OH and HO2 Chemistry in the urban atmosphere of New York City

Ren, Xinrong; Harder, Hartwig; Martínez, Mònica; Lesher, R.; Oliger, Angelique; Simpas, James Bernard; Brune, William H.; Schwab, James J.; Demerjian, Kenneth L.; He, Yi; Zhou, Xianliang; Gao, Haixiao

doi:10.1016/s1352-2310(03)00459-x

Cited by 303 publications

(280 citation statements)

References 36 publications

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“…Nashville, USA (SOS) 11.0 3.8 (Kovacs et al, 2003) New York, USA (PMTACS-NY2001) 18.8 0.7 (Ren et al, 2003a(Ren et al, , 2003b New York, USA (PMTACS-NY2004) 25.1 4.0 (Ren et al, 2006a) Mexico City, Mexico (MCMA-2003) 47.5 14.3 (Shirley et al, 2006) Houston, USA (TexAQS) 9.4 0.4 (Mao et al, 2010) Houston, USA (TRAMP2006) 12.24 0.03 (Mao et al, 2010) Paris, France (MEGAPOLI) 40.3 22.8 (Dolgorouky et al, 2012) Lille, France 7.4 0 (Hansen et al, 2015) London, UK (ClearfLo) 18.1 5.9 2.7 † (Whalley et al, 2016) Remote Michigan, USA (Prophet2000) 7.8 2.6 (Di Carlo et al, 2004) Hyytiälä, Finland (BFORM) 8.6 3.9 (Sinha et al, 2010) Hyytiälä, Finland (HUMPPA-COPEC2010) 11.5 8.9 (Nölscher et al, 2012) Rocky Mountains, USA (BEACHON-SRM08) 6.7 2.1 (Nakashima et al, 2014) Michigan, USA (CABINEX) 11.6 6.3 (Hansen et al, 2014) Amazon, Brazil (ATTO) dry season 49.6 35.8 …”

Section: Urbanmentioning

confidence: 99%

Global modelling of the total OH reactivity: investigations on the missing OH sink and its atmospheric implications

Ferracci¹,

Heimann²,

Abraham³

et al. 2018

Preprint

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Abstract. The hydroxyl radical (OH) plays a crucial role in the chemistry of the atmosphere as it initiates the removal of most trace gases. A number of field campaigns have observed the presence of a "missing" OH sink in a variety of regions across the planet. Comparison of direct measurements of the OH loss frequency, also known as total OH reactivity (kOH), with the 10 sum of individual known OH sinks (obtained via the simultaneous detection of species such as volatile organic compounds and nitrogen oxides) indicates that, in some cases, up to 80 % of kOH is unaccounted for. In this work, the UM-UKCA chemistry-climate model was used to investigate the wider implications of the missing reactivity on the oxidising capacity of the atmosphere. Simulations of the present-day atmosphere were performed and the model was evaluated against an array of field measurements to verify that the known OH sinks were reproduced well, with a resulting good agreement found for most 15 species. Following this, an additional sink was introduced to simulate the missing OH reactivity as an emission of a hypothetical molecule, X, which undergoes rapid reaction with OH. The magnitude and spatial distribution of this sink were underpinned by observations of the missing reactivity. Model runs showed that the missing reactivity accounted for on average 6 % of the total OH loss flux at the surface, and up to 50 % in regions where emissions of the additional sink were high. The lifetime of the hydroxyl radical was reduced by 3 % in the boundary layer, while tropospheric methane lifetime increased by 20 2 % when the additional OH sink was included. The UM-UKCA simulations also allowed us to establish the atmospheric implications of the newly characterised reactions of peroxy radicals (RO2) with OH. While the effects of this chemistry on kOH were minor, the reaction of the simplest peroxy radical, CH3O2, with OH was found to be a major sink for CH3O2 and source of HO2 over remote regions at the surface and in the free troposphere. Inclusion of this reaction in the model increased tropospheric methane lifetime by up to 3 %, depending on its product branching. Simulations based on the latest kinetic and 25 product information showed that this reaction cannot reconcile models with observations of atmospheric methanol, in contrast to recent suggestions.Atmos. Chem. Phys. Discuss., https://doi

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Section: Urbanmentioning

confidence: 99%

Global modelling of the total OH reactivity: investigations on the missing OH sink and its atmospheric implications

Ferracci¹,

Heimann²,

Abraham³

et al. 2018

Preprint

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“…7b) demonstrates that the HO2 artefact signal from RO2 radicals is unlikely to contribute to any model measured discrepancies under high NOx conditions as discussed below. An under-prediction in HO2 at elevated [NO] has been highlighted during a number of earlier urban studies (Martinez et al, 2003;Ren et al, 2013;Brune et al, 2016). Brune et al (2016) measured HO2 concentrations that were a factor of ten greater 25 than those predicted when NO concentrations reached 10 ppbv during the CalNex study which took place in Bakerfield, US.…”

Section: Observed and Modelled Hox Radical Behaviour As A Function Of Nomentioning

confidence: 99%

“…Griffith et al (2016) found that the level of agreement between modelled and measured HO2 was dependent on whether it was a weekday or weekend; the model under-predicted HO2 by a factor of 3.4 at weekends but agreed 15 well on weekdays (observed to modelled HO2 = 1.3). In a number of studies, the model-measurement discrepancy was noted to increase as NOx levels increased beyond ~1 ppbv (Martinez et al, 2003;Ren et al, 2013;Brune et al, 2016). This increasing under-prediction of the free-radicals (particularly for HO2) with increasing NOx concentrations observed may reflect inaccuracies in the radical propagation steps in the model, which cycle HO2 to OH.…”

Section: Introductionmentioning

confidence: 98%

“…Observations of OH and HO2 in the urban atmosphere have primarily been 5 made using fluorescence assay by gas expansion (FAGE), and comparisons with predicted radical concentrations using chemistry box models constrained with co-located radical precursor measurements have revealed varying levels of success in replicating observations. Radical concentrations have been reported to be under-predicted by models (Ren et al, 2003;Martinez et al, 2003;Emmerson et al, 2005a;Chen et al, 2010;Lu et al, 2012;Lu et al, 2013), over-predicted (George et al, 1999;Konrad et al, 2003;Dusanter et al, 2009) and, at times, models and measurements have been reported to be in 10 reasonable agreement, to within 40%, (Shirley et al, 2006;Emmerson et al, 2007;Kanaya et al, 2007;Sheehy et al, 2010;Elshorbany et al, 2012;Ren et al, 2013;Griffith et al, 2016). Often the level of agreement observed was found to be dependent on time of day (Brune et al, 2016); with poorest agreement between modelled and measured OH concentrations generally observed during the night.…”

Section: Introductionmentioning

confidence: 99%

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Understanding in situ ozone production in the summertime through radical observations and modelling studies during the Clean air for London project (ClearfLo)

Whalley¹,

Stone²,

Dunmore³

et al. 2017

Preprint

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Abstract. Measurements of OH, HO2, RO2i (alkene and aromatic related RO2) and total RO2 radicals taken during the ClearfLo campaign in central London in the summer of 2012 are presented. A photostationary steady-state calculation of OH which considered measured OH reactivity as the OH sink term and the measured OH sources (of which HO2+NO reaction and HONO photolysis dominated) compared well with the observed levels of OH. Comparison with calculations from a detailed box model utilising the Master Chemical Mechanism v3.2, however, highlighted a substantial discrepancy between radical 20 observations under lower NOx conditions ([NO] < 1 ppbv) typically experienced during the afternoon hours, and indicated that the model was missing a significant peroxy radical sink; the model over-predicted HO2 by up to a factor of 10 at these times.Known radical termination steps, such as HO2 uptake on aerosols, were not sufficient to reconcile the model measurement discrepancies alone suggesting other missing termination processes. This missing sink was most evident when the air reaching the site had previously passed over central London to the east and when elevated temperatures were experienced and, hence, 25 contained higher concentrations of VOC. Uncertainties in the degradation mechanism at low NOx of complex biogenic and diesel related VOC species which were particularly elevated and dominated OH reactivity under these easterly flows, may account for some of the model measurement disagreement. Under higher [NO] (>3 ppbv) the box model increasingly underpredicted total [RO2]. The modelled and observed HO2 were in agreement, however, under elevated NO concentrations ranging from 7 -15 ppbv. 30The model uncertainty under low NO conditions leads to more ozone production predicted using modelled peroxy radical concentrations (~3 ppbv hr -1 ) versus ozone production from peroxy radicals measured (~1 ppbv hr -1 ). Conversely, ozone 2 production derived from the predicted peroxy radicals is up to an order of magnitude lower than from the observed peroxy radicals as [NO] increases beyond 7 ppbv due to the model under-prediction of RO2 under these conditions.

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“…These reactions constitute the first step in the process of photochemical O 3 production in the atmosphere. Total OH reactivity measurements in the urban atmosphere have been conducted in New York City, USA (Ren et al, 2003a(Ren et al, , 2003b, Mexico City, Mexico (Shirley et al, 2006), Mainz, Germany (Sinha et al, 2008), Pearl River Delta, China (Hofzumahaus et al, 2009;Lou et al, 2010), and Houston, USA (Mao et al, 2010). The values of the OH reactivity observed during these measurements vary widely, between 10 and 200 s À1 , which reflects considerable regional diversity in the urban atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Air quality diagnosis from comprehensive observations of total OH reactivity and reactive trace species in urban central Tokyo

Yoshino

Nakashima

Miyazaki

et al. 2012

Atmospheric Environment

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a b s t r a c tWe have conducted a comprehensive observational study to determine the mixing ratios of atmospheric chemical species and total OH reactivity in central Tokyo, in order to diagnose the air quality during summer and winter 2007 and autumn 2009. Concentrations of over 70 reactive trace species were continuously measured throughout each season. The total OH reactivity was measured directly using a laser-induced pump and probe technique. The observed chemical species exhibited seasonal variations. There was a good correlation between NO and CO in winter, but not in summer. This indicates that during winter, vehicle exhaust provided a significant source of NO in central Tokyo, while photolysis of NO 2 was dominant in summer. Similar values (approximately 30 s À1 ) for the averaged total OH reactivity were observed in both summer and autumn during the daytime. However, VOCs accounted for a larger percentage of the OH reactivity in summer, while NO x was more dominant in autumn. We find that photochemical processes leading to oxidant production via VOCs dominated OH removal in summer, while the production of nitric acid from the reaction between OH and NO 2 was dominant in autumn, by-passing the oxidant production pathways and resulting in reduced oxidant formation.

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OH and HO2 Chemistry in the urban atmosphere of New York City

Cited by 303 publications

References 36 publications

Global modelling of the total OH reactivity: investigations on the missing OH sink and its atmospheric implications

Global modelling of the total OH reactivity: investigations on the missing OH sink and its atmospheric implications

Understanding in situ ozone production in the summertime through radical observations and modelling studies during the Clean air for London project (ClearfLo)

Air quality diagnosis from comprehensive observations of total OH reactivity and reactive trace species in urban central Tokyo

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