Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR

Karl, Matthias; Dorn, Hans-Peter; Holland, F.; Koppmann, R.; Poppe, D.; Rupp, L.; Schaub, A.; Wahner, Andreas

doi:10.1007/s10874-006-9034-x

Cited by 105 publications

(86 citation statements)

References 40 publications

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“…The chemical mechanism employed in the model was RACM2 (Stockwell et al, 1997;Goliff et al, 2013), with implementation of the Mainz Isoprene Mechanism (MIM; Pöschl et al, 2000) and update versions by Geiger et al (2003) and Karl et al (2006) for isoprene reactions. The model was constrained by measured photolysis frequencies, ancillary meteorology and inorganic gas measurements, as well as VOC data.…”

Section: Box Modelmentioning

confidence: 99%

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

et al. 2017

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Abstract. Total OH reactivity measurements were conducted on the Peking University campus (Beijing) in August 2013 and in Heshan (Guangdong province) from October to November 2014. The daily median OH reactivity was 20 ± 11 s −1 in Beijing and 31 ± 20 s −1 in Heshan, respectively. The data in Beijing showed a distinct diurnal pattern with the maxima over 27 s −1 in the early morning and minima below 16 s −1 in the afternoon. The diurnal pattern in Heshan was not as evident as in Beijing. Missing reactivity, defined as the difference between measured and calculated OH reactivity, was observed at both sites, with 21 % missing reactivity in Beijing and 32 % missing reactivity in Heshan. Unmeasured primary species, such as branched alkenes, could contribute to missing reactivity in Beijing, especially during morning rush hours. An observation-based model with the RACM2 (Regional Atmospheric Chemical Mechanism version 2) was used to understand the daytime missing reactivity in Beijing by adding unmeasured oxygenated volatile organic compounds and simulated intermediates of the degradation from primary volatile organic compounds (VOCs). However, the model could not find a convincing explanation for the missing reactivity in Heshan, where the ambient air was found to be more aged, and the missing reactivity was presumably attributed to oxidized species, such as unmeasured aldehydes, acids and dicarbonyls. The ozone production efficiency was 21 % higher in Beijing and 30 % higher in Heshan when the model was constrained by the measured reactivity, compared to the calculations with measured and modeled species included, indicating the importance of quantifying the OH reactivity for better understanding ozone chemistry.

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Section: Box Modelmentioning

confidence: 99%

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

et al. 2017

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“…The uncertainty range for this crucial (averaged) rate is estimated by Peeters and Müller (2010) to be between 0.3 and 1.3 times this adopted value, based on two independent experimental constraints: the observed yield of MVK and MACR in the OH-initiated isoprene oxidation experiments of Karl et al (2006) conducted at moderate NO levels, and the peroxy radical budget in the experiments of Paulot et al (2009b). In addition, Archibald et al (2010) concluded from box model simulations of the experiments by Paulot et al (2009b) that the 1,6-H shift rates estimated from first principles by Peeters et al (2009) should be both equalised and reduced to some extent in order to match the observations, in particular for the formation rate of hydroperoxides.…”

Section: The Leuven Isoprene Mechanism Lim0 (Peeters Et Al 2009; Pementioning

confidence: 99%

Improved global modelling of HO<sub>x</sub> recycling in isoprene oxidation: evaluation against the GABRIEL and INTEX-A aircraft campaign measurements

2010

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Abstract. Stimulated by recent important developments regarding the oxidation chemistry of isoprene, this study evaluates and quantifies the impacts of different mechanism updates on the boundary layer concentrations of OH and HO 2 radicals using the IMAGESv2 global chemistry transport model. The model results for HO x , isoprene, NO, and ozone are evaluated against air-based observations from the GABRIEL campaign, conducted over the Guyanas in October 2005, and from the INTEX-A campaign over the Eastern US in summer 2004. The version 2 of the Mainz Isoprene Mechanism (MIM2, Taraborrelli et al., 2009) used as reference mechanism in our simulations, has been modified to test (i) the artificial OH recycling proposed by , (ii) the epoxide formation mechanism proposed by Paulot et al. (2009b), and finally (iii) the HO x regeneration of the Leuven Isoprene Mechanism (LIM0) proposed by Peeters et al. (2009);Peeters and Müller (2010). The simulations show that the LIM0 scheme holds by far the largest potential impact on HO x concentrations over densely vegetated areas in the Tropics as well as at mid-latitudes. Strong increases, by up to a factor of 4 in the modelled OH concentrations, and by a factor of 2.5-3 in the HO 2 abundances are estimated through the LIM0 mechanism compared to the traditional isoprene degradation schemes. Comparatively much smaller OH increases (<25%) are associated with the implementation of the mechanism of Paulot et al. (2009b); moreover, the global production of epoxides is strongly suppressed (by a factor of 4) when the LIM0 scheme is combined Correspondence to: T. Stavrakou (jenny@aeronomie.be) with this mechanism. Hydroperoxy-aldehydes (HPALDs) are found to be major first-generation products in the oxidation of isoprene by OH, with a combined globally averaged yield of 50-60%. The use of the LIM0 chemistry in the global model allows for reconciling the model with the observed concentrations at a satisfactory level, compared to the other tested mechanisms, as the observed averaged mixing ratios of both OH and HO 2 in the boundary layer can be reproduced to within 30%. In spite of the remaining uncertainties in the theoretically-predicted rates of critical radical reactions leading to the formation of HPALDs, and even more in the subsequent degradation of these new compounds, the current findings make a strong case for the newly proposed chemical scheme. Experimental confirmation and quantification is urgently needed for the formation of HPALDs and for their fast OH-generating photolysis.

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“…Isoprene (Isop) is attacked by OH to form isoprene peroxy radical (Isop-O 2 ). Isop-O 2 then reacts with NO to produce Isop-O radical with the yield of 90% (Reaction R2a in Appendix C) and subsequently to produce HCHO, MVK, and MACR (Reactions R5a, b in Appendix C) with a yield of 63%, 35%, and 24%, respectively, in high-NO x conditions (Tuazon and Atkinson, 1990;Paulson et al, 1992;Ruppert and Becker, 2000;Paulot et al, 2009;Miyoshi et al, 1994;Sprengnether et al, 2002;Karl et al, 2006). On the other hand, Isop-O 2 also competitively reacts with RO 2 to produce HCHO, MVK, and MACR with a yield of 34%, 16%, and 20%, respectively, via Isop-O (Reaction R4a in Appendix C) under NO x -free conditions (Ruppert and Becker, 2000;Miyoshi et al, 1994).…”

Section: Appendix C Hcho Production Pathways C1 Hcho Yield From Oh-inmentioning

confidence: 99%

Observations of elevated formaldehyde over a forest canopy suggest missing sources from rapid oxidation of arboreal hydrocarbons

et al. 2010

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Abstract.To better understand the processing of biogenic VOCs (BVOCs) in the pine forests of the US Sierra Nevada, we measured HCHO at Blodgett Research Station using Quantum Cascade Laser Spectroscopy (QCLS) during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) of late summer 2007. Four days of the experiment exhibited particularly copious HCHO, with midday peaks between 15-20 ppbv, while the other days developed delayed maxima between 8-14 ppbv in the early evening. From the expansive photochemical data set, we attempt to explain the observed HCHO concentrations by quantifying the various known photochemical production and loss terms in its chemical budget. Overall, known chemistry predicts a factor of 3-5 times less HCHO than observed. By examining diurnal patterns of the various budget terms we conclude that, during the high HCHO period, local, highly reactive oxidation chemistry produces an abundance of formaldehyde at the site. The results support the hypothesis of previous work at Blodgett Forest suggesting that large quantities of oxidation products, observed directly above the ponderosa pine canopy, Correspondence to: W. Choi (wschoi@ucdavis.edu) are evidence of profuse emissions of very reactive volatile organic compounds (VR-VOCs) from the forest. However, on the majority of days, under generally cooler and more moist conditions, lower levels of HCHO develop primarily influenced by the influx of precursors transported into the region along with the Sacramento plume.

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Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR

Cited by 105 publications

References 40 publications

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

Improved global modelling of HO<sub>x</sub> recycling in isoprene oxidation: evaluation against the GABRIEL and INTEX-A aircraft campaign measurements

Observations of elevated formaldehyde over a forest canopy suggest missing sources from rapid oxidation of arboreal hydrocarbons

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Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR

Cited by 105 publications

References 40 publications

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

Improved global modelling of HO&lt;sub&gt;x&lt;/sub&gt; recycling in isoprene oxidation: evaluation against the GABRIEL and INTEX-A aircraft campaign measurements

Observations of elevated formaldehyde over a forest canopy suggest missing sources from rapid oxidation of arboreal hydrocarbons

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Improved global modelling of HO<sub>x</sub> recycling in isoprene oxidation: evaluation against the GABRIEL and INTEX-A aircraft campaign measurements