scholarly journals Characterization of ozone production in San Antonio, Texas, using measurements of total peroxy radicals

2019 ◽  
Vol 19 (5) ◽  
pp. 2845-2860 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
Walter B. Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Peroxy Radical ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Entire Region ◽  
Volatile Organic ◽  
In Situ Observations ◽  
Study Sites

Abstract. Observations of total peroxy radical concentrations ([XO2] ≡ [RO2] + [HO2]) made by the Ethane CHemical AMPlifier (ECHAMP) and concomitant observations of additional trace gases made on board the Aerodyne Mobile Laboratory (AML) during May 2017 were used to characterize ozone production at three sites in the San Antonio, Texas, region. Median daytime [O3] was 48 ppbv at the site downwind of central San Antonio. Higher concentrations of NO and XO2 at the downwind site also led to median daytime ozone production rates (P(O3)) of 4.2 ppbv h−1, a factor of 2 higher than at the two upwind sites. The 95th percentile of P(O3) at the upwind site was 15.1 ppbv h−1, significantly lower than values observed in Houston. In situ observations, as well as satellite retrievals of HCHO and NO2, suggest that the region was predominantly NOx-limited. Only approximately 20 % of observations were in the VOC-limited regime, predominantly before 11:00 EST, when ozone production was low. Biogenic volatile organic compounds (VOCs) comprised 55 % of total OH reactivity at the downwind site, with alkanes and non-biogenic alkenes responsible for less than 10 % of total OH reactivity in the afternoon, when ozone production was highest. To control ozone formation rates at the three study sites effectively, policy efforts should be directed at reducing NOx emissions. Observations in the urban center of San Antonio are needed to determine whether this policy is true for the entire region.

scholarly journals Characterization of Ozone Production in San Antonio, Texas Using Observations of Total Peroxy Radicals

2018 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
W. Berk Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Urban Center ◽  
Entire Region ◽  
Volatile Organic ◽  
In Situ Observations ◽  
Study Sites

Abstract. Observations of total peroxy radicals (XO2 = RO2 + HO2) made by the Ethane CHemical AMPlifier (ECHAMP) and concomitant observations of additional trace gases made onboard the Aerodyne Mobile Laboratory (AML) during May 2017 were used to characterize ozone production at three sites in the San Antonio, Texas region. Median daytime [O3] was 48 ppbv at the site downwind of central San Antonio. Higher concentrations of NO and XO2 at the downwind site also led to median daytime ozone production rates (P(O3)) of 4.2 ppbv hr−1, a factor of two higher than at the two upwind sites. The 95th percentile of P(O3) at the upwind site was 15.1 ppbv hr−1, significantly lower than values observed in Houston. In situ observations, as well as satellite retrievals of HCHO and NO3, suggest that the region is NOx limited for times after approximately 09:00 local time, before which ozone production is VOC-limited. Biogenic volatile organic compounds (VOC) comprised 55 % of total OH reactivity at the downwind site, with alkanes and non-biogenic alkenes responsible for less than 10 % of total OH reactivity in the afternoon, when ozone production was highest. To control ozone formation rates at the three study sites effectively, policy efforts should be directed at reducing NOx emissions. Observations in the urban center of San Antonio are needed to determine whether this policy is true for the entire region.

Unexpected Fast Monoterpene Oxidation In Eastern China

2021 ◽  
Author(s):  
Haichao Wang
Keyword(s):  
Eastern China ◽  
Field Measurements ◽  
Ozone Production ◽  
Nitrate Radical ◽  
Peroxy Radicals ◽  
Ozone Pollution ◽  
Volatile Organic ◽  
Secondary Aerosols ◽  
Photochemical Ozone

<p>Monoterpene plays an important role in the formation of secondary aerosols and ozone in the troposphere. However, the field characterization of monoterpene chemistry in ozone pollution is still very sparse. Here we report fast daytime oxidation of monoterpene by hydroxyl radical, nitrate radical and ozone based on field measurements in Eastern China. We find fast monoterpene oxidation produces peroxy radicals efficiently and enhances the photochemical ozone production largely with an additional 8.6 ppb of ozone production per day on average (14%), whose effect was even more important than that of isoprene chemistry in the analyzed dataset. We propose that the reduction of anthropogenic volatile organic compounds should be much more stringent in the presence of high monoterpenes to alleviating ozone pollution.</p>

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

2017 ◽  
Author(s):  
Lisa K. Whalley ◽  
Daniel Stone ◽  
Rachel Dunmore ◽  
Jacqueline Hamilton ◽  
James R. Hopkins ◽  
...  
Keyword(s):  
Peroxy Radical ◽  
Box Model ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Sink Term ◽  
Modelling Studies ◽  
Order Of Magnitude ◽  
Clean Air

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 observations under lower NOx conditions ([NO]  3 ppbv) the box model increasingly under-predicted total [RO2]. The modelled and observed HO2 were in agreement, however, under elevated NO concentrations ranging from 7–15 ppbv. The 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 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.

scholarly journals Measurement report: Photochemical production and loss rates of formaldehyde and ozone across Europe

2021 ◽  
Vol 21 (24) ◽  
pp. 18413-18432
Author(s):  
Clara M. Nussbaumer ◽  
John N. Crowley ◽  
Jan Schuladen ◽  
Jonathan Williams ◽  
Sascha Hafermann ◽  
...  
Keyword(s):  
Trace Gases ◽  
Ozone Production ◽  
Trace Gas ◽  
Coastal Site ◽  
Sources And Sinks ◽  
Oxidation Of Methane ◽  
Volatile Organic ◽  
Mountain Site ◽  
In Situ Observations

Abstract. Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO), which is an important trace gas impacting the HOx (≡ HO2 + OH) budget and the concentration of ozone (O3). In this study, we present the formation and destruction terms of ambient HCHO and O3 calculated from in situ observations of various atmospheric trace gases measured at three different sites across Europe during summertime. These include a coastal site in Cyprus, in the scope of the Cyprus Photochemistry Experiment (CYPHEX) in 2014, a mountain site in southern Germany, as part of the Hohenpeißenberg Photochemistry Experiment (HOPE) in 2012, and a forested site in Finland, where measurements were performed during the Hyytiälä United Measurements of Photochemistry and Particles (HUMPPA) campaign in 2010. We show that, at all three sites, formaldehyde production from the OH oxidation of methane (CH4), acetaldehyde (CH3CHO), isoprene (C5H8) and methanol (CH3OH) can almost completely balance the observed loss via photolysis, OH oxidation and dry deposition. Ozone chemistry is clearly controlled by nitrogen oxides (NOx ≡ NO + NO2) that include O3 production from NO2 photolysis and O3 loss via the reaction with NO. Finally, we use the HCHO budget calculations to determine whether net ozone production is limited by the availability of VOCs (volatile organic compounds; VOC-limited regime) or NOx (NOx-limited regime). At the mountain site in Germany, O3 production is VOC limited, whereas it is NOx limited at the coastal site in Cyprus. The forested site in Finland is in the transition regime.

scholarly journals The changing role of organic nitrates in the removal and transport of NO<sub>x</sub>

2019 ◽  
Author(s):  
Paul S. Romer Present ◽  
Azimeh Zare ◽  
Ronald C. Cohen
Keyword(s):  
Air Pollution ◽  
The United States ◽  
Ozone Production ◽  
Organic Nitrates ◽  
Volatile Organic ◽  
Direct Formation ◽  
In Situ Observations ◽  
Changing Role

Abstract. A better understanding of the chemistry of nitrogen oxides (NONOx) is crucial to effectively reducing air pollution and predicting future air quality. The response of NOx lifetime to perturbations in emissions or in the climate system is set in large part by whether NOx loss occurs primarily by the direct formation of HNO3 or through the formation of alkyl and multifunctional nitrates (RONO2). Using 15 years of detailed in situ observations, we show that in the summertime continental boundary layer the relative importance of these two pathways can be well approximated by the relative likelihood that OH will react with NO2 or instead with a volatile organic compound (VOC). Over the past decades, changes in anthropogenic emissions of both NONOx and VOCs have led to a significant increase in the overall importance of RONO2 chemistry to NONOx loss. We find that this shift is associated with a decreased effectiveness of NONOx emissions reductions on ozone production in polluted areas and increased transport of NONOx from source to receptor regions. This change in chemistry, combined with changes in the spatial pattern of NONOx emissions, is observed to be leading to a flatter distribution of NO2 across the United States, potentially transforming ozone air pollution from a local issue into a regional one.

scholarly journals Supplementary material to "Characterization of Ozone Production in San Antonio, Texas Using Observations of Total Peroxy Radicals"

2018 ◽  
Author(s):  
Daniel C. Anderson ◽  
Jessica Pavelec ◽  
Conner Daube ◽  
Scott C. Herndon ◽  
W. Berk Knighton ◽  
...  
Keyword(s):  
San Antonio ◽  
Ozone Production ◽  
Peroxy Radicals ◽  
Supplementary Material

scholarly journals Anthropogenic enhancements to production of highly oxygenated molecules from autoxidation

2019 ◽  
Vol 116 (14) ◽  
pp. 6641-6646 ◽  
Author(s):  
Havala O. T. Pye ◽  
Emma L. D’Ambro ◽  
Ben H. Lee ◽  
Siegfried Schobesberger ◽  
Masayuki Takeuchi ◽  
...  
Keyword(s):  
Fine Particulate Matter ◽  
Peroxy Radicals ◽  
Dominant Component ◽  
Fine Particulate ◽  
Biogenic Voc ◽  
Aircraft Observations ◽  
Volatile Organic ◽  
Climate Interactions ◽  
Urban Plume

Atmospheric oxidation of natural and anthropogenic volatile organic compounds (VOCs) leads to secondary organic aerosol (SOA), which constitutes a major and often dominant component of atmospheric fine particulate matter (PM2.5). Recent work demonstrates that rapid autoxidation of organic peroxy radicals (RO2) formed during VOC oxidation results in highly oxygenated organic molecules (HOM) that efficiently form SOA. As NOxemissions decrease, the chemical regime of the atmosphere changes to one in which RO2autoxidation becomes increasingly important, potentially increasing PM2.5, while oxidant availability driving RO2formation rates simultaneously declines, possibly slowing regional PM2.5formation. Using a suite of in situ aircraft observations and laboratory studies of HOM, together with a detailed molecular mechanism, we show that although autoxidation in an archetypal biogenic VOC system becomes more competitive as NOxdecreases, absolute HOM production rates decrease due to oxidant reductions, leading to an overall positive coupling between anthropogenic NOxand localized biogenic SOA from autoxidation. This effect is observed in the Atlanta, Georgia, urban plume where HOM is enhanced in the presence of elevated NO, and predictions for Guangzhou, China, where increasing HOM-RO2production coincides with increases in NO from 1990 to 2010. These results suggest added benefits to PM2.5abatement strategies come with NOxemission reductions and have implications for aerosol–climate interactions due to changes in global SOA resulting from NOxinteractions since the preindustrial era.

scholarly journals Diel peroxy radicals in a semi industrial coastal area: nighttime formation of free radicals

2012 ◽  
Vol 12 (8) ◽  
pp. 19529-19570 ◽  
Author(s):  
M. D. Andrés-Hernández ◽  
D. Kartal ◽  
J. N. Growley ◽  
V. Sinha ◽  
E. Regelin ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Trace Gases ◽  
Peroxy Radical ◽  
Industrial Area ◽  
Diurnal Variations ◽  
Peroxy Radicals ◽  
Industrial Emissions ◽  
Air Masses ◽  
Volatile Organic ◽  
Organic Trace

Abstract. Peroxy radicals were measured by a PeRCA (Peroxy Radical Chemical Amplifier) instrument in the boundary layer during the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) campaign at a coastal, forested site influenced by urban-industrial emissions in Southern Spain in late autumn. Total peroxy radicals (RO2* = HO2 + ΣRO2) generally showed a daylight maximum between 10 and 50 pptv at 13:00 UTC, with an average of 18 pptv over the 15 days of measurements. Emissions from the industrial area of Huelva often impacted the measurement site at night during the campaign. The processing of significant levels of anthropogenic organics leads to an intense nocturnal radical chemistry accompanied by formation of organic peroxy radicals at comparable levels to those of summer photochemical conditions with peak events up to 60–80 pptv. The RO2 production initiated by reactions of NO3 with organic trace gases was estimated to be significant but not sufficient to account for the concentrations of RO2* observed in air masses carrying high pollutant loading. The nocturnal production of peroxy radicals seems therefore to be dominated by ozonolysis of volatile organic compounds. RO2* diurnal variations were consistent with other HO2 measurements available at the site. HO2/RO2* ratios generally varied between 0.3 and 0.4 in all wind directions. Occasional HO2/RO2* ≥ 1 seemed to be associated with periods of high RO2* variability and with RO2 interferences in the HO2 measurement in air masses with high RO2 load.

Characterization of Remote Sensing Albedo Over Sloped Surfaces Based on DART Simulations and In Situ Observations

2018 ◽  
Vol 123 (16) ◽  
pp. 8599-8622 ◽  
Author(s):  
Shengbiao Wu ◽  
Jianguang Wen ◽  
Dongqin You ◽  
Dalei Hao ◽  
Xingwen Lin ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Observations

Global Assessment of Semidiurnal Internal Tide Aliasing in Argo Profiles

2019 ◽  
Vol 49 (10) ◽  
pp. 2523-2533 ◽  
Author(s):  
Tyler D. Hennon ◽  
Matthew H. Alford ◽  
Zhongxiang Zhao
Keyword(s):  
Internal Waves ◽  
Internal Tide ◽  
Internal Tides ◽  
Stationary Mode ◽  
Argo Floats ◽  
New Information ◽  
In Situ Observations ◽  
Argo Profiles

AbstractThough unresolved by Argo floats, internal waves still impart an aliased signal onto their profile measurements. Recent studies have yielded nearly global characterization of several constituents of the stationary internal tides. Using this new information in conjunction with thousands of floats, we quantify the influence of the stationary, mode-1 M2 and S2 internal tides on Argo-observed temperature. We calculate the in situ temperature anomaly observed by Argo floats (usually on the order of 0.1°C) and compare it to the anomaly expected from the stationary internal tides derived from altimetry. Globally, there is a small, positive correlation between the expected and in situ signals. There is a stronger relationship in regions with more intense internal waves, as well as at depths near the nominal mode-1 maximum. However, we are unable to use this relationship to remove significant variance from the in situ observations. This is somewhat surprising, given that the magnitude of the altimetry-derived signal is often on a similar scale to the in situ signal, and points toward a greater importance of the nonstationary internal tides than previously assumed.

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