Effects of trans-Eurasian transport of air pollutants on surface ozone concentrations over Western China

Tropospheric ozone (O3) is a critical pollutant over the Mediterranean countries, including Portugal, due to systematic exceedances to the thresholds for the protection of human health. Due to the location of Portugal, on the Atlantic coast at the south-west point of Europe, the observed O3 concentrations are very much influenced not only by local and regional production but also by northern mid-latitudes background concentrations. Ozone trends in the Iberian Peninsula were previously analysed by Monteiro et al. (2012), based on 10-years of O3 observations. Nevertheless, only two of the eleven background monitoring stations analysed in that study are located in Portugal and these two stations are located in Porto and Lisbon urban areas. Although during pollution events O3 levels in urban areas may be high enough to affect human health, the highest concentrations are found in rural locations downwind from the urban and industrialized areas, rather than in cities. This happens because close to the sources (e.g., in urban areas) freshly emitted NO locally scavenges O3. A long-term study of the spatial and temporal variability and trends of the ozone concentrations over Portugal is missing, aiming to answer the following questions:-&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; What is the temporal variability of ozone concentrations?-&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Which trends can we find in observations?-&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; How were the ozone spring maxima concentrations affected by the COVID-19 lockdown during spring 2020?In this presentation, these questions will be answered based on the statistical analysis of O3 concentrations recorded within the national air quality monitoring network between 2005 and 2020 (16 years). The variability of the surface ozone concentrations over Portugal, on the timescales from diurnal to annual, will be presented and discussed, taking into account the physical and chemical processes that control that variability. Using the TheilSen function from the OpenAir package for R (Carslaw and Ropkins 2012), which quantifies monotonic trends and calculates the associated p-value through bootstrap simulations, O3 concentration long-term trends will be estimated for the different regions and environments (e.g., rural, urban).&#160; Moreover, taking advantage of the unique situation provided by the COVID-19 lockdown during spring 2020, when the government imposed mandatory confinement and citizens movement restriction, leading to a reduction in traffic-related atmospheric emissions, the role of these emissions on ozone levels during the spring period will be studied and presented.&#160;Carslaw and Ropkins, 2012. Openair&#8212;an R package for air quality data analysis. Environ. Model. Softw. 27-28,52-61. https://doi.org/10.1016/j.envsoft.2011.09.008Monteiro et al., 2012. Trends in ozone concentrations in the Iberian Peninsula by quantile regression and clustering. Atmos. Environ. 56, 184-193. https://doi.org/10.1016/j.atmosenv.2012.03.069

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Ozone Prediction Performance of HMM Based on the Data Compressed by Different Wavelet Basis Functions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.1586 ◽

2012 ◽

Vol 518-523 ◽

pp. 1586-1591

Author(s):

Hao Zhang ◽

Ze Meng Zhao ◽

Ahmet Palazoglu ◽

Wei Sun

Keyword(s):

Information Content ◽

Shannon Entropy ◽

Air Pollutants ◽

Surface Ozone ◽

Prediction Performance ◽

Basis Functions ◽

Wavelet Basis ◽

Human Beings ◽

Ozone Prediction ◽

Geometric Ratio

Surface ozone in the air boundary layer is one of the most harmful air pollutants produced by photochemical reaction between nitrogen oxides and volatile hydrocarbons, which causes great damage to human beings and environment. The prediction of surface ozone levels plays an important role in the control and the reduction of air pollutants. As model-driven statistical prediction models, hidden Markov Models (HMMs) are rich in mathematical structure and work well in many important applications. Due to the complex structure of HMM, long observation sequences would increase computational load by geometric ratio. In order to reduce training time, wavelet decomposition is used to compress the original observations into shorter ones. During compression step, observation sequences compressed by different wavelet basis functions keep different information content. This may have impact on prediction results. In this paper, ozone prediction performance of HMM based on different wavelet basis functions are discussed. Shannon entropy is employed to measure how much information content is kept in the new sequence compared to the original one. Data from Houston Metropolitan Area, TX are used in this paper. Results show that wavelet basis functions used in data compression step can affect the HMM model performance significantly. The new sequence with the maximum Shannon entropy generates the best prediction result.

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Observations of air composition in Brazil between the Equator and 20°s during the dry season.

Acta Amazonica ◽

10.1590/1809-43921985152119 ◽

1985 ◽

Vol 15 (1-2) ◽

pp. 77-120 ◽

Cited By ~ 1

Author(s):

P.J. Crutzen ◽

M.T. Coffey ◽

A.C. Delany ◽

J. Greenberg ◽

P. Haagenson ◽

...

Keyword(s):

Boundary Layer ◽

Carbon Monoxide ◽

Tropical Forests ◽

Air Pollutants ◽

Trace Gases ◽

Dry Season ◽

Photochemical Reactions ◽

Ozone Concentrations ◽

Air Chemistry ◽

High Concentrations

Field measurement programs in Brazil during the dry season months of August and September in 1979 and 1980 have demonstrated the great importance of the continental tropics in global air chemistry. Especially in the mixed layer, the air composition over land is much different from that over the ocean and the land areas are clearly longe scale sources of many inportant trace gases. During the dry season much biomass, burning takes place especially in the cerrado regions leading to substantial emission of air pollutants, such as CO, NOx, N2O, CH4 and other hydrocarbons. Ozone concentrations are alsoenhanced due to photochemical reactions. Biogenic organic emissions from tropical forests play likewise an important role in the photochemistry of the atmosphere. Carbon monoxide was found to be present in high concentrations in the boundary layer of the tropical forest, but ozone concentrations were much lower than in the cerrado.

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Characteristics of Surface Ozone Concentrations at Stations with Different Backgrounds in the Malaysian Peninsula

Aerosol and Air Quality Research ◽

10.4209/aaqr.2012.09.0259 ◽

2013 ◽

Vol 13 (3) ◽

pp. 1090-1106 ◽

Cited By ~ 27

Author(s):

Negar Banan ◽

Mohd Talib Latif ◽

Liew Juneng ◽

Fatimah Ahamad

Keyword(s):

Surface Ozone ◽

Ozone Concentrations

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Impacts of emission changes in China from 2010 to 2017 on domestic and intercontinental air quality and health effect

10.5194/acp-2021-385 ◽

2021 ◽

Author(s):

Yuqiang Zhang ◽

Drew Shindell ◽

Karl Seltzer ◽

Lu Shen ◽

Jean-Francois Lamarque ◽

...

Keyword(s):

Air Pollution ◽

Air Quality ◽

Air Pollutants ◽

Transport Model ◽

Surface Ozone ◽

Health Effect ◽

Premature Deaths ◽

Concentration Changes ◽

Emission Changes ◽

Related Mortality

Abstract. China has seen dramatic emission changes from 2010, especially after the implementation of Clean Air Action in 2013, with significant air quality and human health benefits observed. Air pollutants, such as PM2.5 and surface ozone, as well as their precursors, have long enough lifetime in the troposphere which can be easily transported downwind. So emission changes in China will not only change the regional air quality domestically, but also affect the air quality in downwind regions. In this study, we use a global chemistry transport model to simulate the influence on both domestic and foreign air quality from the emission change from 2010 to 2017 in China. By applying the health impact functions derived from epidemiology studies, we then quantify the changes in air pollution-related (including both PM2.5 and O3) mortality burdens at regional and global scales. The majority of air pollutants in China reach their peak values around 2012 and 2013. Compared with the year 2010, the population-weighted annual PM2.5 in China increases till 2011 (94.1 μg m−3), and then begins to decrease. In 2017, the population-weighted annual PM2.5 decreases by 17.6 %, compared with the values in 2010 (84.7 μg m−3). The estimated national PM2.5 concentration changes in China are comparable with previous studies using fine-resolution regional models, though our model tends to overestimate PM2.5 from 2013 to 2017 when evaluated with surface observation in China during the same periods. The emission changes in China increased the global PM2.5-related mortality burdens from 2010 to 2013, by 27,700 (95 %CI: 23,900–31, 400) deaths yr−1 in 2011, and 13, 300 (11,400–15,100) deaths yr−1 in 2013, among which at least 93 % occurred in China. The sharp emission decreases after 2013 bring significant benefits for reduced avoided premature mortality in 2017, reaching 108, 800 (92,800–124,800) deaths yr−1 globally, among which 92 % happening in China. Different trend as PM2.5, the annual maximum daily 8-hr ozone in China increased, and also the ozone-related premature deaths, ranging from 3,600 (2,700–4,300) deaths yr−1 in 2011 (75 % of global total increased premature deaths), and 8,500 (6,500–9,900) deaths yr−1 in 2017 (143 % of the global total). Downwind regions, such as South Korea, Japan, and U.S. generally see a decreased O3-related mortality burden after 2013 as a combination of increased export of ozone and decreased export of ozone precursors. In general, we conclude that the sharp emission reductions in China after 2013 bring benefits of improved air quality and reduced premature deaths associated with air pollution at global scale. The benefits are dominated by the PM2.5 decreases since the ozone is shown to actually increase with the emission decrease.

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Impacts of changes in land use and land cover on atmospheric chemistry and air quality over the 21st century

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-15469-2011 ◽

2011 ◽

Vol 11 (5) ◽

pp. 15469-15495 ◽

Cited By ~ 3

Author(s):

S. Wu ◽

L. J. Mickley ◽

J. O. Kaplan ◽

D. J. Jacob

Keyword(s):

Land Use ◽

Air Quality ◽

Land Use Change ◽

Land Cover ◽

21St Century ◽

Secondary Organic Aerosols ◽

Surface Ozone ◽

Organic Aerosols ◽

Ozone Concentrations ◽

Anthropogenic Land Use

Abstract. The effects of future land use and land cover change on the chemical composition of the atmosphere and air quality are largely unknown. To investigate the potential effects associated with future changes in vegetation driven by atmospheric CO2 concentrations, climate, and anthropogenic land use over the 21st century, we performed a series of model experiments combining a general circulation model with a dynamic global vegetation model and an atmospheric chemical-transport model. Our results indicate that climate- and CO2-induced changes in vegetation composition and density could lead to decreases in summer afternoon surface ozone of up to 10 ppb over large areas of the northern mid-latitudes. This is largely driven by the substantial increases in ozone dry deposition associated with changes in the composition of temperate and boreal forests where conifer forests are replaced by those dominated by broadleaf tree types, as well as a CO2-driven increase in vegetation density. Climate-driven vegetation changes over the period 2000–2100 lead to general increases in isoprene emissions, globally by 15 % in 2050 and 36 % in 2100. These increases in isoprene emissions result in decreases in surface ozone concentrations where the NOx levels are low, such as in remote tropical rainforests. However, over polluted regions, such as the northeastern United States, ozone concentrations are calculated to increase with higher isoprene emissions in the future. Increases in biogenic emissions also lead to higher concentrations of secondary organic aerosols, which increase globally by 10 % in 2050 and 20 % in 2100. Surface concentrations of secondary organic aerosols are calculated to increase by up to 1 μg m−3 for large areas in Eurasia. When we use a scenario of future anthropogenic land use change, we find less increase in global isoprene emissions due to replacement of higher-emitting forests by lower-emitting cropland. The global atmospheric burden of secondary organic aerosols changes little by 2100 when we account for future land use change, but both secondary organic aerosols and ozone show large regional changes at the surface.

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Contributions of pollutants from North China Plain to surface ozone at the Shangdianzi GAW Station

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-5889-2008 ◽

2008 ◽

Vol 8 (19) ◽

pp. 5889-5898 ◽

Cited By ~ 150

Author(s):

W. Lin ◽

X. Xu ◽

X. Zhang ◽

J. Tang

Keyword(s):

North China Plain ◽

North China ◽

Surface Ozone ◽

Surface Wind ◽

Ozone Pollution ◽

Ancillary Data ◽

Ozone Concentrations ◽

The North ◽

The North China Plain ◽

Autumn And Winter

Abstract. Regional ozone pollution has become one of the top environmental concerns in China, especially in those economically vibrant and densely populated regions, such as North China region including Beijing. To address this issue, surface ozone and ancillary data over the period 2004–2006 from the Shangdianzi Regional Background Station in north China were analyzed. Due to the suitable location and valley topography of the site, transport of pollutants from the North China Plain was easily observed and quantified according to surface wind directions. Regional (polluted) and background (clean) ozone concentrations were obtained by detailed statistic analysis. Contribution of pollutants from North China Plain to surface ozone at SDZ was estimated by comparing ozone concentrations observed under SW wind conditions and that under NE wind conditions. The average daily accumulated ozone contribution was estimated to be 240 ppb·hr. The average regional contributions to surface ozone at SDZ from the North China Plain were 21.8 ppb for the whole year, and 19.2, 28.9, 25.0, and 10.0 ppb for spring, summer, autumn, and winter, respectively. The strong ozone contribution in summer led to disappearance of the spring ozone maximum phenomenon at SDZ under winds other than from the NNW to E sectors. The emissions of nitrogen oxide in the North China plain cause a decrease in ozone concentrations in winter.

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The importance of stratospheric–tropospheric transport in affecting surface ozone concentrations in the western and northern tier of the United States

Atmospheric Environment ◽

10.1016/j.atmosenv.2011.06.014 ◽

2011 ◽

Vol 45 (28) ◽

pp. 4845-4857 ◽

Cited By ~ 63

Author(s):

Allen S. Lefohn ◽

Heini Wernli ◽

Douglas Shadwick ◽

Sebastian Limbach ◽

Samuel J. Oltmans ◽

...

Keyword(s):

United States ◽

Surface Ozone ◽

The United States ◽

Ozone Concentrations

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Seasonal prediction of US summertime ozone using statistical analysis of large scale climate patterns

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1610708114 ◽

2017 ◽

Vol 114 (10) ◽

pp. 2491-2496 ◽

Cited By ~ 16

Author(s):

Lu Shen ◽

Loretta J. Mickley

Keyword(s):

United States ◽

Large Scale ◽

Surface Ozone ◽

Tropical Atlantic ◽

Eastern United States ◽

Northeast Pacific ◽

Ozone Concentrations ◽

Climate Patterns ◽

Ocean Atmosphere ◽

Ozone Episodes

We develop a statistical model to predict June–July–August (JJA) daily maximum 8-h average (MDA8) ozone concentrations in the eastern United States based on large-scale climate patterns during the previous spring. We find that anomalously high JJA ozone in the East is correlated with these springtime patterns: warm tropical Atlantic and cold northeast Pacific sea surface temperatures (SSTs), as well as positive sea level pressure (SLP) anomalies over Hawaii and negative SLP anomalies over the Atlantic and North America. We then develop a linear regression model to predict JJA MDA8 ozone from 1980 to 2013, using the identified SST and SLP patterns from the previous spring. The model explains ∼45% of the variability in JJA MDA8 ozone concentrations and ∼30% variability in the number of JJA ozone episodes (>70 ppbv) when averaged over the eastern United States. This seasonal predictability results from large-scale ocean–atmosphere interactions. Warm tropical Atlantic SSTs can trigger diabatic heating in the atmosphere and influence the extratropical climate through stationary wave propagation, leading to greater subsidence, less precipitation, and higher temperatures in the East, which increases surface ozone concentrations there. Cooler SSTs in the northeast Pacific are also associated with more summertime heatwaves and high ozone in the East. On average, models participating in the Atmospheric Model Intercomparison Project fail to capture the influence of this ocean–atmosphere interaction on temperatures in the eastern United States, implying that such models would have difficulty simulating the interannual variability of surface ozone in this region.

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Vertical Distribution of Ozone and Nitrogenous Pollutants in an Air Quality Class I Area, the San Gorgonio Wilderness, Southern California

The Scientific World JOURNAL ◽

10.1100/tsw.2002.73 ◽

2002 ◽

Vol 2 ◽

pp. 10-26 ◽

Cited By ~ 8

Author(s):

Rocio Alonso ◽

Andrzej Bytnerowicz ◽

Michael Arbaugh

Keyword(s):

Nitric Acid ◽

Air Pollutants ◽

Elevation Gradient ◽

Temporal Distribution ◽

Air Pollutant ◽

Passive Samplers ◽

Class I ◽

San Bernardino Mountains ◽

Ozone Concentrations ◽

Wilderness Area

Information about spatial and temporal distribution of air pollutants is essential for better understanding of environmental stresses affecting forests and estimation of potential risks associated with air pollutants. Ozone and nitrogenous air pollutants were monitored along an elevation gradient in the Class I San Gorgonio Wilderness area (San Bernardino Mountains, California, U.S.) during the summer of 2000 (mid-June to mid-October). Passive samplers were exposed for 2-week periods at six sampling sites located at 300 m intervals ranging from 1200 to 2700 m elevation. Elevated concentrations of ozone were found in this area with summer 24-h hourly means ranging from 53 to 59 ppb. The highest ozone concentrations were detected in the period July 25 to August 8, reaching values of 64 to 72 ppb expressed as 2-week mean. Passive-sampler ozone data did not show a clear relationship with elevation, although during the periods with higher ozone levels, ozone concentrations were higher at those sites below 2000 m than at sites located above that elevation. All nitrogenous pollutants studied showed a consistent decrease of concentrations with elevation. Nitrogen dioxide (NO2) levels were low, decreasing with increasing elevation from 6.4 to 1.5 ppb summer means. Nitric oxide (NO) concentrations were around 1 to 2 ppb, which is within the range of the detection levels of the devices used. Nitric acid (HNO3) vapor concentrations were lower at higher elevations (summer means 1.9 to 2.5 μg m-3) than at lower elevations (summer means 4.3 to 5.1 μg m-3). Summer concentrations of ammonia (NH3) were slightly higher than nitric acid ranging from 6 μg m-3at the lowest site to 2.5 μg m-3registered at the highest elevation. Since complex interactions between ozone and nitrogenous air pollutants have already been described for forests, simultaneous information about the distribution of these pollutants is needed. This is particularly important in mountain terrain where no reliable models of air pollutant distribution exist.

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