Direct ozone production rate measurements and their use in assessing ozone source and receptor regions for Houston in 2013

Baier, Bianca C.; Brune, William H.; Lefer, B. L.; Miller, David O.; Martins, D. K.

doi:10.1016/j.atmosenv.2015.05.033

Cited by 36 publications

(58 citation statements)

References 22 publications

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“…The Measurement of Ozone Production Sensor (MOPS) directly measures P(O 3 ) and can help to evaluate O 3 formation calculated from chemical mechanisms via Eqs. (2)- (4) (Cazorla and Brune, 2010;Baier et al, 2015). Observed P(O 3 ) has also shown similar discrepancies to modeled P(O 3 ) at high NO or NO x .…”

Section: Introductionmentioning

confidence: 68%

Higher measured than modeled ozone production at increased NOx levels in the Colorado Front Range

et al. 2017

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Abstract. Chemical models must correctly calculate the ozone formation rate, P(O 3 ), to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O 3 ) calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O 3 ) is high. One way to test mechanisms is to compare modeled P(O 3 ) to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS) directly measured net P(O 3 ) in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O 3 ) was compared to rates calculated by a photochemical box model that was constrained by measurements of other chemical species and that used a lumped chemical mechanism and a more explicit one. Median observed P(O 3 ) was up to a factor of 2 higher than that modeled during early morning hours when nitric oxide (NO) levels were high and was similar to modeled P(O 3 ) for the rest of the day. While all interferences and offsets in this new method are not fully understood, simulations of these possible uncertainties cannot explain the observed P(O 3 ) behavior. Modeled and measured P(O 3 ) and peroxy radical (HO 2 and RO 2 ) discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds coemitted with NO could be one plausible solution to the P(O 3 ) discrepancy, such a source has not been identified and does not fully explain the peroxy radical model-data mismatch. If the MOPS accurately depicts atmospheric P(O 3 ), then these results would imply that P(O 3 ) in Golden, CO, would be NO x -sensitive for more of the day than what is calculated by models, extending the NO x -sensitive P(O 3 ) regime from the afternoon further into the morning. These results couldPublished by Copernicus Publications on behalf of the European Geosciences Union. 11274 B. C. Baier et al.: Higher measured than modeled ozone production affect ozone reduction strategies for the region surrounding Golden and possibly other areas that do not comply with national ozone regulations. Thus, it is important to continue the development of this direct ozone measurement technique to understand P(O 3 ), especially under high-NO x regimes.

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Section: Introductionmentioning

confidence: 68%

Higher measured than modeled ozone production at increased NOx levels in the Colorado Front Range

et al. 2017

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“…Previous studies (Cazorla and Brune, 2010;Baier et al, 2015) have shown that measurements of ambient ozone production rates are feasible. Baier et al (2015) reported that the zero of their MOPS instrument was achieved by removing the UV filter from the reference chamber for a full day to record a diurnal profile of O x , which was then subtracted from the raw O x measurements on other days.…”

Section: Comparison To Previously Published Instruments and Potentialmentioning

confidence: 99%

“…In the most recent version of the instrument (Baier et al, 2015), the conversion efficiency was increased to 88-97 % for NO 2 mixing ratios lower than 35 ppbv using a highly efficient UV lamp that provided 10 times more photons than the light-emitting diodes. In the MOPS instrument, however, the conversion efficiency depends on NO 2 levels, as well as on the intensity of the lamp that could drift during a long period of use in the field.…”

Section: Quantification Of the Conversion Efficiencymentioning

confidence: 99%

“…Baier et al (2015) reported that the zero of their MOPS instrument was achieved by removing the UV filter from the reference chamber for a full day to record a diurnal profile of O x , which was then subtracted from the raw O x measurements on other days. This zeroing procedure was also tested on the OPR instrument, but led to unrealistically high ambient P (O x ) values of approximately 40 ppbv h −1 for the low-NO x forested environment of IRRONIC.…”

Section: Comparison To Previously Published Instruments and Potentialmentioning

confidence: 99%

“…Recently, an improved version of the MOPS instrument was deployed during the NASA's DISCOVER-AQ field campaign in 2013, in Houston, Texas (Baier et al, 2015). Wall effects were reduced by improving the design of the sampling chambers and the airflow characteristics.…”

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confidence: 99%

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Development of an instrument for direct ozone production rate measurements: measurement reliability and current limitations

et al. 2018

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Abstract. Ground-level ozone (O 3 ) is an important pollutant that affects both global climate change and regional air quality, with the latter linked to detrimental effects on both human health and ecosystems. Ozone is not directly emitted in the atmosphere but is formed from chemical reactions involving volatile organic compounds (VOCs), nitrogen oxides (NO x = NO + NO 2 ) and sunlight. The photochemical nature of ozone makes the implementation of reduction strategies challenging and a good understanding of its formation chemistry is fundamental in order to develop efficient strategies of ozone reduction from mitigation measures of primary VOCs and NO x emissions.An instrument for direct measurements of ozone production rates (OPRs) was developed and deployed in the field as part of the IRRONIC (Indiana Radical, Reactivity and Ozone Production Intercomparison) field campaign. The OPR instrument is based on the principle of the previously published MOPS instrument (Measurement of Ozone Production Sensor) but using a different sampling design made of quartz flow tubes and a different O x (O 3 and NO 2 ) conversiondetection scheme composed of an O 3 -to-NO 2 conversion unit and a cavity attenuated phase shift spectroscopy (CAPS) NO 2 monitor. Tests performed in the laboratory and in the field, together with model simulations of the radical chemistry occurring inside the flow tubes, were used to assess (i) the reliability of the measurement principle and (ii) potential biases associated with OPR measurements. This publication reports the first field measurements made using this instrument to illustrate its performance. The results showed that a photo-enhanced loss of ozone inside the sampling flow tubes disturbs the measurements. This issue needs to be solved to be able to perform accurate ambient measurements of ozone production rates with the instrument described in this study. However, an attempt was made to investigate the OPR sensitivity to NO x by adding NO inside the instrument. This type of investigations allows checking whether our understanding of the turnover point between NO x -limited and NO x -saturated regimes of ozone production is well understood and does not require measuring ambient OPR but instead only probing the change in ozone production when NO is added. During IRRONIC, changes in ozone production rates ranging from the limit of detection (3σ ) of 6.2 ppbv h −1 up to 20 ppbv h −1 were observed when 6 ppbv of NO was added into the flow tubes.

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Sources and composition of PM_2.5 in the Colorado Front Range during the DISCOVER‐AQ study

et al. 2017

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Measurements of particulate matter (PM2.5) chemical composition were carried out in Golden, CO, during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER‐AQ) field study. Chemical composition was dominated by organic compounds, which comprised an average of 75% of the PM2.5 mass throughout the study. Most of the organic matter was secondary (i.e., secondary organic aerosol) and appears to derive predominantly from regional sources, rather than the Denver metropolitan area. The concentration and composition of PM2.5 in Golden were strongly influenced by highly regular wind patterns and the site's close proximity to the mountains (~5 km). This second factor may be the cause of distinct differences between observations in Golden and those in downtown Denver, despite a distance between the sites of only ~15 km. Concentrations of aerosol nitrate, ammonium, and elemental carbon increased significantly during the daytime when the winds were from the northeast, indicating a strong local source for these compounds. Local sources of dust appeared to minimally impact the Golden site, although this was not likely representative of other conditions in the Colorado Front Range. Conversely, dust that had undergone long‐range transport from the southwestern U.S. likely impacted the entire Colorado Front Range, including Golden. During this event, water‐soluble Ca2+ concentrations exceeded 1 µg m−3, and the PM2.5/PM10 ratio reached its lowest level throughout the study. The long‐range transport of wildfire emissions also impacted the Colorado Front Range for 1–2 days during DISCOVER‐AQ. The smoke event was characterized by high concentrations of organics and water‐soluble K+. The results show a complex array of sources, and atmospheric processes influence summertime PM in the Colorado Front Range.

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Direct ozone production rate measurements and their use in assessing ozone source and receptor regions for Houston in 2013

Cited by 36 publications

References 22 publications

Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range

Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range

Development of an instrument for direct ozone production rate measurements: measurement reliability and current limitations

Sources and composition of PM_2.5 in the Colorado Front Range during the DISCOVER‐AQ study

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Direct ozone production rate measurements and their use in assessing ozone source and receptor regions for Houston in 2013

Cited by 36 publications

References 22 publications

Higher measured than modeled ozone production at increased NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; levels in the Colorado Front Range

Higher measured than modeled ozone production at increased NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; levels in the Colorado Front Range

Development of an instrument for direct ozone production rate measurements: measurement reliability and current limitations

Sources and composition of PM2.5 in the Colorado Front Range during the DISCOVER‐AQ study

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Product

Resources

About

Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range

Higher measured than modeled ozone production at increased NO<sub><i>x</i></sub> levels in the Colorado Front Range

Sources and composition of PM_2.5 in the Colorado Front Range during the DISCOVER‐AQ study