scholarly journals Investigate Wildfire Impacts on Ozone Production by Vertical Observations and Photochemical Modeling

2020 ◽  
Vol 237 ◽  
pp. 03014
Author(s):  
Bo Wang ◽  
Michael Newchurch ◽  
Shi Kuang ◽  
Arastoo Biazar
Keyword(s):  
Boundary Layer ◽  
Biomass Burning ◽  
Surface Ozone ◽  
Ozone Production ◽  
Ozone Precursors ◽  
Photochemical Modeling ◽  
Enhanced Surface ◽  
Troposphere Ozone ◽  
Effective Integration ◽  
Aerosol Plume

In troposphere, ozone is a toxic secondary pollutant produced when its precursors react in sunlight. An important source of ozone precursors is biomass burning. Here we investigate the impacts of 2016 Southeast U.S. Wildfires on ozone production by integrating vertical resolved ozone profiles and photochemical modeling. The results show that wildfires contributed to ozone lamina at the top of boundary layer and enhanced surface ozone up to about 10ppbv in Southeast U.S.. Ozone lidar observed a lower ozone change with respect to a fast growth of aerosol plume, of which the reason is also investigated. Current results indicate an effective integration of vertical observations and modeling for us to understand the ozone production from fires in troposphere.

scholarly journals Simulations over South Asia using the weather research and forecasting model with chemistry (WRF-Chem): chemistry evaluation and initial results

2012 ◽  
Vol 5 (1) ◽  
pp. 1-66 ◽  
Author(s):  
R. Kumar ◽  
M. Naja ◽  
G. G. Pfister ◽  
M. C. Barth ◽  
C. Wiedinmyer ◽  
...  
Keyword(s):  
South Asia ◽  
Biomass Burning ◽  
Surface Ozone ◽  
Ozone Production ◽  
Weather Research And Forecasting ◽  
Northern India ◽  
Vertical Distributions ◽  
Spatio Temporal ◽  
First Time ◽  
Vertical Ozone

Abstract. This study presents annual simulations of tropospheric ozone and related species made for the first time using the WRF-Chem model over South Asia for the year 2008. The model simulated ozone, CO, and NOx are evaluated against ground-based, balloon-borne and satellite-borne (TES, OMI and MOPITT) observations. The comparison of model results with surface ozone observations from seven sites and CO and NOx observations from three sites, indicate the model's ability in reproducing seasonal variations of ozone and CO, but show some differences in NOx. The modeled vertical ozone distribution agrees well with the ozone soundings data from two Indian sites. The vertical distributions of TES ozone and MOPITT CO are generally well reproduced, but the model underestimates TES ozone, OMI tropospheric column NO2 and MOPITT total column CO retrievals during all the months except MOPITT retrievals during August–January. Largest differences between modeled and satellite retrieved quantities are found during spring when intense biomass burning activity occurs in this region. The evaluation results indicate large uncertainties in anthropogenic and biomass burning emission estimates, especially for NOx. The model results indicate clear regional differences in the seasonality of surface ozone over South Asia with estimated net ozone production during daytime (11:30–15:30 h) over inland regions of 0–5 ppbv h−1 during all seasons and of 0–2 ppbv h−1 over marine regions during outflow periods. The model results indicate that ozone production in this region is mostly NOx-limited. This study shows that WRF-Chem model captures many important features of the observations and gives confidence to using the model for understanding the spatio-temporal variability of ozone over South Asia. However, improvements of South Asian emission inventories and simulations at finer model resolution, especially over the complex Himalayan terrain in Northern India, are also essential for accurately simulating ozone in this region.

scholarly journals The influence of European pollution on ozone in the Near East and northern Africa

2008 ◽  
Vol 8 (1) ◽  
pp. 1913-1950 ◽  
Author(s):  
B. N. Duncan ◽  
J. J. West ◽  
Y. Yoshida ◽  
A. M. Fiore ◽  
J. R. Ziemke
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Near East ◽  
Surface Ozone ◽  
Northern Africa ◽  
Ozone Production ◽  
Ozone Pollution ◽  
East European ◽  
European Health ◽  
Ozone Precursor

Abstract. We present a modeling study of the long-range transport of pollution from Europe, showing that European emissions regularly elevate surface ozone by as much as 20 ppbv in summer in northern Africa and the Near East. European emissions cause 50–150 additional violations per year (i.e., above those that would occur without European pollution) of the European health standard for ozone (8-h average >120 μg/m3 or ~60 ppbv) in northern Africa and the Near East. We estimate that 19 000 additional mortalities occur annually in these regions from exposure to European ozone pollution and 50 000 additional deaths globally; the majority of the additional deaths occurs outside of Europe. Much of the pollution from Europe is exported southward at low altitudes in summer to the Mediterranean Sea, northern Africa and the Near East, regions with favorable photochemical environments for ozone production. Our results suggest that assessments of the human health benefits of reducing ozone precursor emissions in Europe should include effects outside of Europe, and that comprehensive planning to improve air quality in northern Africa and the Near East likely needs to address European emissions. We also show that the tropospheric ozone column data product derived from the OMI and MLS instruments is currently of limited value for air quality applications as the portion of the column above the boundary layer and below the tropopause is large and variable, effectively obscuring the boundary layer signal.

scholarly journals Simulations over South Asia using the Weather Research and Forecasting model with Chemistry (WRF-Chem): chemistry evaluation and initial results

2012 ◽  
Vol 5 (3) ◽  
pp. 619-648 ◽  
Author(s):  
R. Kumar ◽  
M. Naja ◽  
G. G. Pfister ◽  
M. C. Barth ◽  
C. Wiedinmyer ◽  
...  
Keyword(s):  
South Asia ◽  
Biomass Burning ◽  
Surface Ozone ◽  
Ozone Production ◽  
Weather Research And Forecasting ◽  
Northern India ◽  
Vertical Distributions ◽  
Spatio Temporal ◽  
First Time ◽  
Vertical Ozone

Abstract. This study presents annual simulations of tropospheric ozone and related species made for the first time using the WRF-Chem model over South Asia for the year 2008. The model-simulated ozone, CO, and NOx are evaluated against ground-based, balloon-borne and satellite-borne (TES, OMI and MOPITT) observations. The comparison of model results with surface ozone observations from seven sites and CO and NOx observations from three sites indicate the model's ability in reproducing seasonal variations of ozone and CO, but show some differences in NOx. The modeled vertical ozone distribution agrees well with the ozone soundings data from two Indian sites. The vertical distributions of TES ozone and MOPITT CO are generally well reproduced, but the model underestimates TES ozone, OMI tropospheric column NO2 and MOPITT total column CO retrievals during all the months, except MOPITT retrievals during August–January and OMI retrievals during winter. Largest differences between modeled and satellite-retrieved quantities are found during spring when intense biomass burning activity occurs in this region. The evaluation results indicate large uncertainties in anthropogenic and biomass burning emission estimates, especially for NOx. The model results indicate clear regional differences in the seasonality of surface ozone over South Asia, with estimated net ozone production during daytime (1130–1530 h) over inland regions of 0–5 ppbv h−1 during all seasons and of 0–2 ppbv h−1 over marine regions during outflow periods. The model results indicate that ozone production in this region is mostly NOx-limited. This study shows that WRF-Chem model captures many important features of the observations and gives confidence to using the model for understanding the spatio-temporal variability of ozone over South Asia. However, improvements of South Asian emission inventories and simulations at finer model resolution, especially over the complex Himalayan terrain in northern India, are also essential for accurately simulating ozone in this region.

scholarly journals Modelling the impact of possible snowpack emissions of O(3P) and NO2 on photochemistry in the South Pole boundary layer

2008 ◽  
Vol 5 (4) ◽  
pp. 268 ◽  
Author(s):  
P. D. Hamer ◽  
D. E. Shallcross ◽  
A. Yabushita ◽  
M. Kawasaki
Keyword(s):  
Climate Change ◽  
Boundary Layer ◽  
Physical Phenomenon ◽  
Surface Ozone ◽  
Ozone Production ◽  
South Pole ◽  
The South ◽  
Photochemical Pollution ◽  
Ozone Concentrations ◽  
The Impact

Environmental context. The study of surface photochemical ozone production on the Antarctic continent has direct relevance to climate change and general air quality and is scientifically noteworthy given the otherwise pristine nature of this environmental region. The identification of possible direct ozone emissions from snow surfaces and their contribution to the already active photochemical pollution present there represents a unique physical phenomenon. This process could have wider global significance for other snow-covered regions and therefore for global climate change. Abstract. O(3P) emissions due to photolysis of nitrate were recently identified from ice surfaces doped with nitric acid. O(3P) atoms react directly with molecular oxygen to yield ozone. Therefore, these results may have direct bearing on photochemical activity monitored at the South Pole, a site already noted for elevated summertime surface ozone concentrations. NO2 is also produced via the photolysis of nitrate and the firn air contains elevated levels of NO2, which will lead to direct emission of NO2. A photochemical box model was used to probe what effect O(3P) and NO2 emissions have on ozone concentrations within the South Pole boundary layer. The results suggest that these emissions could account for a portion of the observed ozone production at the South Pole and may explain the observed upward fluxes of ozone identified there.

scholarly journals Why do models overestimate surface ozone in the Southeast United States?

2016 ◽  
Vol 16 (21) ◽  
pp. 13561-13577 ◽  
Author(s):  
Katherine R. Travis ◽  
Daniel J. Jacob ◽  
Jenny A. Fisher ◽  
Patrick S. Kim ◽  
Eloise A. Marais ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Production Efficiency ◽  
Surface Ozone ◽  
Satellite Observations ◽  
Oxidation Products ◽  
Ozone Production ◽  
Large Contribution ◽  
Nox Emissions ◽  
Tropospheric No2 ◽  
Southeast Us

Abstract. Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx  ≡  NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25°  ×  0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NOx from the US Environmental Protection Agency (EPA) is too high. This finding is based on SEAC4RS observations of NOx and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Our results indicate that NEI NOx emissions from mobile and industrial sources must be reduced by 30–60 %, dependent on the assumption of the contribution by soil NOx emissions. Upper-tropospheric NO2 from lightning makes a large contribution to satellite observations of tropospheric NO2 that must be accounted for when using these data to estimate surface NOx emissions. We find that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 6 ± 14 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease from 1.5 km to the surface that GEOS-Chem does not capture. This bias may reflect a combination of excessive vertical mixing and net ozone production in the model boundary layer.

scholarly journals Large contribution of biomass burning emissions to ozone throughout the global remote troposphere

2021 ◽  
Vol 118 (52) ◽  
pp. e2109628118
Author(s):  
Ilann Bourgeois ◽  
Jeff Peischl ◽  
J. Andrew Neuman ◽  
Steven S. Brown ◽  
Chelsea R. Thompson ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Global Scale ◽  
Ozone Production ◽  
Large Contribution ◽  
Airborne Measurements ◽  
Ozone Precursors ◽  
Remote Troposphere ◽  
Urban Emissions

Ozone is the third most important anthropogenic greenhouse gas after carbon dioxide and methane but has a larger uncertainty in its radiative forcing, in part because of uncertainty in the source characteristics of ozone precursors, nitrogen oxides, and volatile organic carbon that directly affect ozone formation chemistry. Tropospheric ozone also negatively affects human and ecosystem health. Biomass burning (BB) and urban emissions are significant but uncertain sources of ozone precursors. Here, we report global-scale, in situ airborne measurements of ozone and precursor source tracers from the NASA Atmospheric Tomography mission. Measurements from the remote troposphere showed that tropospheric ozone is regularly enhanced above background in polluted air masses in all regions of the globe. Ozone enhancements in air with high BB and urban emission tracers (2.1 to 23.8 ppbv [parts per billion by volume]) were generally similar to those in BB-influenced air (2.2 to 21.0 ppbv) but larger than those in urban-influenced air (−7.7 to 6.9 ppbv). Ozone attributed to BB was 2 to 10 times higher than that from urban sources in the Southern Hemisphere and the tropical Atlantic and roughly equal to that from urban sources in the Northern Hemisphere and the tropical Pacific. Three independent global chemical transport models systematically underpredict the observed influence of BB on tropospheric ozone. Potential reasons include uncertainties in modeled BB injection heights and emission inventories, export efficiency of BB emissions to the free troposphere, and chemical mechanisms of ozone production in smoke. Accurately accounting for intermittent but large and widespread BB emissions is required to understand the global tropospheric ozone burden.

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.

30 years of surface ozone measurements in Austria: long-term trends, attainment statistics, and changes in the temperature sensitivity of surface ozone production

2021 ◽  
Author(s):  
Christoph Stähle ◽  
Monika Mayer ◽  
Christian Schmidt ◽  
Jessica Kult ◽  
Vinzent Klaus ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Surface Ozone ◽  
Global Radiation ◽  
Mixing Layer ◽  
Ozone Production ◽  
Daily Minimum Temperature ◽  
Monitoring Networks ◽  
Seasonal Basis ◽  
Minimum Daily Temperature ◽  
The Impact

<p>As the production of ozone in surface air is determined by ambient temperature and by the prevalent chemical regime, a very different temperature dependence of ozone production emerges for nitrogen oxides (NO<sub>x</sub>) and volatile organic compounds (VOC) limited regions. In this study we evaluated the temperature sensitivity of ozone production for rural, suburban as well as urban sites in Austria on seasonal basis. The analysis is based on 30 years of observational data from Austrian monitoring networks for the time period 1990 – 2019. Reductions in precursor emissions as observed in 2020 in Austria due to the pandemic will be used to test the obtained results. Surface ozone, NO<sub>x</sub>, daily sums of global radiation and minimum daily temperature are used as covariates in our study. The observed NO<sub>x</sub> to VOC ratio at individual sites is variable over time due to changes in precursor emissions and/or the variability of meteorological parameters such as mixing layer height. At the site level we relate the temperature sensitivity of ozone production to the daily mean NO<sub>x</sub> mixing ratio and the daily minimum temperature. This information allows us to determine the impact of past/future temperature changes on surface ozone abundance in the context of reductions of NO<sub>x</sub> emissions and changing methane backgrounds.</p>

scholarly journals Variations in O<sub>3</sub>, CO, and CH<sub>4</sub> over the Bay of Bengal during the summer monsoon season: Ship-borne measurements and model simulations

2016 ◽  
Author(s):  
Imran A. Girach ◽  
Narendra Ojha ◽  
Prabha R. Nair ◽  
Andrea Pozzer ◽  
Yogesh K. Tiwari ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Bay Of Bengal ◽  
Monsoon Season ◽  
Surface Ozone ◽  
Ozone Production ◽  
Spatial And Temporal Variability ◽  
Summer Monsoon Season ◽  
Rainfall Events ◽  
Model Simulations ◽  
Mixing Ratios

Abstract. We present ship-borne measurements of surface ozone, carbon monoxide and methane over the Bay of Bengal (BoB), the first time such measurements have been taken during the summer monsoon season, as a part of the Continental Tropical Convergence Zone (CTCZ) experiment during 2009. O3, CO, and CH4 mixing ratios exhibited significant spatial and temporal variability in the ranges of 8–54 nmol mol−1, 50–200 nmol mol−1, and 1.57–2.15 µmol mol−1, with means of 29.7 ± 6.8 nmol mol−1, 96 ± 25 nmol mol−1, and 1.83 ± 0.14 µmol mol−1, respectively. The average mixing ratios of trace gases over northern BoB (O3: 30 ± 7 nmol mol−1, CO: 95 ± 25 nmol mol−1, CH4: 1.86 ± 0.12 µmol mol−1), in airmasses from northern or central India, did not differ much from those over central BoB (O3: 27 ± 5 nmol mol−1, CO: 101 ± 27 nmol mol−1, CH4: 1.72 ± 0.14 µmol mol−1), in airmasses from southern India. Spatial variability is observed to be most significant for CH4. The ship-based observations, in conjunction with backward air trajectories and ground-based measurements over the Indian region, are analyzed to estimate a net ozone production of 1.5–4 nmol mol−1 day−1 in the outflow. Ozone mixing ratios over the BoB showed large reductions (by ~ 20 nmol mol−1) during four rainfall events. Temporal changes in the meteorological parameters, in conjunction with ozone vertical profiles, indicate that these low ozone events are associated with downdrafts of free-tropospheric ozone-poor airmasses. While the observed variations in O3 and CO are successfully reproduced using the Weather Research and Forecasting model with Chemistry (WRF-Chem), this model overestimates mean concentrations by about 20 %, generally overestimating O3 mixing ratios during the rainfall events. Analysis of the chemical tendencies from model simulations for a low-O3 event on August 10, 2009, captured successfully by the model, shows the key role of horizontal advection in rapidly transporting ozone-rich airmasses across the BoB. Our study fills a gap in the availability of trace gas measurements over the BoB, and when combined with data from previous campaigns, reveals large seasonal amplitude (~ 39 and ~ 207 nmol mol−1 for O3 and CO, respectively) over the northern BoB.

scholarly journals Analysis of the latitudinal variability of tropospheric ozone in the Arctic using the large number of aircraft and ozonesonde observations in early summer 2008

2016 ◽  
Author(s):  
Gerard Ancellet ◽  
Nikos Daskalakis ◽  
Jean Christophe Raut ◽  
Boris Quennehen ◽  
François Ravetta ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Tropospheric Ozone ◽  
Lower Troposphere ◽  
Early Summer ◽  
Ozone Production ◽  
The Arctic ◽  
Integrated Analysis ◽  
International Polar Year ◽  
Latitude Range ◽  
Vertical Variability

Abstract. The goal of the paper are to: (1) present tropospheric ozone (O3) climatologies in summer 2008 based on a large amount of measurements, during the International Polar Year when the Polar Study using Aircraft, Remote Sensing, Surface Measurements, and Models of Climate Chemistry, Aerosols, and Transport (POLARCAT) campaigns were conducted (2) investigate the processes that determine O3 concentrations in two different regions (Canada and Greenland) that were thoroughly studied using measurements from 3 aircraft and 7 ozonesonde stations. This paper provides an integrated analysis of these observations and the discussion of the latitudinal and vertical variability of tropospheric ozone north of 55° N during this period is performed using a regional model (WFR-Chem). Ozone, CO and potential vorticity (PV) distributions are extracted from the simulation at the measurement locations. The model is able to reproduce the O3 latitudinal and vertical variability but a negative O3 bias of 6–15 ppbv is found in the free troposphere over 4 km, especially over Canada. Ozone average concentrations are of the order of 65 ppbv at altitudes above 4 km both over Canada and Greenland, while they are less than 50 ppbv in the lower troposphere. The relative influence of stratosphere-troposphere exchange (STE) and of ozone production related to the local biomass burning (BB) emissions is discussed using differences between average values of O3, CO and PV for Southern and Northern Canada or Greenland and two vertical ranges in the troposphere: 0–4 km and 4–8 km. For Canada, the model CO distribution and the weak correlation (< 30 %) of O3 and PV suggests that stratosphere-troposphere exchange (STE) is not the major contribution to average tropospheric ozone at latitudes less than 70° N, due to the fact that local biomass burning (BB) emissions were significant during the 2008 summer period. Conversely over Greenland, significant STE is found according to the better O3 versus PV correlation (> 40 %) and the higher 75th PV percentile. A weak negative latitudinal summer ozone gradient −6 to −8 ppbv is found over Canada in the mid troposphere between 4 and 8 km. This is attributed to an efficient O3 photochemical production due to the BB emissions at latitudes less than 65° N, while STE contribution is more homogeneous in the latitude range 55° N to 70° N. A positive ozone latitudinal gradient of 12 ppbv is observed in the same altitude range over Greenland not because of an increasing latitudinal influence of STE, but because of different long range transport from multiple mid-latitude sources (North America, Europe and even Asia for latitudes higher than 77° N).

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