Airborne and ground‐based observations of a weekend effect in ozone, precursors, and oxidation products in the California South Coast Air Basin

Pollack, I. B.; Ryerson, T. B.; Trainer, M.; Parrish, D. D.; Andrews, A. E.; Atlas, Elliot L.; Blake, Donald R.; Brown, Steven S.; Commane, R.; Daube, Bruce C.; Gouw, J. A. de; Dubé, W. P.; Flynn, James; Frost, G. J.; Gilman, J. B.; Grossberg, N.; Holloway, J. S.; Kofler, J.; Kort, E. A.; Kuster, W. C.; Lang, P. M.; Lefer, B. L.; Lueb, R.; Neuman, J. Andrew; Nowak, John B.; Novelli, P. C.; Peischl, J.; Perring, A. E.; Roberts, J. M.; Santoni, G. W.; Schwarz, J. P.; Spackman, J. R.; Wagner, Nick; Warneke, C.; Washenfelder, R. A.; Wofsy, Steven C.; Xiang, Bin

doi:10.1029/2011jd016772

Cited by 111 publications

(180 citation statements)

References 75 publications

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“…Titration does not increase the sum of O 3 and NO 2 , whereas photochemistry with VOCs does. Therefore, variations in O x levels indicate that photochemistry with VOCs is important (Pollack et al, 2012). The average diurnal mixing ratios of O 3 and O x from NAPS measurements showing a maximum in the afternoon and being slightly higher on the weekends is also consistent with the average diurnal mixing ratios of HCHO showing a peak in the afternoon on weekends (Fig.…”

Section: O 3 No No 2 and Hchosupporting

confidence: 69%

Long-path measurements of pollutants and micrometeorology over Highway 401 in Toronto

et al. 2017

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Abstract. Traffic emissions contribute significantly to urban air pollution. Measurements were conducted over Highway 401 in Toronto, Canada, with a long-path Fourier transform infrared (FTIR) spectrometer combined with a suite of micrometeorological instruments to identify and quantify a range of air pollutants. Results were compared with simultaneous in situ observations at a roadside monitoring station, and with output from a special version of the operational Canadian air quality forecast model (GEM-MACH). Elevated mixing ratios of ammonia (0-23 ppb) were observed, of which 76 % were associated with traffic emissions. Hydrogen cyanide was identified at mixing ratios between 0 and 4 ppb. Using a simple dispersion model, an integrated emission factor of on average 2.6 g km −1 carbon monoxide was calculated for this defined section of Highway 401, which agreed well with estimates based on vehicular emission factors and observed traffic volumes. Based on the same dispersion calculations, vehicular average emission factors of 0.04, 0.36, and 0.15 g km −1 were calculated for ammonia, nitrogen oxide, and methanol, respectively.

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Section: O 3 No No 2 and Hchosupporting

confidence: 69%

Long-path measurements of pollutants and micrometeorology over Highway 401 in Toronto

et al. 2017

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“…Also, the OPE x,CAPS in this study is close to those reported in other cities, e.g., 2.5-4 for Nashville urban plume [Nunnermacker et al, 1998], 2.2-4.2 in New York City [Kleinman et al, 2000], and slightly lower than the range of 3.9-4.7 observed in Los Angeles, California [Pollack et al, 2012]. However, the OPE x in Beijing during summertime is observed to be higher by a factor of 2.4 compared to wintertime , indicating higher ozone production efficiency in summer than winter.…”

Section: Ozone Production Efficiency (Ope X )mentioning

confidence: 50%

“…Also, the low NO x concentration generally would lead to the high OPE x values (Figure 8). Another reason might be related to the wellknown phenomenon commonly referred to as the "weekend ozone effect" or "holiday effect" [Fujita et al, 2003;Pollack et al, 2012;Yarwood et al, 2003]. In these cases, Chou et al [2011] and Sun et al [2011] observed that enhancements in ozone are caused by reductions in NO x emissions on weekends that lead to enhancements in VOC/NO x ratio and ozone production efficiency.…”

Section: Ozone Production Efficiency (Ope X )mentioning

confidence: 99%

Nitrogen dioxide measurement by cavity attenuated phase shift spectroscopy (CAPS) and implications in ozone production efficiency and nitrate formation in Beijing, China

Sun

Liu

et al. 2013

JGR Atmospheres

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Nitrogen dioxide (NO2) is a key species in studying photochemical smog and formation mechanisms of nitrate in fine particles. However, the conventional commercially available chemiluminescence (CL)‐based method often has uncertainties in measuring NO2 because of interferences with other reactive nitrogen species. In this study, an Aerodyne Cavity Attenuated Phase Shift Spectroscopy (CAPS) NO2 monitor that essentially has no interferences with nitrogen containing species was deployed in Beijing for the first time during August 2012. The CAPS NO2 monitor is highly sensitive with a detection limit (3σ) of 46.6 ppt for 1 min integration. The NO2 measured by CAPS shows overall agreement with that from CL, yet large differences up to 20% were also observed in the afternoon. Further, the discrepancies of NO2 measurements between CAPS and CL appear to be NOz dependent with larger differences at higher NOz concentrations (e.g., > 14 ppb). As a result, the ozone production efficiency of NOx (OPEx) derived from the correlations of Ox‐NOz with the CL NO2 can be overestimated by 19–37% in Beijing. The daily OPEx calculated with the CAPS NO2 ranges from 1.0 to 6.8 ppb/ppb with an average (±1σ) of 2.6 (±1.3) for the entire study. The relatively low OPEx and the relationship between OPEx and NOx suggest that ozone production chemistry is VOC sensitive during summer in Beijing. Two case studies further show that high concentrations of NOx can significantly enhance the formation of nitrate in fine particles in the presence of high O3 and favorable meteorological conditions.

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“…[49] It is well known that in California and the South Coast Air Basin, a large decrease in on-road diesel vehicle activity occurs on weekends, which leads to significant reductions in atmospheric species associated with diesel vehicles such as NO x , EC, specific VOCs, and particulate nitrate [Marr and Harley, 2002;Millstein et al, 2008;Pollack et al, 2012]. To explore if primary organic aerosols show an analogous weekend effect in Pasadena during CalNex, the diurnal cycles for HOA, EC, rBC, CIOA, CO, and benzene are plotted for weekdays and Sundays separately in Figure 10.…”

Section: Correlation Of Oxygenated Organic Aerosols With the Photochementioning

confidence: 99%

Organic aerosol composition and sources in Pasadena, California, during the 2010 CalNex campaign

et al. 2013

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Organic aerosols (OA) in Pasadena are characterized using multiple measurements from the California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign. Five OA components are identified using positive matrix factorization including hydrocarbon‐like OA (HOA) and two types of oxygenated OA (OOA). The Pasadena OA elemental composition when plotted as H : C versus O : C follows a line less steep than that observed for Riverside, CA. The OOA components from both locations follow a common line, however, indicating similar secondary organic aerosol (SOA) oxidation chemistry at the two sites such as fragmentation reactions leading to acid formation. In addition to the similar evolution of elemental composition, the dependence of SOA concentration on photochemical age displays quantitatively the same trends across several North American urban sites. First, the OA/ΔCO values for Pasadena increase with photochemical age exhibiting a slope identical to or slightly higher than those for Mexico City and the northeastern United States. Second, the ratios of OOA to odd‐oxygen (a photochemical oxidation marker) for Pasadena, Mexico City, and Riverside are similar, suggesting a proportional relationship between SOA and odd‐oxygen formation rates. Weekly cycles of the OA components are examined as well. HOA exhibits lower concentrations on Sundays versus weekdays, and the decrease in HOA matches that predicted for primary vehicle emissions using fuel sales data, traffic counts, and vehicle emission ratios. OOA does not display a weekly cycle—after accounting for differences in photochemical aging —which suggests the dominance of gasoline emissions in SOA formation under the assumption that most urban SOA precursors are from motor vehicles.

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Airborne and ground‐based observations of a weekend effect in ozone, precursors, and oxidation products in the California South Coast Air Basin

Cited by 111 publications

References 75 publications

Long-path measurements of pollutants and micrometeorology over Highway 401 in Toronto

Long-path measurements of pollutants and micrometeorology over Highway 401 in Toronto

Nitrogen dioxide measurement by cavity attenuated phase shift spectroscopy (CAPS) and implications in ozone production efficiency and nitrate formation in Beijing, China

Organic aerosol composition and sources in Pasadena, California, during the 2010 CalNex campaign

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