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Introduction
Tropospheric ozone, Atmospheric oxidants, Tropospheric chemistry
Publications
Publications (79)
Global chemical transport models (CTMs) are used extensively to study air pollution and transport at a global scale. These models are limited by coarse horizontal resolutions that do not allow for a detailed representation of small-scale nonlinear processes over the pollutant source regions. Here we couple the global GEOS-Chem CTM and its three hig...
Small-scale nonlinear chemical and physical processes over pollution source
regions affect the tropospheric ozone (O3), but these processes are not captured by current global chemical transport models (CTMs) and
chemistry–climate models that are limited by coarse horizontal resolutions
(100–500 km, typically 200 km). These models tend to contain la...
The Goddard Earth Observing System with chemistry (GEOS-Chem) model has been updated with the State-wide Air Pollution Research Center version 11 (SAPRC-11) aromatics chemical mechanism, with the purpose of evaluating global and regional effects of the most abundant aromatics (benzene, toluene, xylenes) on the chemical species important for troposp...
In the United States, the decline of summertime daytime peak ozone in the last 20 years has been clearly connected to reductions in anthropogenic emissions. However, questions remain about how and through what mechanisms ozone at other times of day have changed over recent decades. Here we analyze the interannual variability and trends of ozone at...
Surface-based measurements from the EMEP and Airbase networks are used to estimate the changes in surface ozone levels during the 1995–2014 period over Europe. We find significant ozone enhancements (0.20–0.59 µg m-3 yr-1 for the annual means; P-value < 0.01 according to an F-test) over the European suburban and urban stations during 1995–2012 base...
In recent years, the concentrations of ozone and the pollution days with ozone as the primary pollutant have been increasing year by year. The sources of regional ozone mainly depend on local photochemical formation and transboundary transport. The latter is influenced by different weather circulations. How to effectively reduce the inter-regional...
Fine particulate matter (PM2.5) and ozone (O3) double high pollution (DHP) events have occurred frequently over China in recent years, but their causes are not completely clear. In this study, the spatiotemporal distribution of DHP events in China during 2013–20 is analyzed. The synoptic types affecting DHP events are identified with the Lamb–Jenki...
Surface ozone, which is a major air pollutant, has gained widespread public attention due to its significant harm to human health and ecosystems. Here we find that long-term trends of surface ozone are largely influenced by stratosphere-troposphere exchange (STE) using the historical simulations in the CMIP6 multi-model ensemble. It is found that S...
Extratropical cyclones (ETCs) are one of the primary weather systems affecting China. However, atmospheric environmental effects generated under the control of ETCs are rarely reported. In this study, we investigate air quality in Beijing from the perspective of ETCs. The ETCs affecting Beijing from 2014 to 2021 are tracked using the 850 hPa relati...
There has been controversy regarding the air pollutants emitted from sources closely related to the activities of daily life in China, such as cooking, setting off fireworks, sacrificial incense and joss paper burning, and barbecue (which have been named the five missing sources – FMSs), and the extent to which they impact the outdoor air quality....
Ozone pollution is a major transboundary threat to global health. Systematic improvement of mitigation strategy for transboundary ozone requires a socioeconomic understanding of historical lessons in countries at different affluence levels. Here, we explore the changes in transboundary ozone related premature deaths over 1951–2019 driven by anthrop...
Summertime ozone pollution has become increasingly severe over many parts of China in recent years. Due to lack of historical ozone observations, few studies have analyzed the linkage between natural climate variability and ozone levels for a long time series. This study uses the simulation datasets from CMIP6 to explore the effects of El Niño–Sout...
There has been controversy about the air pollutants emitted from sources closely related to people's daily life (such as cooking, fireworks burning, sacrificial incenses and joss paper burning, and barbecue, named as five missing sources, FMS) impacting the outdoor air quality to what extent. Till now, there is no emission estimation of air polluta...
Hot extremes, ultraviolet (UV) radiation, and surface ozone all have prominent effects on human health and ecosystems. Here we show evidence that both hot extremes and high surface UV radiation at noon time occur concurrently in summer over the Yangtze Plain. Composite analysis suggests that hot extremes in summer are primarily caused by the westwa...
The widespread and high use of biomass fuels (BF) by farmers contribute to air pollution-associated health impacts. However, the toxicity and spatial health risks of heavy metals in PM2.5 from BF burning, especially for elements (Cr, As, Cd, Hg, and Pb) listed as hazardous air pollutants (HAPs) in China, remain unknown on the national scale. This s...
The effects of meteorological conditions controlled by specific synoptic patterns on regional surface ozone episodes have been widely discussed. However, the impacts of synoptic climate systems and their interaction on long-term variation of ozone are less known. In this study, we use the daily meteorological data and hourly surface ozone concentra...
Global tropospheric nitrogen dioxide (NO2) changes have different or even opposite impacts on the photochemical formation of ozone in different regions under different weather and emission condition. However, the changes over regions affected by different levels of human activities are not well known. By using the Ozone Monitoring Instrument (OMI)...
Corncob is one of the major biomass sources and widely adopted as fuel in rural China. However, only few studies have discussed the emissions from corncob burning. The negligence of corncob burning emissions has resulted in biased or even unreasonable biomass burning emission results. In this study, the emission factors (EFs) of corncob burning wer...
Residential coal combustion (RCC) emission exhibited obvious daily variation, while no real-time estimation of air pollutants from RCC has been reported, as the shortages of corresponding activity dataset and emission factors with high time resolution. A real-time monitoring platform for RCC emission was established. Hourly emission factors of 18 t...
Aromatic hydrocarbons, including benzene, toluene, and xylenes, play an important role in atmospheric chemistry, but the associated chemical mechanisms are complex and uncertain. Sparing representation of this chemistry in models is needed for computational tractability. Here, we develop a new compact mechanism for aromatic chemistry (GC13) that ca...
The result of Aethalometer model to black carbon (BC) source apportionment is highly determined by the absorption Ångström exponent ( α ) of aerosols from fossil fuel combustion ( α ff ) and wood burning ( α wb ). A method using hourly measured potassium to calculate the α ff and α wb values was developed in this study. Results showed that the opti...
Residential coal combustion (RCC) emission demonstrates obvious daily variation, while no real-time estimation of air pollutants from RCC has been reported, as the limitation of hourly activity data and emission factors. With a dilution sampling system, a high-precision electronic balance, and an Aethalometer Model AE33, a real-time monitoring plat...
Atmospheric ammonia (NH3) is one of the most crucial precursors of secondary inorganic aerosols. However, its emission control is still weakness over China. NH3 emission inventories of 2015 with and without considering a set of refined emission reduction strategies covering seven major NH3 emission sources were constructed in Central China. GEOS-Ch...
In recent years, severe air pollution has had a serious impact on the health and economy of residents and has attracted great attention. Due to the spatial separation between consumption and production, the transfer of PM2.5 pollution and its health and economic effects caused by interprovincial trade have not been taken seriously. In this study, e...
Aromatic hydrocarbons (mainly benzene, toluene, and xylenes) play an important role in atmospheric chemistry but the associated chemical mechanisms are complex and uncertain. Spare representation of this chemistry in models is needed for computational tractability. Here we develop a new compact mechanism for aromatic chemistry (GC13) that captures...
The less improvement of ambient visibility suspects the government's efforts on alleviating PM 2.5 pollution. The COVID-19 lockdown reduced PM 2.5 and increased visibility in Wuhan. Compared to pre-lockdown period, the PM 2.5 concentration decreased by 39.0 μg m −3 , dominated by NH 4 NO 3 mass reduction (24.8 μg m −3) during lockdown period. The P...
In recent years, ozone pollution has attracted wide attention from the scientific community, policymakers and the public. Previous studies have already confirmed the effects of meteorological conditions on regional ozone pollution events in the last two decades. However, due to the lack of historical ozone observations, the relationship of climate...
Accurate source markers, source profiles and species-based emission factors (EFs) are currently the key limitations for source apportionment and emission inventory researches. Fine particles (PM2.5) were collected from stack gases of eight types of stationary sources with a dilution sampling system. The mass percentages and EFs of 89 kinds of chemi...
Currently, mitigating severe particle pollution in autumn and winter is the key to further improving the air quality of China. The source contributions and transboundary transport of fine particles (PM2.5) in pollution episodes are closely related to large-scale or synoptic-scale atmospheric circulation. How to effectively reduce emissions to contr...
Volatile organic compounds (VOCs) are important contributors to atmospheric chemical reactivity rate (L OH), ozone formation potential (OFP), and secondary organic aerosol formation potential (SOAP). The purpose of this study was to determine the contributions of different VOC sources to L OH , OFP, and SOAP using positive matrix factorization (PMF...
Distinct city-level characteristics in ozone and precursors are found. • Substantial variabilities are found in photochemical formation of ozone across the cities and days. • Removing a city's local anthropogenic emissions alone can effectively mitigate ozone pollution. A B S T R A C T Mitigation of ozone in urban agglomerations of developing count...
Levoglucosan (LG) emitted from non-biomass burning (non-BB) sources has given rise to biased or even unreasonable source identification results when adopting LG as a distinct marker of biomass burning (BB). The estimation of LG emission and its spatiotemporal variation for various sources are the keys to reducing uncertainty. This study first devel...
Research Highlight: • Mass and optical properties closures for size-resolved aerosols were investigated. • Sources of optical properties for size-resolved aerosols were apportioned. • Impacts of BB on optical properties for size-resolved aerosols were quantified. Aerosol size distribution, chemical components and their mixing state are key factors...
Currently solving the severe particle pollution in autumn and winter is the key to 23 further improve the air quality of China. The source contributions and transboundary 24 transport of fine particles (PM 2.5) in pollution episodes are closely related to large-scale 25 or synoptic-scale atmospheric circulation. Under different synoptic conditions,...
Biomass burning (BB) has significant impacts on air quality, climate and human health. In China, the BB emission has changed substantially over the past decades while the multi-year variation held high uncertainty and the driving forces have addressed little attention. Here, this research aimed to conduct a comprehensive and systematic analysis of...
We present a new product with explicit aerosol corrections, POMINO-TROPOMI, for tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) over East Asia, based on the newly launched TROPOspheric Monitoring Instrument with an unprecedented high horizontal resolution. Compared to the official TM5-MP-DOMINO (OFFLINE) product, POMINO-TROPOMI...
The absence of emission factors (EFs) with high-time resolution primarily hinders developing high time-resolution emission inventory for air pollutants, which further restricted the accuracy of air quality modeling, especially for a pollution process. The real-time emission concentration of volatile organic compounds (VOCs) in the combustion proces...
Source profiles of volatile organic compounds (VOCs) emitted from the evaporation of various fuels, industrial raw materials, processes and products are still limited in China. The impact of ambient temperature on the VOC released from these fugitive emission sources has also been rarely reported. In order to establish VOC source profiles for thirt...
Wuhan was the first city to adopt the lockdown measures to prevent COVID-19 spreading, which improved the air quality accordingly. This study investigated the variations in chemical compositions, source contributions, and regional transport of fine particles (PM2.5) during January 23–February 22 of 2020, compared with the same period in 2019. The a...
Particles emitted from five typical types of vehicles (including light-duty gasoline vehicles, LDG; heavy-duty gasoline vehicles, HDG; diesel buses, BUS; light-duty diesel vehicles, LDD and heavy-duty diesel vehicles, HDD) were collected with a dilution sampling system and an electrical low-pressure impactor (ELPI+, with particle sizes covering fou...
The contributions to aerosols and major chemical compositions (e.g. water-soluble ions-WSIs) from residential coal combustion (RCC) are still now existing large uncertainty in air quality modeling. The lake of reliable emission inventories for primary WSIs from RCC in China with measured emission factors (EFs) adopted is a major obstacle. With simu...
Abstract. We present a new product with explicit aerosol corrections, POMINO-TROPOMI, for tropospheric nitrogen dioxide (NO<sub>2</sub>) vertical column densities (VCDs) over East Asia, based on the newly launched TROPOspheric Monitoring Instrument with an unprecedented high horizontal resolution. Compared to the official TM5-MP-DOMINO (OFFLINE) pr...
Ammonia control has received increasing attention as a measure to decrease particulate concentrations. Modeling analysis of observation data from central China over the period of September 2015 to August 2016 shows clear asymmetric responses of particulate pH and mass to ammonia emissions. With a change of ±80% of NHx (NH3 + NH4⁺), the correspondin...
Residential coal combustion is one of the main sources of ambient polycyclic aromatic hydrocarbons (PAHs). Updating its emission estimation is limited by the shortages of emission factors, especially for them in different particle sizes and from different combustion conditions. PAH emission factors (EFs) for nine size-segregated particle segments e...
Despite much effort made in studying human health associated with fine particulate matter (PM2.5), our knowledge about PM2.5 and human health from a long-term perspective is still limited by inadequately long data. Here, we presented a novel method to retrieve surface PM2.5 mass concentrations using surface visibility measurements and GEOS-Chem mod...
Petrochemical industry (PI) is an important emission sector of anthropogenic volatile organic compounds (VOCs). The health impacts of VOCs from PI have caused a wide attention by both scientists and publics. In this study, compositions, sources and health risks of VOCs at a typical petrochemical industrial park along the middle reach of Yangtze Riv...
Emission datasets of nitrogen oxides (NOx) at high horizontal resolutions (e.g., 0.05∘×0.05∘) are crucial for understanding human influences at fine scales, air quality studies, and pollution control. Yet high-resolution emission data are often missing or contain large uncertainties especially for the developing regions. Taking advantage of long-te...
Airborne fungi are a primary component of bioaerosols and proved to impact human health and climatic change. Deoxyribonucleic acid (DNA) is the essential component of most living organisms with relatively stable physicochemical properties. Little is known about day-night and pollution-episode differences of DNA mass ratio and fungal community in fi...
The trends per 5th percentile interval of European surface ozone concentrations over urban, suburban and rural sites in the period 1995–2012 have been estimated based on observational data from the European Environment Agency air quality database. Consistent with previous study results, we find a rapid decline of relatively high ozone concentration...
Black carbon (BC), which is formed from the incomplete combustion of fuel sources (mainly fossil fuel, biofuel and open biomass burning), is a chemically inert optical absorber in the atmosphere. It has significant impacts on global climate, regional air quality and human health. During transportation, its physical and chemical characteristics as w...
Recent studies have shown that surface ozone (O3) concentrations over central eastern China (CEC) have increased significantly during the past decade. We quantified the effects of changes in meteorological conditions and O3 precursor emissions on surface O3 levels over CEC between July 2003 and July 2015 using the GEOS-Chem model. The simulated mon...
Satellite retrieval of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) is critical for NOx pollution and impact evaluation. For regions with high aerosol loadings, the retrieval accuracy is greatly affected by whether aerosol optical effects are treated implicitly (as additional “effective” clouds) or explicitly, among other...
Black carbon (BC), from the incomplete combustion sources (mainly fossil fuel, biofuel and open biomass burning), 17 is chemically inertness and optical absorbance in the atmosphere. It has significant impacts on global climate, regional air 18 quality, and human health. During the transportation, its physical-chemical characteristics, optical prop...
supplementary for Intra-regional transport of black carbon between North China Plain and Central China during winter haze episodes
Eastern China (27–41∘ N, 110–123∘ E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 µm (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characte...
The GEOS-Chem model has been updated with the SAPRC-11 aromatics chemical mechanism, with the purpose of evaluating global and regional effects of the most abundant aromatics (benzene, toluene, xylenes) on the chemical species important for tropospheric oxidation capacity. The model evaluation based on surface and aircraft observations indicates go...
China is facing a severe ozone problem, but the origin of its ozone remains unclear. Here we use a GEOS-Chem based global–regional two-way coupled model system to quantify the individual contributions of eight emission source regions worldwide to springtime ozone in 2008 over China. The model reproduces the observed ozone from 31 ground sites and v...
Recent studies have shown that surface ozone (O3) concentrations over Central Eastern China (CEC) have increased significantly during the past decade. We quantified the effects of changes in meteorological conditions and O3 precursor emissions on surface O3 levels over CEC between July 2003 and July 2015 using the GEOS-Chem model. The simulated mon...
Satellite retrieval of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) is critical for NOx pollution and impact evaluation. For regions with high aerosol loadings, the retrieval accuracy is greatly affected by whether aerosol optical effects are treated implicitly (as additional effective clouds) or explicitly, among other f...
Eastern China (27° N–41° N, 110° E–123° E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 μm (PM2.5) and other air pollutants. These pollutants vary in a variety of temporal and spatial scales, with many temporal scales non-periodic and non-stationary, challenging proper quantitative characteri...
China is facing a severe ozone problem, but the origin of its ozone remains unclear. Here we use a GEOS-Chem based global-regional two-way coupled model system to quantify the individual contributions of eight emission source regions worldwide to springtime ozone in 2008 over China. The model reproduces the observed ozone from 31 ground sites and v...