OH reactivity and concentrations of biogenic volatile organic compounds in a  Mediterranean forest of downy oak trees

Zannoni, Nora; Gros, Valérie; Lanza, Matteo; Sarda, R.; Bonsang, B.; Kalogridis, Cerise; Preunkert, Susanne; Legrand, Michel; Jambert, Corinne; Boissard, Christophe; Lathière, Juliette

doi:10.5194/acp-16-1619-2016

Cited by 42 publications

(45 citation statements)

References 68 publications

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“…Specifically, the correction for the deviation from the pseudo first-order conditions was determined from laboratory and field tests using certified concentration of gas standards containing propane and isoprene. The same procedure was applied in a previous field campaign in an isoprene-dominated environment (Zannoni et al, 2016). Previous field deployments of the same instrument were conducted in environments with low NO x concentrations, for which a correction for OH recycling by NO was not needed.…”

Section: Lsce Crm Instrumentmentioning

confidence: 99%

“…However, the agreement between measured and calculated reactivity is also a valuable result, because it indicates that all trace gases that are relevant for the photochemistry were measured. This was the case in environments that were influenced by anthropogenic OH reactants as in New York and in the North China Plain (Fuchs et al, 2016), in isoprene-dominated environments during daytime in a Mediterranean forest (Zannoni et al, 2016) and in a chamber study (Nölscher et al, 2014). In addition, the gap between measured and calculated OH reactivity could be closed in some field studies if oxygenated VOCs (volatile organic compounds) derived from model calculation were additionally taken into account (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of OH reactivity measurements in the atmospheric simulation chamber SAPHIR

Fuchs¹,

Novelli²,

Rolletter³

et al. 2017

Atmos. Meas. Tech.

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Abstract. Hydroxyl (OH) radical reactivity (k OH ) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in the field, two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016. Chemical conditions were chosen either to be representative of the atmosphere or to test potential limitations of instruments. All types of instruments that are currently used for atmospheric measurements were used in one of the two campaigns. The results of these campaigns demonstrate that OH reactivity can be accurately measured for a wide range of atmospherically relevant chemical conditions (e.g. water vapour, nitrogen oxides, various organic compounds) by all instruments. The precision of the measurements (limit of detection < 1 s −1 at a time resolution of 30 s to a few minutes) is higher for instruments directly detecting hydroxyl radicals, whereas the indirect comparative reactivPublished by Copernicus Publications on behalf of the European Geosciences Union. H. Fuchs et al.: OH reactivity comparison in SAPHIRity method (CRM) has a higher limit of detection of 2 s −1 at a time resolution of 10 to 15 min. The performances of the instruments were systematically tested by stepwise increasing, for example, the concentrations of carbon monoxide (CO), water vapour or nitric oxide (NO). In further experiments, mixtures of organic reactants were injected into the chamber to simulate urban and forested environments. Overall, the results show that the instruments are capable of measuring OH reactivity in the presence of CO, alkanes, alkenes and aromatic compounds. The transmission efficiency in Teflon inlet lines could have introduced systematic errors in measurements for low-volatile organic compounds in some instruments. CRM instruments exhibited a larger scatter in the data compared to the other instruments. The largest differences to reference measurements or to calculated reactivity were observed by CRM instruments in the presence of terpenes and oxygenated organic compounds (mixing ratio of OH reactants were up to 10 ppbv). In some of these experiments, only a small fraction of the reactivity is detected. The accuracy of CRM measurements is most likely limited by the corrections that need to be applied to account for known effects of, for example, deviations from pseudo first-order conditions, nitrogen oxides or water vapour on the measurement. Methods used to derive these corrections vary among the different CRM instruments. Measurements taken with a flowtube instrument combined with the direct detection of OH by chemical ionisation mass spectrometry (CIMS) show limitations in cases of high reactivity and high NO concentrations but were accurate for low reactivity (< 15 s −1 ) and low NO (< 5 ppbv) conditions.

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Section: Lsce Crm Instrumentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of OH reactivity measurements in the atmospheric simulation chamber SAPHIR

Fuchs¹,

Novelli²,

Rolletter³

et al. 2017

Atmos. Meas. Tech.

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“…The advent of airborne measurements of OH reactivity (OHR) provides a method to evaluate the total sink of OH across a range of altitudes and a variety of locations and chemical environments (Mao et al, 2009). Previous work compared surface observations of OHR at a single site to the sum of individually calculated OHR components from measurements (Di Carlo, 2004;Yoshino et al, 2006;Sinha et al, 2008Sinha et al, , 2010Mao et al, 2010;Dolgorouky et al, 2012;Hansen et al, 2014;Nakashima et al, 2014;Nölscher et al, 2012Nölscher et al, , 2016Ramasamy et al, 2016;Zannoni et al, 2016Zannoni et al, , 2017 or from simple models (Ren et 10 al., 2006;Lee et al, 2009;Lou et al, 2010;Mogensen et al, 2011;Mao et al, 2012;Edwards et al, 2013;Kaiser et al, 2016;Whalley et al, 2016). Ferracci et al (2018) explored the impact of missing OHR estimated from surface observations on modeled global OH levels.…”

Section: Introductionmentioning

confidence: 99%

Constraining remote oxidation capacity with ATom observations

Travis¹,

Heald²,

Allen³

et al. 2020

Preprint

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Abstract. The global oxidation capacity, defined as the tropospheric mean concentration of the hydroxyl radical (OH), controls the lifetime of reactive trace gases in the atmosphere such as methane and carbon monoxide (CO). Models tend to underestimate the methane lifetime and CO concentrations throughout the troposphere, which is consistent with excessive OH. Approximately half the oxidation of methane and non-methane volatile organic compounds (VOCs) is thought to occur over the oceans where oxidant chemistry has received little validation due to a lack of observational constraints. We use observations from the first two deployments of the NASA ATom aircraft campaign during July–August 2016 and January–February 2017 to evaluate the oxidation capacity over the remote oceans and its representation in the GEOS-Chem chemical transport model. The model successfully simulates the magnitude and vertical profile of remote OH within the measurement uncertainties. Comparisons against the drivers of OH production (water vapor, ozone, and NOy concentrations, ozone photolysis frequencies) also show minimal bias with the exception of wintertime NOy, for which a model overestimate may indicate insufficient wet scavenging and/or missing loss on seasalt aerosol but large uncertainties remain that require further studies of NOy partitioning and removal in the troposphere. During the ATom-1 deployment, OH reactivity (OHR) below 3 km is significantly enhanced, and this is not captured by the sum of its measured components (cOHRobs) or by the model (cOHRmod). This enhancement could suggest missing reactive VOCs but cannot be explained by new estimates of ocean VOC sources and additional modeled reactivity in this region would be difficult to reconcile with the full suite of ATom measurement constraints. The model generally reproduces the magnitude and seasonality of cOHRobs but underestimates the contribution of oxygenated VOC, mainly acetaldehyde, which is severely underestimated throughout the troposphere despite its calculated lifetime of less than a day. Missing model acetaldehyde in previous studies was attributed to measurement uncertainties that have been largely resolved. Observations of peroxyacetic acid (PAA) provide new support for remote levels of acetaldehyde. The underestimate in modeled acetaldehyde and PAA is present throughout the year in both hemispheres and peaks during Northern Hemisphere summer. The addition of ocean VOC sources in the model increases annual surface cOHRmod by 10 % and improves model-measurement agreement for acetaldehyde particularly in winter but cannot resolve the model summertime bias. Doing so would require a 100 Tg yr−1 source of a long-lived unknown precursor throughout the year with significant additional emissions in the Northern Hemisphere summer. Improving the model bias for remote acetaldehyde and PAA is unlikely to fully resolve previously reported model global biases in OH and methane lifetime, suggesting that future work should examine the sources and sinks of OH over land.

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“…The diurnal cycle of OH total reactivity with a maximum around midday in a biogenic environment is well documented in literature from observations of OH reactivity for a Mediterranean forest (Zannoni et al, 2016), for temperate forests (Sinha et al, 2008;Ramasamy et al, 2016) but also for tropical forests Williams et al, 2016). The values of OH reactivity in or outside thermals in the present study are the lower bound of measurements over forests and gathered in Yang et al (2016), between 1 and 76 s −1 .…”

mentioning

confidence: 49%

“…As an example, over a Mediterranean forest, Zannoni et al (2016) measured the OH reactivity, as well as the concentration 30 of biogenic compounds. They found that isoprene was the dominant sink for OH and contributes up to 74% of OH total reactivity during daytime due to its high reactivity towards OH and its high concentration over the forested area.…”

mentioning

confidence: 99%

LES study of the impact of moist thermals on the oxidative capacity of the atmosphere in southern West Africa

Brosse¹,

Leriche²,

Mari³

et al. 2017

Preprint

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Abstract. The hydroxyl radical (OH) is a highly reactive specie and plays a key role in the oxidative capacity of the atmosphere. The total OH reactivity, corresponding to the inverse of OH lifetime, may have a significant fraction non-attributable to commonly measured compounds. The turbulence-driven segregation of OH and its reactants can cause substantial modification of averaged reaction rates, and thus of the total OH reactivity, when compared to a perfectly mixed assumption. We study the impact of turbulent mixing on the OH reactivity with Large-Eddy Simulations from the Meso-NH model coupled on-line with a 5 detailed chemistry mechanism in two contrasted regimes. Our findings show that the non-mixing of isoprene (resp. aldehydes) and OH leads to 30% decrease (resp. 16% increase) of the mean reaction rate at the top of the boundary layer and consequently to 9% decrease (resp. 5% increase) of the OH total reactivity in a biogenic (resp. anthropogenic) environment. Moreover, the total OH reactivity is highest inside thermals in both cases.

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OH reactivity and concentrations of biogenic volatile organic compounds in a Mediterranean forest of downy oak trees

Cited by 42 publications

References 68 publications

Comparison of OH reactivity measurements in the atmospheric simulation chamber SAPHIR

Comparison of OH reactivity measurements in the atmospheric simulation chamber SAPHIR

Constraining remote oxidation capacity with ATom observations

LES study of the impact of moist thermals on the oxidative capacity of the atmosphere in southern West Africa

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