scholarly journals Ozone Production and Its Sensitivity to NO<sub><i>x</i></sub> and VOCs: Results from the DISCOVER-AQ Field Experiment, Houston 2013

2016 ◽  
Author(s):  
Gina M. Mazzuca ◽  
Xinrong Ren ◽  
Christopher P. Loughner ◽  
Mark Estes ◽  
James H. Crawford ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Production Efficiency ◽  
Photochemical Oxidation ◽  
Ozone Production ◽  
Nox Emissions ◽  
Long Run ◽  
Secondary Air Pollutants ◽  
Secondary Air ◽  
Bond Mechanism

Abstract. An observation-constrained box model based on the Carbon Bond mechanism, Version 5 (CB05), was used to study photochemical processes along the NASA P-3B flight track and spirals over eight surface sites during the September 2013 Houston, Texas deployment of the NASA DISCOVER-AQ campaign. Data from this campaign provided an opportunity to examine and improve our understanding of atmospheric photochemical oxidation processes related to the formation of secondary air pollutants such as ozone (O3). O3 production and its sensitivity to NOx and VOCs were calculated at different locations and times of day. Ozone production efficiency (OPE), defined as the ratio of the ozone production rate to the NOx oxidation rate, was calculated using the observations and the simulation results of the box and Community Multiscale Air Quality (CMAQ) models. Correlations of these results with other parameters, such as radical sources and NOx mixing ratio, were also evaluated. It was generally found that O3 production tends to be more VOC sensitive in the morning along with high ozone production rates, suggesting that control of VOCs may be an effective way to control O3 in Houston. In the afternoon, O3 production was found to be mainly NOx sensitive with some exceptions. O3 production at near major emissions sources such as Deer Park was mostly VOC sensitive for the entire day, other urban areas near Moody Tower and Channelview were VOC sensitive or in the transition regime, and areas farther from downtown Houston such as Smith Point and Conroe were mostly NOx sensitive for the entire day. It was also found that the control of NOx emissions has reduced O3 concentrations over Houston, but led to larger OPE values. The results from this work strengthen our understanding of O3 production; they indicate that controlling NOx emissions will provide air quality benefits over the greater Houston metropolitan area in the long run, but in selected areas controlling VOC emissions will also be beneficial.

scholarly journals Ozone production and its sensitivity to NO<sub><i>x</i></sub> and VOCs: results from the DISCOVER-AQ field experiment, Houston 2013

2016 ◽  
Vol 16 (22) ◽  
pp. 14463-14474 ◽  
Author(s):  
Gina M. Mazzuca ◽  
Xinrong Ren ◽  
Christopher P. Loughner ◽  
Mark Estes ◽  
James H. Crawford ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Production Efficiency ◽  
Photochemical Oxidation ◽  
Ozone Production ◽  
Nox Emissions ◽  
Long Run ◽  
Secondary Air Pollutants ◽  
Secondary Air ◽  
Bond Mechanism

Abstract. An observation-constrained box model based on the Carbon Bond mechanism, version 5 (CB05), was used to study photochemical processes along the NASA P-3B flight track and spirals over eight surface sites during the September 2013 Houston, Texas deployment of the NASA Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign. Data from this campaign provided an opportunity to examine and improve our understanding of atmospheric photochemical oxidation processes related to the formation of secondary air pollutants such as ozone (O3). O3 production and its sensitivity to NOx and volatile organic compounds (VOCs) were calculated at different locations and times of day. Ozone production efficiency (OPE), defined as the ratio of the ozone production rate to the NOx oxidation rate, was calculated using the observations and the simulation results of the box and Community Multiscale Air Quality (CMAQ) models. Correlations of these results with other parameters, such as radical sources and NOx mixing ratio, were also evaluated. It was generally found that O3 production tends to be more VOC-sensitive in the morning along with high ozone production rates, suggesting that control of VOCs may be an effective way to control O3 in Houston. In the afternoon, O3 production was found to be mainly NOx-sensitive with some exceptions. O3 production near major emissions sources such as Deer Park was mostly VOC-sensitive for the entire day, other urban areas near Moody Tower and Channelview were VOC-sensitive or in the transition regime, and areas farther from downtown Houston such as Smith Point and Conroe were mostly NOx-sensitive for the entire day. It was also found that the control of NOx emissions has reduced O3 concentrations over Houston but has led to larger OPE values. The results from this work strengthen our understanding of O3 production; they indicate that controlling NOx emissions will provide air quality benefits over the greater Houston metropolitan area in the long run, but in selected areas controlling VOC emissions will also be beneficial.

scholarly journals Modelling the impact of megacities on local, regional and global tropospheric ozone and the deposition of nitrogen species

2013 ◽  
Vol 13 (24) ◽  
pp. 12215-12231 ◽  
Author(s):  
Z. S. Stock ◽  
M. R. Russo ◽  
T. M. Butler ◽  
A. T. Archibald ◽  
M. G. Lawrence ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Climate Model ◽  
Surface Ozone ◽  
Global Scale ◽  
Chemical Environment ◽  
Ozone Production ◽  
The Uk ◽  
The Impact ◽  
Local Emissions

Abstract. We examine the effects of ozone precursor emissions from megacities on present-day air quality using the global chemistry–climate model UM-UKCA (UK Met Office Unified Model coupled to the UK Chemistry and Aerosols model). The sensitivity of megacity and regional ozone to local emissions, both from within the megacity and from surrounding regions, is important for determining air quality across many scales, which in turn is key for reducing human exposure to high levels of pollutants. We use two methods, perturbation and tagging, to quantify the impact of megacity emissions on global ozone. We also completely redistribute the anthropogenic emissions from megacities, to compare changes in local air quality going from centralised, densely populated megacities to decentralised, lower density urban areas. Focus is placed not only on how changes to megacity emissions affect regional and global NOx and O3, but also on changes to NOy deposition and to local chemical environments which are perturbed by the emission changes. The perturbation and tagging methods show broadly similar megacity impacts on total ozone, with the perturbation method underestimating the contribution partially because it perturbs the background chemical environment. The total redistribution of megacity emissions locally shifts the chemical environment towards more NOx-limited conditions in the megacities, which is more conducive to ozone production, and monthly mean surface ozone is found to increase up to 30% in megacities, depending on latitude and season. However, the displacement of emissions has little effect on the global annual ozone burden (0.12% change). Globally, megacity emissions are shown to contribute ~3% of total NOy deposition. The changes in O3, NOx and NOy deposition described here are useful for quantifying megacity impacts and for understanding the sensitivity of megacity regions to local emissions. The small global effects of the 100% redistribution carried out in this study suggest that the distribution of emissions on the local scale is unlikely to have large implications for chemistry–climate processes on the global scale.

scholarly journals Impact of a new condensed toluene mechanism on air quality model predictions in the US

2010 ◽  
Vol 3 (4) ◽  
pp. 2291-2314
Author(s):  
G. Sarwar ◽  
K. W. Appel ◽  
A. G. Carlton ◽  
R. Mathur ◽  
K. Schere ◽  
...  
Keyword(s):  
Air Quality ◽  
Los Angeles ◽  
Production Efficiency ◽  
Sensitivity Study ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Daily Maximum ◽  
Air Quality Model ◽  
Quality Model ◽  
Mixing Ratios

Abstract. A new condensed toluene mechanism is incorporated into the Community Multiscale Air Quality Modeling system. Model simulations are performed using the CB05 chemical mechanism containing the existing (base) and the new toluene mechanism for the western and eastern US for a summer month. With current estimates of tropospheric emission burden, the new toluene mechanism increases monthly mean daily maximum 8-h ozone by 1.0–3.0 ppbv in Los Angeles, Portland, Seattle, Chicago, Cleveland, northeastern US, and Detroit compared to that with the base toluene chemistry. It reduces model mean bias for ozone at elevated observed ozone mixing ratios. While the new mechanism increases predicted ozone, it does not enhance ozone production efficiency. Sensitivity study suggests that it can further enhance ozone if elevated toluene emissions are present. While changes in total fine particulate mass are small, predictions of in-cloud SOA increase substantially.

Ozone Photochemistry in New York City and Baltimore based on Aircraft Observations

2021 ◽  
Author(s):  
Xinrong Ren ◽  
Phillip Stratton ◽  
Hannah Daley ◽  
Russell Dickerson
Keyword(s):  
New York ◽  
New York City ◽  
York City ◽  
Production Efficiency ◽  
Control Strategies ◽  
Scientific Information ◽  
Photochemical Oxidation ◽  
Ozone Production ◽  
Source Regions ◽  
Aircraft Observations

&lt;p&gt;Aircraft observations of ozone, ozone precursors, and meteorological parameters were made over the New York City (NYC) and Baltimore areas during ozone exceedance events in summer 2018-2020.&amp;#160; Despite the continued reduction in anthropogenic emissions, ozone exceedance events still frequently occurred in the NYC area.&amp;#160; Ozone production efficiency, defined as the ratio of the ozone production rate to the NO&lt;sub&gt;x&lt;/sub&gt; oxidation rate, calculated using these observations,&amp;#160; was about 14 ppb ozone produced per ppb NOx oxidized. This high ozone production efficiency likely contributes to the persistent ozone exceedance problem over the Long Island Sound and Connecticut coastal area, downwind of NYC under prevailing southwesterly winds.&amp;#160; There is some evidence for a decreasing trend although COVID-19 restrictions had an impact on 2020 emissions.&amp;#160; A box model, constrained by observations, was used to examine atmospheric photochemical oxidation processes.&amp;#160; Ozone production rates and their sensitivity to nitrogen oxides (NO&lt;sub&gt;x&lt;/sub&gt;) and volatile organic compounds (VOCs) were calculated based on the model results. In general ozone production is VOC sensitive near emission sources and NOx sensitive away from source regions. While the Baltimore area is predominantly in the NOx sensitive region, the NYC area is transitioning from VOC sensitive to NOx sensitive.&amp;#160; Preliminary results show that controlling both NOx and VOCs reduces ozone production in the NYC area. Reducing VOCs can reduce ozone production in emission source regions and reducing NOx can reduce ozone production farther away from the source regions. The results from this work strengthen our understanding of ozone production and provide scientific information for emission control strategies to reduce air pollution in ozone non-attainment areas.&lt;/p&gt;

scholarly journals Eta-CMAQ air quality forecasts for O<sub>3</sub> and related species using three different photochemical mechanisms (CB4, CB05, SAPRC-99): comparisons with measurements during the 2004 ICARTT study

2010 ◽  
Vol 10 (6) ◽  
pp. 3001-3025 ◽  
Author(s):  
S. Yu ◽  
R. Mathur ◽  
G. Sarwar ◽  
D. Kang ◽  
D. Tong ◽  
...  
Keyword(s):  
Air Quality ◽  
Production Efficiency ◽  
Gulf Of Maine ◽  
Ozone Production ◽  
Eastern United States ◽  
Forecast Performance ◽  
Transport And Transformation ◽  
Mixing Ratios ◽  
Upper Limits ◽  
The Impact

Abstract. A critical module of air quality models is the photochemical mechanism. In this study, the impact of the three photochemical mechanisms (CB4, CB05, SAPRC-99) on the Eta-Community Multiscale Air Quality (CMAQ) model's forecast performance for O3, and its related precursors has been assessed over the eastern United States with observations obtained by aircraft (NOAA P-3 and NASA DC-8) flights, ship and two surface networks (AIRNow and AIRMAP) during the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) study. The results show that overall none of the mechanisms performs systematically better than the others. On the other hand, at the AIRNow surface sites, CB05 has the best performance with the normalized mean bias (NMB) of 3.9%, followed by CB4 (NMB=−5.7%) and SAPRC-99 (NMB=10.6%) for observed O3≥75 ppb, whereas CB4 has the best performance with the least overestimation for observed O3<75 ppb. On the basis of comparisons with aircraft P-3 measurements, there were consistent overestimations of O3, NOz, PAN and NOy and consistent underestimations of CO, HNO3, NO2, NO, SO2 and terpenes for all three mechanisms although the NMB values for each species and mechanisms were different. The results of aircraft DC-8 show that CB05 predicts the H2O2 mixing ratios most closely to the observations (NMB=10.8%), whereas CB4 and SAPRC-99 overestimated (NMB=74.7%) and underestimated (NMB=−25.5%) H2O2 mixing ratios significantly, respectively. For different air mass flows over the Gulf of Maine on the basis of the ship data, the three mechanisms have relatively better performance for O3, isoprene and SO2 for the clean marine or continental flows but relatively better performance for CO, NO2 and NO for southwesterly/westerly offshore flows. The results of the O3-NOz slopes over the ocean indicate that SAPRC-99 has the highest upper limits of the ozone production efficiency (εN) (5.8), followed by CB05 (4.5) and CB4 (4.0) although they are much lower than that inferred from the observation (11.8), being consistent with the fact that on average, SAPRC-99 produces the highest O3, followed by CB05 and CB4, across all O3 mixing ratio ranges

scholarly journals Sensitivities of NO<sub>x</sub> transformation and the effects on surface ozone and nitrate

2014 ◽  
Vol 14 (3) ◽  
pp. 1385-1396 ◽  
Author(s):  
H. Lei ◽  
J. X. L. Wang
Keyword(s):  
Air Quality ◽  
Los Angeles ◽  
Surface Ozone ◽  
Nox Emission ◽  
Ozone Production ◽  
Limited Area ◽  
Transformation Rate ◽  
Nox Emissions ◽  
Increase Rate ◽  
Industrial Regions

Abstract. As precursors to tropospheric ozone and nitrate, nitrogen oxide (NOx) in the present atmosphere and its transformation in response to emission and climate perturbations are studied by using the CAM-Chem model and air quality measurements from the National Emissions Inventory (NEI), Clean Air Status and Trends Network (CASTNET), and Environmental Protection Agency Air Quality System (EPA AQS). It is found that NOx transformations in present atmospheric conditions show different sensitivities over industrial and non-industrial regions. As a result, the surface ozone and nitrate formations can be divided into several regimes associated with the dominant emission types and relative levels of NOx and volatile organic compounds (VOC). Ozone production in industrial regions (the main NOx emission source areas) increases in warmer conditions and slightly decreases following an increase in NOx emissions due to NOx titration, which is opposite to the response in non-industrial regions. The ozone decrease following a temperature increase in non-industrial regions indicates that ozone production in regions that lack NOx emission sources may be sensitive to NOx transformation in remote source regions. The increase in NO2 from NOx titration over industrial regions results in an increase rate of total nitrate that remains higher than the increase rate of NOx emissions. The presented findings indicate that a change in the ozone concentration is more directly affected by changes in climate and precursor emissions, while a change in the nitrate concentration is affected by local ozone production types and their seasonal transfer. The sensitivity to temperature perturbations shows that a warmer climate accelerates the decomposition of odd nitrogen (NOy) during the night. As a result, the transformation rate of NOx to nitrate decreases. Examinations of the historical emissions and air quality records of a typical NOx-limited area, such as Atlanta and a VOC-limited area, such as Los Angeles further confirm the conclusions drawn from the modeling experiments.

scholarly journals Impact of a new condensed toluene mechanism on air quality model predictions in the US

2011 ◽  
Vol 4 (1) ◽  
pp. 183-193 ◽  
Author(s):  
G. Sarwar ◽  
K. W. Appel ◽  
A. G. Carlton ◽  
R. Mathur ◽  
K. Schere ◽  
...  
Keyword(s):  
Air Quality ◽  
Los Angeles ◽  
Production Efficiency ◽  
Sensitivity Study ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Daily Maximum ◽  
Air Quality Model ◽  
Quality Model ◽  
The Us

Abstract. A new condensed toluene mechanism is incorporated into the Community Multiscale Air Quality Modeling system. Model simulations are performed using the CB05 chemical mechanism containing the existing (base) and the new toluene mechanism for the western and eastern US for a summer month. With current estimates of tropospheric emission burden, the new toluene mechanism increases monthly mean daily maximum 8-h ozone by 1.0–3.0 ppbv in Los Angeles, Portland, Seattle, Chicago, Cleveland, northeastern US, and Detroit compared to that with the base toluene chemistry. It reduces model mean bias for ozone at elevated observed ozone concentrations. While the new mechanism increases predicted ozone, it does not enhance ozone production efficiency. A sensitivity study suggests that it can further enhance ozone if elevated toluene emissions are present. While it increases in-cloud secondary organic aerosol substantially, its impact on total fine particle mass concentration is small.

scholarly journals Slower ozone production in Houston, Texas following emission reductions: evidence from Texas Air Quality Studies in 2000 and 2006

2014 ◽  
Vol 14 (6) ◽  
pp. 2777-2788 ◽  
Author(s):  
W. Zhou ◽  
D. S. Cohan ◽  
B. H. Henderson
Keyword(s):  
Air Quality ◽  
Production Efficiency ◽  
Ozone Production ◽  
Ozone Formation ◽  
Airborne Measurements ◽  
Chemical Complexity ◽  
Balanced Approach ◽  
Radical Production ◽  
Field Campaigns ◽  
Houston Area

Abstract. Airborne measurements from two Texas Air Quality Study (TexAQS) field campaigns have been used to investigate changes of ozone production in Houston, Texas, from 2000 to 2006, a period of major emission reduction measures for petrochemical and other sources. Simultaneous declines in nitrogen oxides (NOx = NO + NO2) and highly reactive volatile organic compounds (HRVOCs) were observed between the two periods. We simulate HOx (OH and HO2) and organic radicals with a box model, the Dynamically Simple Model of Atmospheric Chemical Complexity, constrained by available airborne observations. Parameters such as total radical production, total OH reactivity of VOCs and ozone production rate (OPR) are computed to characterize the change of ozone production between 2000 and 2006 in the Houston area. The reduction in HRVOCs led to a decline in total radical production by 20–50%. Ozone production rates in the Houston area declined by 40–50% from 2000 to 2006, to which the reduction in NOx and HRVOCs made large contributions. Despite the significant decline in OPR, ozone production efficiency held steady, and VOC-sensitive conditions dominated during times of most rapid ozone formation, while the slow ozone formation continued to be NOx-limited. Our results highlight the importance of a balanced approach of ongoing HRVOC controls with NOx controls to further reduce O3 levels in the Houston area.

scholarly journals Slower ozone production in Houston, Texas following emission reductions: evidence from Texas Air Quality Studies in 2000 and 2006

2013 ◽  
Vol 13 (7) ◽  
pp. 19085-19120 ◽  
Author(s):  
W. Zhou ◽  
D. S. Cohan ◽  
B. H. Henderson
Keyword(s):  
Air Quality ◽  
Production Efficiency ◽  
Organic Radicals ◽  
Ozone Production ◽  
Airborne Measurements ◽  
Chemical Complexity ◽  
Radical Production ◽  
Volatile Organic ◽  
Field Campaigns ◽  
Houston Area

Abstract. Airborne measurements from two Texas Air Quality Study (TexAQS) field campaigns have been used to investigate changes of ozone production in Houston, Texas, from 2000 to 2006, a period of major emission reduction measures at petrochemical and other sources. Simultaneous declines in nitrogen oxides (NOx=NO+NO2) and highly reactive volatile organic compounds (HRVOCs) were observed between the two periods. We simulated HOx (OH and HO2) and organic radicals with a box model, the Dynamically Simple Model of Atmospheric Chemical Complexity, constrained by available airborne observations. Parameters such as total radical production, total OH reactivity of VOCs and ozone production rate (P(O3) are computed to characterize the change of ozone production between 2000 and 2006 in the Houston area. The reduction in HRVOCs led to a decline in total radical production by 20–50%. Ozone production rates in the Houston area declined by 40–50% from 2000 to 2006, to which the reduction in NOx and HRVOCs had large contributions. Despite the significant decline in P(O3), ozone production efficiency held steady, and VOC-sensitive conditions dominated during times of most rapid ozone formation. Our results highlight the importance of ongoing HRVOC controls to further reduce O3 levels in the Houston area.

scholarly journals Impact of Mexico City emissions on regional air quality from MOZART-4 simulations

2010 ◽  
Vol 10 (2) ◽  
pp. 3457-3498 ◽  
Author(s):  
L. K. Emmons ◽  
E. C. Apel ◽  
J.-F. Lamarque ◽  
P. G. Hess ◽  
M. Avery ◽  
...  
Keyword(s):  
Air Quality ◽  
Mexico City ◽  
Production Efficiency ◽  
Transport Model ◽  
Ozone Production ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Model Calculations ◽  
Fire Emissions ◽  
Regional Air Quality

Abstract. An extensive set of measurements was made in and around Mexico City as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) experiments in March 2006. Simulations with the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4), a global chemical transport model, have been used to provide a regional context for these observations and assist in their interpretation. These MOZART-4 simulations reproduce the aircraft observations generally well, but some differences in the modeled volatile organic compounds (VOCs) from the observations result from incorrect VOC speciation assumed for the emission inventories. The different types of CO sources represented in the model have been "tagged" to quantify the contributions of regions outside Mexico, as well as the various emissions sectors within Mexico, to the regional air quality of Mexico. This analysis indicates open fires have some, but not a dominant, impact on the atmospheric composition in the region around Mexico City, when averaged over the month. However, considerable variation in the fire contribution (2–15% of total CO) is seen during the month. The transport and photochemical aging of Mexico City emissions were studied using tags of CO emissions for each day, showing that typically the air near Mexico City was a combination of many ages. Ozone production in MOZART-4 is shown to agree well with the net production rates from box model calculations constrained by the MILAGRO aircraft measurements. Ozone production efficiency derived from the ratio of Ox to NOz is higher in MOZART-4 than in the observations for moderately polluted air. OH reactivity determined from the MOZART-4 results shows the same increase in relative importance of oxygenated VOCs downwind of Mexico City as the reactivity inferred from the observations. The amount of ozone produced by emissions from Mexico City and surrounding areas has been quantified in the model by tracking NO emissions, showing little influence beyond Mexico's borders, and also relatively minor influence from fire emissions on the monthly average tropospheric ozone column.

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