ascribed to deposition or reactive uptake on non-stomatal surfaces (e.g. leaf cuticles or soil). Shifts in temperature, moisture and ecosystem activity during the summer – fall transition alter the relative contribution of stomatal uptake, non-stomatal uptake and thermochemical gradients to the net PAN flux. Daytime PAN and MPAN exchange velocities are a factor of 3 smaller than those of PPN during the first two weeks of the measurement period, consistent with strong intra-canopy chemical production of PAN and MPAN during this period. Depositional loss of APNs can be 3–21% of the gross gas-phase TD loss depending on temperature. As a source of nitrogen to the biosphere, PAN deposition represents approximately 4–19% of that due to dry deposition of nitric acid at this site.en_US
dc.description.sponsorshipThe authors thank J. Mao, Z. Chen, X. Ren and B. Brune for providing HOx measurements, J. Gilman and J. de Gouw for VOC measurements, J. Crounse and P. Wennberg for HNO3 flux data and permeation tube designs, and D. Farmer and I. Faloona for their comments on the manuscript and helpful discussion on eddy covariance and spectral analysis. We also thank P. Wooldridge for help with sonic anemometer measurements, J. Roberts, F. Flocke, E. Fischer, D. Reidmiller and D. Jaffe for assistance with instrument calibration, BFRS staff for their logistical expertise and Sierra Pacific Industries for providing the property to conduct this research. This work was largely supported by a National Science Foundation grant ATM-0633897. G. Wolfe acknowledges support from NASA Earth Systems Science Fellowship NNG-05GP64H.en_US
dc.description.urihttps://acp.copernicus.org/articles/9/615/2009/en_US
dc.format.extent20 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2pwhh-gn2v
dc.identifier.citationWolfe, G. M., Thornton, J. A., Yatavelli, R. L. N., McKay, M., Goldstein, A. H., LaFranchi, B., Min, K.-E., and Cohen, R. C.: Eddy covariance fluxes of acyl peroxy nitrates (PAN, PPN and MPAN) above a Ponderosa pine forest, Atmos. Chem. Phys., 9, 615–634, https://doi.org/10.5194/acp-9-615-2009, 2009.en_US
dc.identifier.urihttps://doi.org/10.5194/acp-9-615-2009
dc.identifier.urihttp://hdl.handle.net/11603/19661
dc.language.isoen_USen_US
dc.publisherCopernicusen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Joint Center for Earth Systems Technology
dc.relation.ispartofUMBC Physics Department
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rightsAttribution 3.0 Unported*
dc.rights.urihttps://creativecommons.org/licenses/by/3.0/*
dc.titleEddy covariance fluxes of acyl peroxy nitrates (PAN, PPN and MPAN) above a Ponderosa pine foresten_US
dc.typeTexten_US


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This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
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