scholarly journals Seasonal and spatial variability of surface ozone over China: contributions from background and domestic pollution

2011 ◽  
Vol 11 (7) ◽  
pp. 3511-3525 ◽  
Author(s):  
Y. Wang ◽  
Y. Zhang ◽  
J. Hao ◽  
M. Luo

Abstract. Both observations and a 3-D chemical transport model suggest that surface ozone over populated eastern China features a summertime trough and that the month when surface ozone peaks differs by latitude and region. Source-receptor analysis is used to quantify the contributions of background ozone and Chinese anthropogenic emissions on this variability. Annual mean background ozone over China shows a spatial gradient from 55 ppbv in the northwest to 20 ppbv in the southeast, corresponding with changes in topography and ozone lifetime. Pollution background ozone (annual mean of 12.6 ppbv) shows a minimum in the summer and maximum in the spring. On the monthly-mean basis, Chinese pollution ozone (CPO) has a peak of 20–25 ppbv in June north of the Yangtze River and in October south of it, which explains the peaks of surface ozone in these months. The summertime trough in surface ozone over eastern China can be explained by the decrease of background ozone from spring to summer (by −15 ppbv regionally averaged over eastern China). Tagged simulations suggest that long-range transport of ozone from northern mid-latitude continents (including Europe and North America) reaches a minimum in the summer, whereas ozone from Southeast Asia exhibits a maximum in the summer over eastern China. This contrast in seasonality provides clear evidence that the seasonal switch in monsoonal wind patterns plays a significant role in determining the seasonality of background ozone over China.

2010 ◽  
Vol 10 (11) ◽  
pp. 27853-27891 ◽  
Author(s):  
Y. Wang ◽  
Y. Zhang ◽  
J. Hao ◽  
M. Luo

Abstract. Both observations and a 3-D chemical transport model suggest that surface ozone over populated eastern China features a significant drop in mid-summer and that the peak month differs by latitude and region. Source-receptor analysis is used to quantify the contributions of background ozone and Chinese anthropogenic emissions on this variability. Annual mean background ozone over China shows a spatial gradient from 55 ppbv in the northwest to 20 ppbv in the southeast, corresponding with changes in topography and ozone lifetime. Anthropogenic background (annual mean of 12.6 ppbv) shows distinct troughs in the summer and peaks in the spring. On the monthly-mean basis, Chinese pollution ozone (CPO) has a peak of 20–25 ppbv in June north of the Yangtze River and in October south of it, which explains the peaks of surface ozone in these months. The mid-summer drop in ozone over eastern China is driven by the decrease of background ozone (−15 ppbv). Tagged simulations suggest that this decrease is driven by reduced transport from Europe and North America, whereas ozone from Southeast Asia and Pacific Ocean exhibits a maximum in the summer over eastern China. This contrast in seasonality provides clear evidence that the seasonal switch in monsoonal wind patterns plays a significant role in determining the seasonality of background ozone over China.


2010 ◽  
Vol 49 (2) ◽  
pp. 203-220 ◽  
Author(s):  
In-Bo Oh ◽  
Yoo-Keun Kim ◽  
Mi-Kyung Hwang ◽  
Cheol-Hee Kim ◽  
Soontae Kim ◽  
...  

Abstract Elevated layers of high ozone concentration were observed over the Seoul metropolitan region (SMR) in Korea by ozonesonde measurements during 6–9 June 2003. An analysis of the synoptic-scale meteorological features and backward trajectories revealed that the layers were associated with the long-range transport of ozone from eastern China. Further examination of the long-range transport process responsible for the development of these layers was performed using the Community Multiscale Air Quality (CMAQ) model. CMAQ demonstrated that the upward mixing of ozone by convective activity in eastern China and subsequent horizontal transport aloft in the periphery of a slow-moving high pressure system led to the development of thick ozone layers over the SMR. Through comparative simulation studies, it was found that the surface ozone levels in the SMR can be significantly enhanced by the vertical down-mixing of ozone from the layer aloft with the growing mixed layer. On average, about 25% of the surface peak concentration in a given area during a high-ozone episode was due to the influence of the ozone layer aloft developed by the long-range transport process.


2020 ◽  
Vol 13 (3) ◽  
pp. 1137-1153 ◽  
Author(s):  
Yadong Lei ◽  
Xu Yue ◽  
Hong Liao ◽  
Cheng Gong ◽  
Lin Zhang

Abstract. The terrestrial biosphere and atmospheric chemistry interact through multiple feedbacks, but the models of vegetation and chemistry are developed separately. In this study, the Yale Interactive terrestrial Biosphere (YIBs) model, a dynamic vegetation model with biogeochemical processes, is implemented into the Chemical Transport Model GEOS-Chem (GC) version 12.0.0. Within this GC-YIBs framework, leaf area index (LAI) and canopy stomatal conductance dynamically predicted by YIBs are used for dry deposition calculation in GEOS-Chem. In turn, the simulated surface ozone (O3) by GEOS-Chem affect plant photosynthesis and biophysics in YIBs. The updated stomatal conductance and LAI improve the simulated O3 dry deposition velocity and its temporal variability for major tree species. For daytime dry deposition velocities, the model-to-observation correlation increases from 0.69 to 0.76, while the normalized mean error (NME) decreases from 30.5 % to 26.9 % using the GC-YIBs model. For the diurnal cycle, the NMEs decrease by 9.1 % for Amazon forests, 6.8 % for coniferous forests, and 7.9 % for deciduous forests using the GC-YIBs model. Furthermore, we quantify the damaging effects of O3 on vegetation and find a global reduction of annual gross primary productivity by 1.5 %–3.6 %, with regional extremes of 10.9 %–14.1 % in the eastern USA and eastern China. The online GC-YIBs model provides a useful tool for discerning the complex feedbacks between atmospheric chemistry and the terrestrial biosphere under global change.


2020 ◽  
Author(s):  
Ning Yang ◽  
Yanru Bai ◽  
Yong Zhu ◽  
Nan Ma ◽  
Qiaoqiao Wang

<p>In the last six years, China has experienced significant improvement in air quality due to great emission reduction efforts. However, ozone concentrations are still slowly increasing in three major regions of eastern China, respectively Jing-Jin-Ji(JJJ), Yangtze River Delta region(YRD) and Pearl River Delta region(PRD). It is shown from the 2015-2018 national urban air quality real-time release platform that the surface ozone in JJJ, YRD and PRD has increased each year and reached the highest in 2018. The monthly ozone concentration peaked in June in almost all cities of JJJ, while it had multiple peaks in other two regions (summer and autumn in YRD - and February, May and September in PRD). Simulation with a chemical transport model(GEOS-Chem) indicates that the formation of ozone is affected by the optical properties of PM<sub>2.5</sub> and also the heterogeneous uptake of N<sub>2</sub>O<sub>5</sub> on sea salt aerosol.</p>


2018 ◽  
Vol 18 (1) ◽  
pp. 103-127 ◽  
Author(s):  
Matthieu Pommier ◽  
Hilde Fagerli ◽  
Michael Gauss ◽  
David Simpson ◽  
Sumit Sharma ◽  
...  

Abstract. Eleven of the world's 20 most polluted cities are located in India and poor air quality is already a major public health issue. However, anthropogenic emissions are predicted to increase substantially in the short-term (2030) and medium-term (2050) futures in India, especially if no further policy efforts are made. In this study, the EMEP/MSC-W chemical transport model has been used to predict changes in surface ozone (O3) and fine particulate matter (PM2.5) for India in a world of changing emissions and climate. The reference scenario (for present-day) is evaluated against surface-based measurements, mainly at urban stations. The evaluation has also been extended to other data sets which are publicly available on the web but without quality assurance. The evaluation shows high temporal correlation for O3 (r =  0.9) and high spatial correlation for PM2.5 (r =  0.5 and r =  0.8 depending on the data set) between the model results and observations. While the overall bias in PM2.5 is small (lower than 6 %), the model overestimates O3 by 35 %. The underestimation in NOx titration is probably the main reason for the O3 overestimation in the model. However, the level of agreement can be considered satisfactory in this case of a regional model being evaluated against mainly urban measurements, and given the inevitable uncertainties in much of the input data.For the 2050s, the model predicts that climate change will have distinct effects in India in terms of O3 pollution, with a region in the north characterized by a statistically significant increase by up to 4 % (2 ppb) and one in the south by a decrease up to −3 % (−1.4 ppb). This variation in O3 is assumed to be partly related to changes in O3 deposition velocity caused by changes in soil moisture and, over a few areas, partly also by changes in biogenic non-methane volatile organic compounds.Our calculations suggest that PM2.5 will increase by up to 6.5 % over the Indo-Gangetic Plain by the 2050s. The increase over India is driven by increases in dust, particulate organic matter (OM) and secondary inorganic aerosols (SIAs), which are mainly affected by the change in precipitation, biogenic emissions and wind speed.The large increase in anthropogenic emissions has a larger impact than climate change, causing O3 and PM2.5 levels to increase by 13 and 67 % on average in the 2050s over the main part of India, respectively. By the 2030s, secondary inorganic aerosol is predicted to become the second largest contributor to PM2.5 in India, and the largest in the 2050s, exceeding OM and dust.


2010 ◽  
Vol 10 (2) ◽  
pp. 4673-4717 ◽  
Author(s):  
D. Durnford ◽  
A. Dastoor ◽  
D. Figueras-Nieto ◽  
A. Ryjkov

Abstract. This study is the most extensive study to date on the transport of mercury to the Arctic. Moreover, it is the first such study to use a fully-coupled, online chemical transport model, Environment Canada's Global/Regional Atmospheric Heavy Metals model (GRAHM), where the meteorology and mercury processes are fully integrated. It is also the only study to date on the transport of mercury across Canada. We determined source attribution from Asia, North America, Russia and Europe at six arctic verification stations, as well as three subarctic and eight midlatitude Canadian stations. We have found that Asia, despite having transport efficiencies that were almost always lower than those of North America and often lower than those of Russia, was the dominant source of gaseous atmospheric mercury at all verification stations: it contributed the most mercury (29–37% at all stations, seasons and levels considered), its concentrations frequently explained nearly 100% of the variability in the concentrations produced by the simulation performed with full global emissions, particularly in the absence of local sources, and it generated the most long range transport (LRT) events, causing 43%, 67% and 75% of the events at the arctic, subarctic and midlatitude stations, respectively. For the Arctic, Russian transport efficiencies tended to be the strongest, as expected, while European and Asian efficiencies were lower and higher, respectively, than those found in the literature. This disagreement is likely produced by mercury's long lifetime relative to that of other pollutants. The accepted springtime preference for the trans-Pacific transport of Asian pollution was evident only in the midlatitude group of stations, being masked in the arctic and subarctic groups by the occurrence of atmospheric mercury depletion events. Some neighbouring arctic stations recorded dissimilar numbers of LRT events; despite their proximity, the behaviour of mercury at these stations was governed by different dynamics and transport pathways. The column burden of GEM in the lowest 5 km of the Northern Hemisphere was largest in summer from Asia, North America and Russia, but in winter from Europe. In the vertical, transport of mercury from all source regions occurred principally in the mid-troposphere.


2008 ◽  
Vol 8 (4) ◽  
pp. 16335-16379 ◽  
Author(s):  
D. R. Reidmiller ◽  
D. A. Jaffe ◽  
D. Chand ◽  
S. Strode ◽  
P. Swartzendruber ◽  
...  

Abstract. Interannual variations in background tropospheric trace gases (such as carbon monoxide, CO) are largely driven by variations in emissions (especially wildfires), transport pathways and tropospheric oxidizing capacity. Understanding this variability is essential to quantify the intercontinental contribution to US air quality. We investigate the interannual variability of long-range transport of Asian pollutants to the Northeast Pacific via measurements from the Mt. Bachelor Observatory (MBO: 43.98° N, 121.69° W; 2.7 km above sea level) and GEOS-Chem chemical transport model simulations in spring 2005 vs. the INTEX-B campaign during spring 2006. Measurements of CO at MBO were significantly enhanced during spring 2005 relative to the same time in 2006 (the INTEX-B study period); a monthly mean decline in CO of 41 ppbv was observed between April 2005 and April 2006. Meteorological indices show that long-range transport of CO from the heavily industrialized region of East Asia was significantly greater in 2005 than in 2006. In addition, spring 2005 was an anomalously strong biomass burning season in Southeast Asia. Data presented by Yurganov et al. (2008) using MOPITT satellite retrievals from this area reveal an average CO burden anomaly (referenced to March 2000–February 2002 mean values) between October 2004 through April 2005 of 2.6 Tg CO vs. 0.6 Tg CO for the same period a year later. The Naval Research Laboratory's global aerosol transport model shows that emissions from these fires were efficiently transported to MBO throughout April 2005. Asian dust transport, however, was substantially greater in 2006 than 2005, particularly in May. Monthly mean aerosol light scattering coefficient at 532 nm (σsp) at MBO more than doubled from 2.7 Mm−1 in May 2005 to 6.2 Mm−1 in May 2006. We also evaluate CO interannual variability throughout the western US via Earth System Research Laboratory ground site data and throughout the Northern Hemisphere via MOPITT and TES satellite observations. Both in the Northeast Pacific and on larger scales, we reveal a significant decrease (from 2–21%) in springtime maximum CO between 2005 and 2006, evident in all platforms and the GEOS-Chem model. We attribute this to (a) anomalously strong biomass burning in Southeast Asia during winter 2004 through spring 2005, and (b) the transport pattern in 2006 which limited the inflow of Asian pollution to the lower free troposphere over western North America.


2021 ◽  
Vol 21 (24) ◽  
pp. 18227-18245
Author(s):  
Amir H. Souri ◽  
Kelly Chance ◽  
Juseon Bak ◽  
Caroline R. Nowlan ◽  
Gonzalo González Abad ◽  
...  

Abstract. Questions about how emissions are changing during the COVID-19 lockdown periods cannot be answered by observations of atmospheric trace gas concentrations alone, in part due to simultaneous changes in atmospheric transport, emissions, dynamics, photochemistry, and chemical feedback. A chemical transport model simulation benefiting from a multi-species inversion framework using well-characterized observations should differentiate those influences enabling to closely examine changes in emissions. Accordingly, we jointly constrain NOx and VOC emissions using well-characterized TROPOspheric Monitoring Instrument (TROPOMI) HCHO and NO2 columns during the months of March, April, and May 2020 (lockdown) and 2019 (baseline). We observe a noticeable decline in the magnitude of NOx emissions in March 2020 (14 %–31 %) in several major cities including Paris, London, Madrid, and Milan, expanding further to Rome, Brussels, Frankfurt, Warsaw, Belgrade, Kyiv, and Moscow (34 %–51 %) in April. However, NOx emissions remain at somewhat similar values or even higher in some portions of the UK, Poland, and Moscow in March 2020 compared to the baseline, possibly due to the timeline of restrictions. Comparisons against surface monitoring stations indicate that the constrained model underrepresents the reduction in surface NO2. This underrepresentation correlates with the TROPOMI frequency impacted by cloudiness. During the month of April, when ample TROPOMI samples are present, the surface NO2 reductions occurring in polluted areas are described fairly well by the model (model: −21 ± 17 %, observation: −29 ± 21 %). The observational constraint on VOC emissions is found to be generally weak except for lower latitudes. Results support an increase in surface ozone during the lockdown. In April, the constrained model features a reasonable agreement with maximum daily 8 h average (MDA8) ozone changes observed at the surface (r=0.43), specifically over central Europe where ozone enhancements prevail (model: +3.73 ± 3.94 %, +1.79 ppbv, observation: +7.35 ± 11.27 %, +3.76 ppbv). The model suggests that physical processes (dry deposition, advection, and diffusion) decrease MDA8 surface ozone in the same month on average by −4.83 ppbv, while ozone production rates dampened by largely negative JNO2[NO2]-kNO+O3[NO][O3] become less negative, leading ozone to increase by +5.89 ppbv. Experiments involving fixed anthropogenic emissions suggest that meteorology contributes to 42 % enhancement in MDA8 surface ozone over the same region with the remaining part (58 %) coming from changes in anthropogenic emissions. Results illustrate the capability of satellite data of major ozone precursors to help atmospheric models capture ozone changes induced by abrupt emission anomalies.


2019 ◽  
Author(s):  
Viral Shah ◽  
Daniel J. Jacob ◽  
Ke Li ◽  
Rachel F. Silvern ◽  
Shixian Zhai ◽  
...  

Abstract. Satellite observations of tropospheric NO2 columns are extensively used to infer trends in anthropogenic emissions of nitrogen oxides (NOx ≡ NO + NO2), but this may be complicated by trends in NOx lifetime. Here we use 2004–2018 observations from the OMI satellite-based instrument (QA4ECV and POMINO v2 retrievals) to examine the seasonality and trends of tropospheric NO2 columns over central-eastern China, and we interpret the results with the GEOS-Chem chemical transport model. The observations show a factor of 3 increase in NO2 columns from summer to winter, which we explain in GEOS-Chem as reflecting a longer NOx lifetime in winter than in summer (21 h versus 5.9 h in 2017). The 2005–2018 summer trends of OMI NO2 closely follow the trends in the Multi-resolution Emission Inventory for China (MEIC), with a rise over the 2005–2011 period and a 25 % decrease since. We find in GEOS-Chem no significant trend of the NOx lifetime in summer, supporting the emission trend reported by MEIC. The winter trend of OMI NO2 is steeper than in summer over the entire period, which we attribute to a decrease in NOx lifetime at lower NOx emissions. Half of the NOx sink in winter is from N2O5 hydrolysis, which counterintuitively becomes more efficient as NOx emissions decrease due to less titration of ozone at night. Formation of organic nitrates also becomes an increasing sink of NOx as NOx emissions decrease but emissions of volatile organic compounds (VOCs) do not.


2019 ◽  
Vol 19 (7) ◽  
pp. 4459-4484 ◽  
Author(s):  
Arineh Cholakian ◽  
Augustin Colette ◽  
Isabelle Coll ◽  
Giancarlo Ciarelli ◽  
Matthias Beekmann

Abstract. Multiple CMIP5 (Coupled Model Intercomparison Project phase 5) future scenarios run with the CHIMERE chemistry transport model (CTM) are compared to historic simulations in order to study some of the drivers governing air pollution. Here, the focus is on regional climate, anthropogenic emissions and long-range transport. Two major subdomains are explored – the European region and the Mediterranean Basin – with both areas showing high sensitivity to climate change. The Mediterranean area is explored in the context of the ChArMEx (the Chemistry Aerosol Mediterranean Experiment) project, which examines the current and future meteorological and chemical conditions of the Mediterranean area. This climate impact study covers the period from 2031 to 2100 and considers possible future scenarios in comparison with 1976 to 2005 historic simulations using three Representative Concentration Pathways (RCPs; RCP2.6, RCP4.5 and RCP8.5). A detailed analysis of total PM10 (particulate matter with a diameter smaller that 10 µm) concentrations is carried out, including the evolution of PM10 and changes to its composition. The individual effects of meteorological conditions on PM10 components are explored in these scenarios in an effort to pinpoint the meteorological parameter(s) governing each component. The anthropogenic emission impact study covers the period from 2046 to 2055 using current legislation (CLE) and maximum feasible reduction (MFR) anthropogenic emissions for the year 2050 compared with historic simulations covering the period from 1996 to 2005 and utilizing CLE2010 emissions data. Long-range transport is explored by changing the boundary conditions in the chemistry transport model over the same period as the emission impact studies. Finally, a cumulative effect analysis of these drivers is performed, and the impact of each driver on PM10 and its components is estimated. The results show that regional climate change causes a decrease in the PM10 concentrations in our scenarios (in both the European and Mediterranean subdomains), as a result of a decrease in nitrate, sulfate, ammonium and dust atmospheric concentrations in most scenarios. On the contrary, BSOA (biogenic secondary organic aerosol) displays an important increase in all scenarios, showing more pronounced concentrations for the European subdomain compared with the Mediterranean region. Regarding the relationship of different meteorological parameters to concentrations of different species, nitrate and BSOA show a strong temperature dependence, whereas sulfate is most strongly correlated with relative humidity. The temperature-dependent behavior of BSOA changes when looking at the Mediterranean subdomain, where it displays more dependence on wind speed, due to the transported nature of BSOA existing in this subdomain. A cumulative look at all drivers shows that anthropogenic emission changes overshadow changes caused by climate and long-range transport for both of the subdomains explored, with the exception of dust particles for which long-range transport changes are more influential, especially in the Mediterranean Basin. For certain species (such as sulfates and BSOA), in most of the subdomains explored, the changes caused by anthropogenic emissions are (to a certain extent) reduced by the boundary conditions and regional climate changes.


Sign in / Sign up

Export Citation Format

Share Document