Interpretation of decadal-scale ozone production efficiency in the Seoul Metropolitan Area: Implication for ozone abatement

2020 ◽  
Vol 243 ◽  
pp. 117846
Author(s):  
Lim-Seok Chang ◽  
Jin-Young Choi ◽  
Jongseok Son ◽  
Sangbo Lee ◽  
Daegyun Lee ◽  
...  
Keyword(s):  
Metropolitan Area ◽  
Production Efficiency ◽  
Ozone Production ◽  
Seoul Metropolitan Area ◽  
Decadal Scale

scholarly journals Integration of Airborne and Ground Observations of Nitryl Chloride in the Seoul Metropolitan Area and the Implications on Regional Oxidation Capacity During KORUS-AQ 2016

2018 ◽  
Author(s):  
Daun Jeong ◽  
Roger Seco ◽  
Dasa Gu ◽  
Youngro Lee ◽  
Benjamin A. Nault ◽  
...  
Keyword(s):  
Metropolitan Area ◽  
Box Model ◽  
Ozone Production ◽  
Integrated Analysis ◽  
Back Trajectory ◽  
Night Time ◽  
Model Calculations ◽  
Nitryl Chloride ◽  
Seoul Metropolitan Area ◽  
The Impact

Abstract. Nitryl chloride (ClNO2) is a radical reservoir species that releases chlorine radicals upon photolysis. An integrated analysis of the impact of ClNO2 on regional photochemistry in the Seoul Metropolitan Area (SMA) during the Korean-United States-Air Quality (KORUS-AQ) 2016 field campaign is presented. Comprehensive multiplatform observations were conducted aboard the NASA DC-8 and at two ground sites (Olympic Park, OP; Taehwa Research Forest, TRF), representing an urbanized area and a forested region downwind, respectively. The overall diurnal variations of ClNO2 in both sites appeared similar but the night time variation were systematically different. For about half of the observation days at the OP site the level of ClNO2 increased at sunset but rapidly decreased at around midnight. On the other hand, high levels were sustained throughout the night at the TRF site. Significant levels of ClNO2 were sustained at both sites for 4–5 hours after sunrise. Airborne observations, box model calculations, and back trajectory analysis consistently show that this high levels of ClNO2 in the morning is likely due to the transport of air masses within the boundary layer. Box model results show that chlorine radical initiated chemistry can impact the regional photochemistry by elevating net ozone production rate up to ~ 25 % in the morning.

scholarly journals Characterizing ozone production in the Mexico City Metropolitan Area: a case study using a chemical transport model

2006 ◽  
Vol 6 (4) ◽  
pp. 7959-8009
Author(s):  
W. Lei ◽  
B. de Foy ◽  
M. Zavala ◽  
R. Volkamer ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Metropolitan Area ◽  
Production Efficiency ◽  
Transport Model ◽  
Ozone Production ◽  
Urban Region ◽  
Air Quality Model ◽  
Chemical Transport Model ◽  
Quality Model ◽  
Photochemical Production

Abstract. An episodic simulation is conducted to characterize ozone (O3) photochemical production and investigate its sensitivity to emission changes of ozone precursors in the Mexico City Metropolitan Area (MCMA) using the Comprehensive Air Quality Model with extensions (CAMx). High Ox (O3+NO2) photochemical production rates of 10–80 ppb/h are predicted due to the high reactivity of volatile organic compounds (VOCs) in which alkanes, alkenes, and aromatics exert comparable contributions. The predicted ozone production efficiency is between 4–10 O3 molecules per NOx molecule oxidized, and increases with VOC-to-NO2 reactivity ratio. Process apportionment analyses indicate significant outflow of pollutants such as O3 and peroxyacetyl nitrate (PAN) from the urban area to the surrounding regional environment. PAN is not in chemical-thermal equilibrium during the photochemically active periods. Sensitivity studies of O3 production suggest that O3 formation in the MCMA urban region with less chemical aging (NOz/NOy<0.3) is VOC-limited. Both the simulated behavior of O3 production and its sensitivities to precursors suggest that midday O3 formation during this episode is VOC sensitive in the urban region on the basis of the current emissions inventory. More episodic studies are needed to construct a comprehensive and representative picture of the O3 production characteristics and its response to emission controls.

scholarly journals Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China

2014 ◽  
Vol 14 (5) ◽  
pp. 2419-2429 ◽  
Author(s):  
Y. H. Wang ◽  
B. Hu ◽  
D. S. Ji ◽  
Z. R. Liu ◽  
G. Q. Tang ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Metropolitan Area ◽  
Ozone Concentration ◽  
Production Efficiency ◽  
Aerosol Concentration ◽  
Weekend Effect ◽  
Ozone Production ◽  
Atmospheric Environment ◽  
Meteorological Tower ◽  
Weekly Cycle

Abstract. The ozone weekend effect (OWE) was first investigated in the metropolitan area of Beijing–Tianjin–Hebei (BTH), China, using in situ measurements from the Atmospheric Environment Monitoring Network from July 2009 to August 2011. The results indicate that there is an obvious weekly periodical variation in the surface ozone concentration. There is a lower ozone concentration from Wednesday to Friday (weekday) and a higher concentration from Saturday to Monday (weekend) at all the locations of the study. NOx also displays a weekly cycle, with the maximum level occurring on weekdays and the minimum level on weekends, especially later on Sunday night and early Monday morning. This pattern may be responsible for the higher concentration of ozone on weekends. Additionally, the vertical variations in O3 and NOx from the 8 m, 47 m, 120 m and 280 m observation platforms on the 325 m Beijing meteorological tower displayed obvious weekly cycles that corresponded to the surface results. A smaller decrease in volatile organic compounds (VOCs; using CO as a proxy) and much lower NOx concentrations on the weekend may lead to higher VOC / NOx ratio, which can enhance the ozone production efficiency in VOC-limited regime areas. Additionally, a clear weekly cycle in the fine aerosol concentration was observed, with maximum values occurring on weekdays and minimum values occurring on weekends. Higher concentrations of aerosol on weekdays can reduce the UV radiation flux by scattering or absorbing, which leads to a decrease in the ozone production efficiency. A significant weekly cycle in UV radiation, consistent with the aerosol concentration, was discovered at the Beijing meteorological tower site (BJT), validating the assumption. A comprehensive understanding of the ozone weekend effect in the BTH area can provide deep insights into controlling photochemical pollution.

scholarly journals Factors controlling surface ozone in the Seoul Metropolitan Area during the KORUS-AQ campaign

Elem Sci Anth ◽  
2020 ◽  
Vol 8 ◽  
Author(s):  
Heejeong Kim ◽  
Junsu Gil ◽  
Meehye Lee ◽  
Jinsang Jung ◽  
Andrew Whitehill ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Metropolitan Area ◽  
Production Efficiency ◽  
Surface Ozone ◽  
Sea Breeze ◽  
Photochemical Activity ◽  
Local Circulation ◽  
Boundary Layer Height ◽  
Seoul Metropolitan Area

To understand the characteristics of air quality in the Seoul Metropolitan Area, intensive measurements were conducted under the Korea-United States Air Quality (KORUS-AQ) campaign. Trace gases such as O3, NOx, NOy, SO2, CO, and volatile organic compounds (VOCs), photochemical byproducts such as H2O2 and HCHO, aerosol species, and meteorological variables including planetary boundary layer height were simultaneously measured at Olympic Park in Seoul. During the measurement period, high O3 episodes that exceeded the 90 ppbv hourly maximum occurred on 14 days under four distinct synoptic meteorological conditions. Furthermore, local circulation such as land–sea breeze and diurnal evolution of the boundary layer were crucial in determining the concentrations of precursor gases, including NOx and VOC as well as O3. During such episodes, the nighttime NOx and VOC and daytime UV levels were higher compared to non-episode days. The overall precursor levels and photochemical activity were represented fairly well by variations in the HCHO, which peaked in the morning during the high O3 episodes. This study revealed that toluene was the most abundant VOC in Seoul, and its concentration increased greatly with NOx due to the large local influence under stagnant conditions. When O3 was highly elevated concurrently with PM2.5 under dominant westerlies, NOx and VOCs were relatively lower and CO was noticeably higher than in other episodes. Additionally, the O3 production efficiency was the highest due to a low NOx with the highest NOz/NOy ratio among the four episodes. When westerlies were dominant in transport-south episode, the nighttime concentration of O3 remained as high as 40~50 ppbv due to the minimum level of NOx titration. Overall, the Seoul Metropolitan Area is at NOx-saturated and VOC-limited conditions, which was diagnosed by indicator species and VOC/NOx ratios.

scholarly journals Characterizing ozone production in the Mexico City Metropolitan Area: a case study using a chemical transport model

2007 ◽  
Vol 7 (5) ◽  
pp. 1347-1366 ◽  
Author(s):  
W. Lei ◽  
B. de Foy ◽  
M. Zavala ◽  
R. Volkamer ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Metropolitan Area ◽  
Production Efficiency ◽  
Transport Model ◽  
Ozone Production ◽  
Urban Region ◽  
Air Quality Model ◽  
Chemical Transport Model ◽  
Quality Model ◽  
Photochemical Production

Abstract. An episodic simulation is conducted to characterize midday (12:00–17:00 CDT) ozone (O3) photochemical production and to investigate its sensitivity to emission changes of ozone precursors in the Mexico City Metropolitan Area (MCMA) during an "O3-South" meteorological episode using the Comprehensive Air Quality Model with extensions (CAMx). High Ox (O3+NO2) photochemical production rates of 10–80 ppb/h are predicted due to the high reactivity of volatile organic compounds (VOCs) in which alkanes, alkenes, and aromatics exert comparable contributions. The predicted ozone production efficiency is between 4–10 O3 molecules per NOx molecule oxidized, and increases with VOC-to-NO2 reactivity ratio. Process apportionment analyses indicate significant outflow of pollutants such as O3 and peroxyacetyl nitrate (PAN) from the urban area to the surrounding regional environment. PAN is not in chemical-thermal equilibrium during the photochemically active periods. Sensitivity studies of O3 production suggest that O3 formation in the MCMA urban region with less chemical aging (NOz/NOy<0.3) is VOC-limited. Both the simulated behavior of O3 production and its sensitivities to precursors suggest that midday O3 formation during this episode is VOC-sensitive in the urban region on the basis of the current emissions inventory estimates, and current NOx levels depress the O3 production.

scholarly journals Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China

2013 ◽  
Vol 13 (5) ◽  
pp. 13045-13078 ◽  
Author(s):  
Y. H. Wang ◽  
B. Hu ◽  
Y. S. Wang
Keyword(s):  
Uv Radiation ◽  
Metropolitan Area ◽  
Ozone Concentration ◽  
Production Efficiency ◽  
Aerosol Concentration ◽  
Weekend Effect ◽  
Ozone Production ◽  
Atmospheric Environment ◽  
Entire Study ◽  
Weekly Cycle

Abstract. The ozone weekend effect (OWE) was first investigated in the metropolitan area of Beijing–Tianjin–Hebei (BTH), China, using in situ measurements from the Atmospheric Environment Monitoring Network from July 2009 to August 2011. The results indicate that there is an obvious weekly periodical variation in the surface ozone concentration based on 24 h averaged value. There is a lower ozone concentration from Wednesday to Friday (weekday) and a higher concentration from Saturday to Monday (weekend) over the entire study area. NOx also displays weekly cycle, with the maximum level occurring on weekdays and the minimum level on weekends, especially later on Sunday night and early Monday morning. This pattern may be responsible for the higher concentration of ozone on weekends. Additionally, the vertical variations in O3 and NOx from the 8 m 47 m, 120 m and 280 m observation platforms on the 325 m Beijing meteorological tower displayed obvious weekly cycles that corresponded to the surface results. A smaller decrease in VOCs (a proxy for CO) and much lower NOx concentrations on the weekend may lead to higher VOC/NOx ratio, which can enhance the ozone production efficiency in VOC-regime areas. Additionally, a clear weekly cycle in the fine aerosol concentration was observed, with maximum values occurring on weekdays and minimum values occurring on weekends. Higher concentrations of aerosol on weekdays can reduce the UV radiation flux by absorption or scattering, which leads to a decrease in the ozone production efficiency. A significant weekly cycle in UV radiation, in consistent with the aerosol concentration, was discovered at the BJT site, validating the assumption. A comprehensive understanding of the ozone weekend effect in the BTH area can provide deep insights into controlling photochemical pollution.

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