In-canopy gas-phase chemistry during CABINEX 2009: sensitivity of a 1-D canopy model to vertical mixing and isoprene chemistry

Bryan, A. M.; Bertman, S. B.; Carroll, Mary Anne; Dusanter, Sébastien; Edwards, George C.; Forkel, R.; Griffith, Stephen M.; Guenther, Alex; Hansen, R. F.; Helmig, Detlev; Jobson, T.; Keutsch, Frank N.; Lefer, B. L.; Pressley, S. N.; Shepson, P. B.; Stevens, P. S.; Steiner, Allison L.

doi:10.5194/acp-12-8829-2012

Cited by 84 publications

(75 citation statements)

References 87 publications

(122 reference statements)

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“…In addition, the ratios of MVK + MACR, major isoprene oxidation products and isoprene at this period, are significantly lower than those of late morning to early afternoon. The enhanced isoprene levels in the late afternoon or early evening have been also reported in previous studies (Apel et al, 2002;Bryan et al, 2012). The branch enclosure observations demonstrate that isoprene is not emitted from the pine plantation but rather transported from surrounding broadleaf forests, because right outside of the pine plantation (200 m × 200 m) is a forested area dominated by oak trees.…”

Section: Observational Resultssupporting

confidence: 54%

“…The temporal variation of MT is affected by the planetary boundary layer evolution, with a pattern of higher MT levels during night than those of midday as has been often reported in other forest environments (Bryan et al, 2012;Kim et al, 2010). This can be explained by interplays between boundary layer evolution and temperature-dependent MT emission.…”

Section: Observational Resultsmentioning

confidence: 83%

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Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

Kim

Lee³

et al. 2015

Atmos. Chem. Phys.

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Abstract. Rapid urbanization and economic development in East Asia in past decades has led to photochemical air pollution problems such as excess photochemical ozone and aerosol formation. Asian megacities such as Seoul, Tokyo, Shanghai, Guangzhou, and Beijing are surrounded by densely forested areas, and recent research has consistently demonstrated the importance of biogenic volatile organic compounds (VOCs) from vegetation in determining oxidation capacity in the suburban Asian megacity regions. Uncertainties in constraining tropospheric oxidation capacity, dominated by hydroxyl radical, undermine our ability to assess regional photochemical air pollution problems. We present an observational data set of CO, NO x , SO 2 , ozone, HONO, and VOCs (anthropogenic and biogenic) from Taehwa research forest (TRF) near the Seoul metropolitan area in early June 2012. The data show that TRF is influenced both by aged pollution and fresh biogenic volatile organic compound emissions. With the data set, we diagnose HO x (OH, HO 2 , and RO 2 ) distributions calculated using the University of Washington chemical box model (UWCM v2.1) with nearexplicit VOC oxidation mechanisms from MCM v3.2 (Master Chemical Mechanism). Uncertainty from unconstrained HONO sources and radical recycling processes highlighted in recent studies is examined using multiple model simulations with different model constraints. The results suggest that (1) different model simulation scenarios cause systematic differences in HO x distributions, especially OH levels (up to 2.5 times), and (2) radical destruction (HO 2 + HO 2 or HO 2 + RO 2 ) could be more efficient than radical recycling (RO 2 + NO), especially in the afternoon. Implications of the uncertainties in radical chemistry are discussed with respect to ozone-VOC-NO x sensitivity and VOC oxidation product formation rates. Overall, the NO x limited regime is assessed except for the morning hours (8 a.m. to 12 p.m. local standard time), but the degree of sensitivity can significantly vary depending on the model scenarios. The model results also suggest that RO 2 levels are positively correlated with oxygenated VOCs (OVOCs) production that is not routinely constrained by observations. These unconstrained OVOCs can cause higher-than-expected OH loss rates (missing OH reactivity) and secondary organic aerosol formation. The series of modeling experiments constrained by observations strongly urge observational constraint of the radical pool to enable precise understanding of regional photochemical pollution problems in the East Asian megacity region.

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Section: Observational Resultssupporting

confidence: 54%

Section: Observational Resultsmentioning

confidence: 83%

Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

Kim

Lee³

et al. 2015

Atmos. Chem. Phys.

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“…The results presented here provide an example of how these techniques can be applied to explain mixing within the forest canopy, a key element for understanding atmospheric chemical gradients within and above forest canopies. The implications of this increased vertical mixing on atmospheric chemistry are explored in a separate paper in this Special Issue (Bryan et al, 2011), which will incorporate the impacts of vertical mixing on modeled gradients of atmospheric constituents.…”

Section: Discussionmentioning

confidence: 99%

Analysis of coherent structures and atmosphere-canopy coupling strength during the CABINEX field campaign

et al. 2011

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Abstract. Intermittent coherent structures can be responsible for a large fraction of the exchange between a forest canopy and the atmosphere. Quantifying their contribution to momentum and heat fluxes is necessary to interpret measurements of trace gases and aerosols within and above forest canopies. The primary objective of the Community Atmosphere-Biosphere Interactions Experiment (CABINEX) field campaign (10 July 2009 to 9 August 2009) was to study the chemistry of volatile organic compounds (VOC) within and above a forest canopy. In this manuscript we provide an analysis of coherent structures and canopy-atmosphere exchange during CABINEX to support in-canopy gradient measurements of VOC. We quantify the number and duration of coherent structure events and their percent contribution to momentum and heat fluxes with two methods: (1) quadrant-hole analysis, and (2) wavelet analysis. Despite differences in the duration and number of events, both methods predict that coherent structures contribute 40-50 % to momentum fluxes and 44-65 % to heat fluxes during the CABINEX campaign. Contributions associated with coherent structures are slightly greater under stable atmospheric conditions. By comparing heat fluxes within and above the canopy, we determine the degree of coupling between upper canopy and atmosphere, and find that they are coupled the majority of the time. Uncoupled canopyatmosphere events occur in the early morning (4-8 a.m. local time) approximately 30 % of the time. This study conCorrespondence to: A. L. Steiner (alsteiner@umich.edu) firms that coherent structures contribute significantly to the exchange of heat and momentum between the canopy and atmosphere at the CABINEX site, and indicates the need to include these transport processes when studying the mixing and chemical reactions of trace gases and aerosols between a forest canopy and the atmosphere.

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“…This reactivity will be referred to as the concentration-normalized reactivity of the BVOC emission profile. The total mixing ratio value of 1 ppbV was selected as a reasonable approximation of summertime afternoon monoterpene mixing ratios in the canopy of a forest environment (Bryan et al, 2012;Nölscher et al, 2012). The compounds used in the reactivity calculations and their corresponding OH and O 3 rate constants are presented in Table 3.…”

Section: Calculating Atmospheric Reactivity Of Bvoc Emissionsmentioning

confidence: 99%

Impacts of simulated herbivory on volatile organic compound emission profiles from coniferous plants

2015

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Abstract. The largest global source of volatile organic compounds (VOCs) in the atmosphere is from biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. This study investigated the effects of one global change stressor, increased herbivory, on plant emissions from five different coniferous species: bristlecone pine (Pinus aristata), blue spruce (Picea pungens), western redcedar (Thuja plicata), grand fir (Abies grandis), and Douglas-fir (Pseudotsuga menziesii). Herbivory was simulated in the laboratory via exogenous application of methyl jasmonate (MeJA), a herbivory proxy. Gas-phase species were measured continuously with a gas chromatograph coupled to a mass spectrometer and flame ionization detector (GC-MS-FID). Stress responses varied between the different plant types and even between experiments using the same set of saplings. The compounds most frequently impacted by the stress treatment were alpha-pinene, beta-pinene, 1,8-cineol, beta-myrcene, terpinolene, limonene, and the cymene isomers. Individual compounds within a single experiment often exhibited a different response to the treatment from one another.

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In-canopy gas-phase chemistry during CABINEX 2009: sensitivity of a 1-D canopy model to vertical mixing and isoprene chemistry

Cited by 84 publications

References 87 publications

Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

Analysis of coherent structures and atmosphere-canopy coupling strength during the CABINEX field campaign

Impacts of simulated herbivory on volatile organic compound emission profiles from coniferous plants

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