About
37
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Introduction
My research interests include air quality, climate change, and environmental solutions. Now I am working on surface ozone air quality in China. Contact me---> keli@nuist.edu.cn or
---> https://faculty.nuist.edu.cn/like/en/index.htm
Skills and Expertise
Publications
Publications (37)
Ozone (O3) is an important trace and greenhouse gas in the atmosphere, posing a threat to the ecological environment and human health at the ground level. Large-scale and long-term studies of O3 pollution in China are few due to highly limited direct ground and satellite measurements. This study offers a new perspective to estimate ground-level O3...
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...
Regional atmospheric circulation patterns affect haze pollution and they change in the warming climate. Here, the characteristics of atmospheric circulation anomalies conducive to extreme haze occurrence in China and their historical and future trends are examined based on surface observations, reanalysis data, aerosol source tagging technique, and...
Photochemical pollution over the North China Plain (NCP) is attracting much concern. We usually view peroxyacetyl nitrate (PAN) as the second most important photochemical pollutant featuring high mixing ratios during warm seasons. Our observations at a background site in the NCP identified high PAN concentrations, even during haze events in autumn....
China’s nationwide monitoring network initiated in 2013 has witnessed continuous increases of urban summertime surface ozone to 2019 by about 5% year ⁻¹ , among the fastest ozone trends in the recent decade reported in the Tropospheric Ozone Assessment Report. Here we report that surface ozone levels averaged over cities in eastern China cities dec...
Geostationary satellite measurements of aerosol optical depth (AOD) over East Asia from the Geostationary Ocean Color Imager (GOCI) and Advanced Himawari Imager (AHI) instruments can augment surface monitoring of fine particulate matter (PM2.5) air quality, but this requires better understanding of the AOD–PM2.5 relationship. Here we use the GEOS-C...
China is the world’s largest anthropogenic methane (CH4) emitter, with coal mine methane (CMM) as one of the main contributors. However, previous studies have not reach consensus on the magnitude and trend of China’s CMM emissions since 2010. Through distribution fitting and Monte Carlo methods, dynamic emission factors (EFs) of CMM at the province...
Ammonia (NH 3 ) emissions, mainly from agricultural sources, generate substantial health damage due to the adverse effects on air quality. NH 3 emission reduction strategies are still far from being effective. In particular, a growing trade network in this era of globalization offers untapped emission mitigation potential that has been overlooked....
Intensive agricultural activities in the North China Plain (NCP) lead to substantial emissions of nitrogen oxides (NO x ) from soil, while the role of this source on local severe ozone pollution is unknown. Here we use a mechanistic parameterization of soil NO x emissions combined with two atmospheric chemistry models to investigate the issue. We f...
The concentration of fine particulate matter (PM2.5) across China has decreased by 30–50% over the period 2013–2018 due to stringent emission controls. However, the nitrate component of PM2.5 has not responded effectively to decreasing emissions of nitrogen oxides and has actually increased during winter haze pollution events in the North China Pla...
Surface ozone is a severe air pollution problem in the North China Plain, which is home to 300 million people. Ozone concentrations are highest in summer, driven by fast photochemical production of hydrogen oxide radicals (HOx) that can overcome the radical titration caused by high emissions of nitrogen oxides (NOx) from fuel combustion. Ozone has...
Hydroxymethanesulfonate (HMS) has recently been identified as an abundant organosulfur compound in aerosols during winter haze episodes in northern China. It has also been detected in other regions although the concentrations are low. Because of the sparse field measurements, the global significance of HMS and its spatial and seasonal patterns rema...
High levels of secondary air pollutants during COVID-19 in China have aroused great concern. In Beijing, measured daily mean peroxyacetyl nitrate (PAN) concentrations reached 4 ppb over the lockdown period (01/24−02/15), whose averages were 2−3 times that before lockdown (01/01−01/23). The lockdown PAN levels also reached a high historical record b...
Surface ozone data from the Chinese Ministry of Ecology and Environment (MEE) network show sustained increases across the country over the 2013-2019 period. Despite Phase 2 of the Clean Air Action Plan targeting ozone pollution, ozone was higher in 2018-2019 than in previous years. The mean summer 2013-2019 trend in maximum 8 h average (MDA8) ozone...
Severe particulate pollution days (SPPDs, characterized by a daily mean PM2.5 concentration exceeding 150 μg m-3), which are extremely harmful to human health and the environment, occurred frequently in North China during the boreal winters of 2013–2019. SPPDs generally occur under conducive weather patterns (CWPs) characterized by a weakened East...
China’s nationwide ozone monitoring network initiated in 2013 has observed severe surface ozone pollution. This network, combined with the recent Tropospheric Ozone Assessment Report (TOAR) dataset, offers a more comprehensive view on global surface ozone distribution and trends. Here we report quantitative estimates of the warm-season (April-Septe...
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 Ozone Monitoring Instrument (OMI) satellite-based instrument (QA4ECV and POMINO v2 retrievals) to exami...
Fine particulate matter (PM2.5) decreased by 30–40% across China during 2013–2017 in response to the governmental Clean Air Action. However, surface ozone pollution worsened over the same period. Model simulations have suggested that the increase in ozone could be driven by the decrease in PM2.5, because PM2.5 scavenges hydroperoxy (HO2) and NOx ra...
Fine particulate matter (PM2.5) is a severe air pollution
problem in China. Observations of PM2.5 have been available since 2013
from a large network operated by the China National Environmental Monitoring
Center (CNEMC). The data show a general 30 %–50 % decrease in annual mean
PM2.5 across China over the 2013–2018 period, averaging at −5.2 µg m−3...
Severe surface ozone pollution over major Chinese cities has become an emerging air quality concern, raising a new challenge for emission control measures in China. In this study, we explore the source contributions to surface daily maximum 8 h average (MDA8) ozone over China in 2016 and 2017, the 2 years with the highest surface ozone averaged ove...
Nadir-viewing satellite observations of tropospheric ozone in the UV have been shown to have some sensitivity to boundary layer ozone pollution episodes, but so far they have not yet been compared to surface ozone observations collected by large-scale monitoring networks. Here we use 2013–2017 surface ozone data from China's new Ministry of Ecology...
We use 2005–2016 observations of formaldehyde (HCHO) columns over China from the OMI, GOME-2, and SCIAMACHY satellite instruments to evaluate long-term trends in emission inventories of volatile organic compounds (VOCs) that affect air quality. The observations show large increases over 2005–2016 in the North China Plain (+1.1 ± 0.5% a ⁻¹ relative...
Severe surface ozone pollution over major Chinese cities has become an emerging air quality concern, raising a new challenge for emission control measures in China. In this study, we explore the source contributions to surface daily maximum 8-h average (MDA8) ozone over China in 2016 and 2017, the two years with the highest surface ozone averaged o...
Observations of surface ozone available from ∼1,000 sites across China for the past 5 years (2013–2017) show severe summertime pollution and regionally variable trends. We resolve the effect of meteorological variability on the ozone trends by using a multiple linear regression model. The residual of this regression shows increasing ozone trends of...
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This study applies the nested-grid version of Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem) to examine future changes (2000–2050) in SOA concentration and associated direct radiative forcing (DRF) over China under the Representative Concentration Pathways (RCPs). The projected changes in SOA concentrations over 2010–205...
Severe haze pollution in eastern China has caused substantial health impacts and economic loss. Conducive atmospheric conditions are important to affect occurrence of severe haze events, and circulation changes induced by future global climate warming are projected to increase the frequency of such events. However, a potential contribution of an an...
The frequency of Beijing winter severe haze episodes has increased substantially over the past decades1, 2, 3, 4, and is commonly attributed to increased pollutant emissions from China’s rapid economic development5, 6. During such episodes, levels of fine particulate matter are harmful to human health and the environment, and cause massive disrupti...
Severe PM2.5 air pollution in China and the First Grand National Standard (FGNS), implemented in 2016 (annual PM2.5 concentration target of less than 35 µg m−3), necessitate urgent reduction strategies. This study applied the nested-grid version of the GEOS-Chem model to quantify 2000–2050 changes in PM2.5 air quality and related direct radiative f...
We quantify the contributions from five domestic emission sectors (residential, industry, transportation, energy, and biomass burning) and emissions outside of China (non-China) to concentration and direct radiative forcing (DRF) of black carbon (BC) in China for year 2010 using a nested-grid version of the global chemical transport model (GEOS-Che...
Projects
Projects (2)
Ozone pollution is an emerging environmental issue in China, and episodes exceeding 120 ppbv occur frequently under stagnant weather in warm seasons in megacities such as Beijing and Shanghai. Aerosol could affect ozone through changes in photolysis rates and aerosol chemistry by uptaking gases. This project aims to obtain a better understanding of how emission precursors, aerosols, and meteorology drive current ozone pollution in China.
Understand historical and future trends of haze pollution and their driving factors in eastern China, using integrated global chemical transport model, climate models, and statistical methods.
