The Chemistry of Atmosphere-Forest Exchange (CAFE) Model – Part 2: Application to BEARPEX-2007 observations

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dc.contributor.authorWolfe, Glenn
dc.contributor.authorThornton, J. A.
dc.contributor.authorBouvier-Brown, N. C.
dc.contributor.authorGoldstein, A. H.
dc.contributor.authorPark, J. H.
dc.contributor.authorMcKay, M.
dc.contributor.authorMatross, D. M.
dc.contributor.authorMao, J.
dc.contributor.authorBrune, W. H.
dc.contributor.authorLaFranchi, B. W.
dc.contributor.authorBrowne, E. C.
dc.contributor.authorMin, K.E.
dc.contributor.authorWooldridge, P. J.
dc.contributor.authorCohen, R. C.
dc.contributor.authorCrounse, J.D.
dc.contributor.authorFaloona, I. C.
dc.contributor.authorGilman, J. B.
dc.contributor.authorKuster, W. C.
dc.contributor.authorGouw, J. A. de
dc.contributor.authorHuisman, A.
dc.contributor.authorKeutsch, F. N.
dc.date.accessioned2020-09-16T17:56:00Z
dc.date.available2020-09-16T17:56:00Z
dc.date.issued2011-02-15
dc.description.abstractIn a companion paper, we introduced the Chemistry of Atmosphere-Forest Exchange (CAFE) model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. Here, we apply CAFE to noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007). In this work we evaluate the CAFE modeling approach, demonstrate the significance of in-canopy chemistry for forest-atmosphere exchange and identify key shortcomings in the current understanding of intra-canopy processes. CAFE generally reproduces BEARPEX-2007 observations but requires an enhanced radical recycling mechanism to overcome a factor of 6 underestimate of hydroxyl (OH) concentrations observed during a warm (~29 °C) period. Modeled fluxes of acyl peroxy nitrates (APN) are quite sensitive to gradients in chemical production and loss, demonstrating that chemistry may perturb forest-atmosphere exchange even when the chemical timescale is long relative to the canopy mixing timescale. The model underestimates peroxy acetyl nitrate (PAN) fluxes by 50% and the exchange velocity by nearly a factor of three under warmer conditions, suggesting that near-surface APN sinks are underestimated relative to the sources. Nitric acid typically dominates gross dry N deposition at this site, though other reactive nitrogen (NOy) species can comprise up to 28% of the N deposition budget under cooler conditions. Upward NO2 fluxes cause the net above-canopy NOy flux to be ~30% lower than the gross depositional flux. CAFE under-predicts ozone fluxes and exchange velocities by ~20%. Large uncertainty in the parameterization of cuticular and ground deposition precludes conclusive attribution of non-stomatal fluxes to chemistry or surface uptake. Model-measurement comparisons of vertical concentration gradients for several emitted species suggests that the lower canopy airspace may be only weakly coupled with the upper canopy. Future efforts to model forest-atmosphere exchange will require a more mechanistic understanding of non-stomatal deposition and a more thorough characterization of in-canopy mixing processes.en_US
dc.description.sponsorshipThe authors acknowledge support from a National Science Foundation grant ATM-0633897. GMW was partially supported by a U.S.-EPA STAR Fellowship Assistance under Agreement No. FP-91698901. This work has not been formally reviewed by EPA. The views expressed in this work are solely those of the authors; EPA and NSF do not endorse any products or commercial services mentioned. The authors also thank F. Paulot for helpful discussions on isoprene oxidation, S. Fares for his insights on ozone fluxes and L. Ganzeveld, T. Karl and an anonymous referee for their critical feedback on both the model and the manuscripten_US
dc.description.urihttps://acp.copernicus.org/articles/11/1269/2011/en_US
dc.format.extent26 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m20aqv-mvnv
dc.identifier.citationWolfe, G. M., Thornton, J. A., Bouvier-Brown, N. C., Goldstein, A. H., Park, J.-H., McKay, M., Matross, D. M., Mao, J., Brune, W. H., LaFranchi, B. W., Browne, E. C., Min, K.-E., Wooldridge, P. J., Cohen, R. C., Crounse, J. D., Faloona, I. C., Gilman, J. B., Kuster, W. C., de Gouw, J. A., Huisman, A., and Keutsch, F. N.: The Chemistry of Atmosphere-Forest Exchange (CAFE) Model – Part 2: Application to BEARPEX-2007 observations, Atmos. Chem. Phys., 11, 1269–1294, https://doi.org/10.5194/acp-11-1269-2011, 2011.en_US
dc.identifier.urihttps://doi.org/10.5194/acp-11-1269-2011
dc.identifier.urihttp://hdl.handle.net/11603/19665
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.rightsPublic Domain Mark 1.0*
dc.rightsThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
dc.rights.urihttp://creativecommons.org/publicdomain/mark/1.0/*
dc.titleThe Chemistry of Atmosphere-Forest Exchange (CAFE) Model – Part 2: Application to BEARPEX-2007 observationsen_US
dc.typeTexten_US

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