Yuan Wang is an assistant professor in the Department of Earth System Science at the Stanford Doerr School of Sustainability. He is also an affiliated faculty in the Woods Institute for the Environment. Prior to joining Stanford, he was an associate professor at Purdue University and a research scientist at California Institute of Technology. His research group aims to advance the understanding of the physical and chemical interactions between atmospheric constituents and climate change. Specifically, his group conducts research related to aerosol-cloud-precipitation interactions and their climatic implications, aerosol properties and haze formation, cloud microphysics and dynamics, and the assessment of the greenhouse gas and aerosol forcings on the atmosphere, ocean, and cryosphere. They develop and use hierarchical and multiscale weather and climate models in combination with space-borne and in situ measurements to address those scientific questions. Dr. Wang is a recipient of the James B. Macelwane Medal and James R. Holton Award from the American Geophysical Union, and Henry G. Houghton Award from the American Meteorological Society.

Academic Appointments

Honors & Awards

  • Henry G. Houghton Award, American Meteorological Society (2024)
  • Fellow, American Geophysical Union (2023)
  • James B. Macelwane Medal, American Geophysical Union (2023)
  • Turco Lectureship: Future Horizons in Climate Science, American Geophysical Union (2021)
  • Journal of the Atmospheric Sciences Editor’s Award, American Meteorological Society (2017)
  • James R. Holton Award, American Geophysical Union (2016)
  • Early Career Scientist Medal, International Association of Meteorology and Atmospheric Sciences (2015)
  • Best Thesis Award, Springer (2014)
  • Distinguished Graduate Student Award, Texas A&M University (2014)
  • Earth and Space Science Fellowship, NASA (2009-2012)
  • The Regents’ Scholarship, Texas A&M University (2008)

Boards, Advisory Committees, Professional Organizations

  • Chair, AMS Committee on Atmospheric Chemistry (2024 - Present)
  • Editor-in-Chief, npj Clean Air (2024 - Present)
  • Committee Member, AGU Union Medal Selection Committee (2024 - Present)
  • Committee Member, AMS Atmospheric Research Award Committee (2024 - Present)
  • Editor, Atmospheric Chemistry and Physics (2022 - Present)
  • Associate Editor, Journal of Advances in Modeling the Earth System (2022 - 2024)
  • Associate Editor, Journal of the Atmospheric Sciences (2017 - 2021)
  • Committee Member, AGU Atmospheric Sciences Early Career Committee (2019 - 2021)

Professional Education

  • B.S., Fudan University, Computer Science (2007)
  • Ph.D, Texas A&M University, Atmospheric Sciences (2013)

2023-24 Courses

Stanford Advisees

All Publications

  • Effects of smoke on marine low clouds and radiation during 2020 western United States wildfires ATMOSPHERIC RESEARCH Dong, L., Wang, M., Rosenfeld, D., Zhu, Y., Wang, Y., Dong, X., Liu, Z., Wang, H., Zeng, Y., Cao, Y., Lu, X., Liu, J., Shen, W. 2024; 302
  • Distinct PM<sub>2.5</sub>-Related Near-Term Climate Penalties Induced by Different Clean Air Measures in China GEOPHYSICAL RESEARCH LETTERS Gao, D., Zhao, B., Wang, S., Shen, J., Wang, Y., Zhou, C., Jiang, J., Wu, Q., Li, S., Sun, Y., He, Y., Zhu, Y., Jiang, Z. 2024; 51 (8)
  • An updated modeling framework to simulate Los Angeles air quality - Part 1: Model development, evaluation, and source apportionment ATMOSPHERIC CHEMISTRY AND PHYSICS Pennington, E. A., Wang, Y., Schulze, B. C., Seltzer, K. M., Yang, J., Zhao, B., Jiang, Z., Shi, H., Venecek, M., Chau, D., Murphy, B. N., Kenseth, C. M., Ward, R. X., Pye, H. T., Seinfeld, J. H. 2024; 24 (4): 2345-2363
  • Radiative and Microphysical Impacts of the Saharan Dust on Two Concurrent Tropical Cyclones: Danielle and Earl (2010) JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Pan, B., Wang, Y., Lin, Y., Hsieh, J., Lavallee, M., Zhao, L., Zhang, R. 2024; 129 (2)
  • Dynamic Traffic Data in Machine-Learning Air Quality Mapping Improves Environmental Justice Assessment. Environmental science & technology Wen, Y., Zhang, S., Wang, Y., Yang, J., He, L., Wu, Y., Hao, J. 2024


    Air pollution poses a critical public health threat around many megacities but in an uneven manner. Conventional models are limited to depict the highly spatial- and time-varying patterns of ambient pollutant exposures at the community scale for megacities. Here, we developed a machine-learning approach that leverages the dynamic traffic profiles to continuously estimate community-level year-long air pollutant concentrations in Los Angeles, U.S. We found the introduction of real-world dynamic traffic data significantly improved the spatial fidelity of nitrogen dioxide (NO2), maximum daily 8-h average ozone (MDA8 O3), and fine particulate matter (PM2.5) simulations by 47%, 4%, and 15%, respectively. We successfully captured PM2.5 levels exceeding limits due to heavy traffic activities and providing an "out-of-limit map" tool to identify exposure disparities within highly polluted communities. In contrast, the model without real-world dynamic traffic data lacks the ability to capture the traffic-induced exposure disparities and significantly underestimate residents' exposure to PM2.5. The underestimations are more severe for disadvantaged communities such as black and low-income groups, showing the significance of incorporating real-time traffic data in exposure disparity assessment.

    View details for DOI 10.1021/acs.est.3c07545

    View details for PubMedID 38261755

  • Microphysical complexity of black carbon particles restricts their warming potential ONE EARTH Huang, X., Peng, Y., Wei, J., Peng, J., Lin, X., Tang, M., Cheng, Y., Men, Z., Fang, T., Zhang, J., He, L., Cao, L., Liu, C., Zhang, C., Mao, H., Seinfeld, J. H., Wang, Y. 2024; 7 (1)
  • Consumption Based Source Apportionment Indicates Different Regional Contributions to O<sub>3</sub> Concentrations and Health Effects ENGINEERING Zhu, S., Wang, P., Wang, S., Geng, G., Zhao, H., Wang, Y., Zhang, H. 2023; 28: 130-138
  • The weekly cycle of photosynthesis in Europe reveals the negative impact of particulate pollution on ecosystem productivity. Proceedings of the National Academy of Sciences of the United States of America He, L., Rosa, L., Lobell, D. B., Wang, Y., Yin, Y., Doughty, R., Yao, Y., Berry, J. A., Frankenberg, C. 2023; 120 (49): e2306507120


    Aerosols can affect photosynthesis through radiative perturbations such as scattering and absorbing solar radiation. This biophysical impact has been widely studied using field measurements, but the sign and magnitude at continental scales remain uncertain. Solar-induced fluorescence (SIF), emitted by chlorophyll, strongly correlates with photosynthesis. With recent advancements in Earth observation satellites, we leverage SIF observations from the Tropospheric Monitoring Instrument (TROPOMI) with unprecedented spatial resolution and near-daily global coverage, to investigate the impact of aerosols on photosynthesis. Our analysis reveals that on weekends when there is more plant-available sunlight due to less particulate pollution, 64% of regions across Europe show increased SIF, indicating more photosynthesis. Moreover, we find a widespread negative relationship between SIF and aerosol loading across Europe. This suggests the possible reduction in photosynthesis as aerosol levels increase, particularly in ecosystems limited by light availability. By considering two plausible scenarios of improved air quality-reducing aerosol levels to the weekly minimum 3-d values and levels observed during the COVID-19 period-we estimate a potential of 41 to 50 Mt net additional annual CO2 uptake by terrestrial ecosystems in Europe. This work assesses human impacts on photosynthesis via aerosol pollution at continental scales using satellite observations. Our results highlight i) the use of spatiotemporal variations in satellite SIF to estimate the human impacts on photosynthesis and ii) the potential of reducing particulate pollution to enhance ecosystem productivity.

    View details for DOI 10.1073/pnas.2306507120

    View details for PubMedID 37983483

  • Increased importance of aerosol-cloud interactions for surface PM<sub>2.5</sub> pollution relative to aerosol-radiation interactions in China with the anthropogenic emission reductions ATMOSPHERIC CHEMISTRY AND PHYSICS Gao, D., Zhao, B., Wang, S., Wang, Y., Gaudet, B., Zhu, Y., Wang, X., Shen, J., Li, S., He, Y., Yin, D., Dong, Z. 2023; 23 (22): 14359-14373
  • Assessing the destructiveness of tropical cyclones induced by anthropogenic aerosols in an atmosphere-ocean coupled framework ATMOSPHERIC CHEMISTRY AND PHYSICS Lin, Y., Wang, Y., Hsieh, J., Jiang, J. H., Su, Q., Zhao, L., Lavallee, M., Zhang, R. 2023; 23 (21): 13835-13852
  • An Aerosol Optical Module With Observation-Constrained Black Carbon Properties for Global Climate Models JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS Chen, G., Wang, J., Wang, Y., Wang, J., Jin, Y., Cheng, Y., Yin, Y., Liao, H., Ding, A., Wang, S., Hao, J., Liu, C. 2023; 15 (10)
  • Characterization of the aerosol vertical distributions and their impacts on warm clouds based on multi-year ARM observations. The Science of the total environment Lin, Y., Takano, Y., Gu, Y., Wang, Y., Zhou, S., Zhang, T., Zhu, K., Wang, J., Zhao, B., Chen, G., Zhang, D., Fu, R., Seinfeld, J. 2023; 904: 166582


    Aerosol vertical distribution plays a crucial role in cloud development and thus precipitation since both aerosol indirect and semi-direct effects significantly depend on the relative position of aerosol layer in reference to cloud, but its precise influence on cloud remains unclear. In this study, we integrated multi-year Raman Lidar measurements of aerosol vertical profiles from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) facility with available Value-Added Products of cloud features to characterize aerosol vertical distributions and their impacts on warm clouds over the continental and marine ARM atmospheric observatories, i.e., Southern Great Plains (SGP) and Eastern North Atlantic (ENA). A unimodal seasonal distribution of aerosol optical depths (AODs) with a peak in summer is found at upper boundary layer over SGP, while a bimodal distribution is observed at ENA for the AODs at lower levels with a major winter-spring maximum. The diurnal mean of upper-level AOD at SGP shows a maximum in the early evening. According to the relative positions of aerosol layers to clouds we further identify three primary types of aerosol vertical distribution, including Random, Decreasing, and Bottom. It is found that the impacts of aerosols on cloud may or may not vary with aerosol vertical distribution depending on environmental conditions, as reflected by the wide variations of the relations between AOD and cloud properties. For example, as AOD increases, the liquid water paths (LWPs) tend to be reduced at SGP but enhanced at ENA. The relations of cloud droplet effective radius with AOD largely depend on aerosol vertical distributions, particularly showing positive values in the Random type under low-LWP condition (<50 g m-2). The distinct features of aerosol-cloud interactions in relation to aerosol vertical distribution are likely attributed to the continental-marine contrast in thermodynamic environments and aerosol conditions between SGP and ENA.

    View details for DOI 10.1016/j.scitotenv.2023.166582

    View details for PubMedID 37634734

  • Insights of warm-cloud biases in Community Atmospheric Model 5 and 6 from the single-columnmodeling framework and Aerosol and Cloud Experiments in the EasternNorth Atlantic (ACE-ENA) observations ATMOSPHERIC CHEMISTRY AND PHYSICS Wang, Y., Zheng, X., Dong, X., Xi, B., Yung, Y. L. 2023; 23 (15): 8591-8605
  • Elucidating climatic drivers of photosynthesis by tropical forests GLOBAL CHANGE BIOLOGY Wang, Y., Liu, J., Wennberg, P. O., He, L., Bonal, D., Kohler, P., Frankenberg, C., Sitch, S., Friedlingstein, P. 2023


    Tropical forests play a pivotal role in regulating the global carbon cycle. However, the response of these forests to changes in absorbed solar energy and water supply under the changing climate is highly uncertain. Three-year (2018-2021) spaceborne high-resolution measurements of solar-induced chlorophyll fluorescence (SIF) from the TROPOspheric Monitoring Instrument (TROPOMI) provide a new opportunity to study the response of gross primary production (GPP) and more broadly tropical forest carbon dynamics to differences in climate. SIF has been shown to be a good proxy for GPP on monthly and regional scales. Combining tropical climate reanalysis records and other contemporary satellite products, we find that on the seasonal timescale, the dependence of GPP on climate variables is highly heterogeneous. Following the principal component analyses and correlation comparisons, two regimes are identified: water limited and energy limited. GPP variations over tropical Africa are more correlated with water-related factors such as vapor pressure deficit (VPD) and soil moisture, while in tropical Southeast Asia, GPP is more correlated with energy-related factors such as photosynthetically active radiation (PAR) and surface temperature. Amazonia is itself heterogeneous: with an energy-limited regime in the north and water-limited regime in the south. The correlations of GPP with climate variables are supported by other observation-based products, such as Orbiting Carbon Observatory-2 (OCO2) SIF and FluxSat GPP. In each tropical continent, the coupling between SIF and VPD increases with the mean VPD. Even on the interannual timescale, the correlation of GPP with VPD is still discernable, but the sensitivity is smaller than the intra-annual correlation. By and large, the dynamic global vegetation models in the TRENDY v8 project do not capture the high GPP seasonal sensitivity to VPD in dry tropics. The complex interactions between carbon and water cycles in the tropics illustrated in this study and the poor representation of this coupling in the current suite of vegetation models suggest that projections of future changes in carbon dynamics based on these models may not be robust.

    View details for DOI 10.1111/gcb.16837

    View details for Web of Science ID 001022772500001

    View details for PubMedID 37401204

  • Vertical Dependency of Aerosol Impacts on Local Scale Convective Precipitation GEOPHYSICAL RESEARCH LETTERS Sun, Y., Wang, Y., Zhao, C., Zhou, Y., Yang, Y., Yang, X., Fan, H., Zhao, X., Yang, J. 2023; 50 (2)
  • New Progress and Challenges in Cloud-Aerosol-Radiation-Precipitation Interactions: Preface for a Special Issue ADVANCES IN ATMOSPHERIC SCIENCES Zhao, C., Wang, Y., Letu, H. 2022; 39 (12): 1983-1985
  • Marked Impacts of Pollution Mitigation on Crop Yields in China EARTHS FUTURE He, L., Wei, J., Wang, Y., Shang, Q., Liu, J., Yin, Y., Frankenberg, C., Jiang, J. H., Li, Z., Yung, Y. L. 2022; 10 (11)
  • Notable impact of wildfires in the western United States on weather hazards in the central United States PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhang, Y., Fan, J., Shrivastava, M., Homeyer, C. R., Wang, Y., Seinfeld, J. H. 2022; 119 (44): e2207329119


    Increased wildfire events constitute a significant threat to life and property in the United States. Wildfire impact on severe storms and weather hazards is another pathway that threatens society, and our understanding of which is very limited. Here, we use unique modeling developments to explore the effects of wildfires in the western US (mainly California and Oregon) on precipitation and hail in the central US. We find that the western US wildfires notably increase the occurrences of heavy precipitation rates by 38% and significant severe hail (≥2 in.) by 34% in the central United States. Both heat and aerosols from wildfires play an important role. By enhancing surface high pressure and increasing westerly and southwesterly winds, wildfires in the western United States produce (1) stronger moisture and aerosol transport to the central United States and (2) larger wind shear and storm-relative helicity in the central United States. Both the meteorological environment more conducive to severe convective storms and increased aerosols contribute to the enhancements of heavy precipitation rates and large hail. Moreover, the local wildfires in the central US also enhance the severity of storms, but their impact is notably smaller than the impact of remote wildfires in California and Oregon because of the lessened severity of the local wildfires. As wildfires are projected to be more frequent and severe in a warmer climate, the influence of wildfires on severe weather in downwind regions may become increasingly important.

    View details for DOI 10.1073/pnas.2207329119

    View details for Web of Science ID 000896737400012

    View details for PubMedID 36252100

    View details for PubMedCentralID PMC9636965

  • Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud ADVANCES IN ATMOSPHERIC SCIENCES Zheng, X., Dong, X., Ward, D. M., Xi, B., Wu, P., Wang, Y. 2022; 39 (12): 2107-2123
  • Compensating Errors in Cloud Radiative and Physical Properties over the Southern Ocean in the CMIP6 Climate Models ADVANCES IN ATMOSPHERIC SCIENCES Zhao, L., Wang, Y., Zhao, C., Dong, X., Yung, Y. L. 2022; 39 (12): 2156-2171
  • This is FAST: multivariate Full-permutAtion based Stochastic foresT method-improving the retrieval of fine-mode aerosol microphysical properties with multi-wavelength lidar REMOTE SENSING OF ENVIRONMENT Wang, N., Xiao, D., Veselovskii, I., Wang, Y., Russell, L. M., Zhao, C., Guo, J., Li, C., Gross, S., Liu, X., Ni, X., Tan, L., Liu, Y., Zhang, K., Tong, Y., Wu, L., Chen, F., Wang, B., Liu, C., Chen, W., Liu, D. 2022; 280
  • The Hunga Tonga-Hunga Ha'apai Hydration of the Stratosphere GEOPHYSICAL RESEARCH LETTERS Millan, L., Santee, M. L., Lambert, A., Livesey, N. J., Werner, F., Schwartz, M. J., Pumphrey, H. C., Manney, G. L., Wang, Y., Su, H., Wu, L., Read, W. G., Froidevaux, L. 2022; 49 (13): e2022GL099381


    Following the 15 January 2022 Hunga Tonga-Hunga Ha'apai eruption, several trace gases measured by the Aura Microwave Limb Sounder (MLS) displayed anomalous stratospheric values. Trajectories and radiance simulations confirm that the H2O, SO2, and HCl enhancements were injected by the eruption. In comparison with those from previous eruptions, the SO2 and HCl mass injections were unexceptional, although they reached higher altitudes. In contrast, the H2O injection was unprecedented in both magnitude (far exceeding any previous values in the 17-year MLS record) and altitude (penetrating into the mesosphere). We estimate the mass of H2O injected into the stratosphere to be 146 ± 5 Tg, or ∼10% of the stratospheric burden. It may take several years for the H2O plume to dissipate. This eruption could impact climate not through surface cooling due to sulfate aerosols, but rather through surface warming due to the radiative forcing from the excess stratospheric H2O.

    View details for DOI 10.1029/2022GL099381

    View details for Web of Science ID 000822766100001

    View details for PubMedID 35865735

    View details for PubMedCentralID PMC9285945

  • Formation, radiative forcing, and climatic effects of severe regional haze ATMOSPHERIC CHEMISTRY AND PHYSICS Lin, Y., Wang, Y., Pan, B., Hu, J., Guo, S., Zamora, M., Tian, P., Su, Q., Ji, Y., Zhao, J., Gomez-Hernandez, M., Hu, M., Zhang, R. 2022; 22 (7): 4951-4967
  • Dual-field-of-view high-spectral-resolution lidar: Simultaneous profiling of aerosol and water cloud to study aerosol-cloud interaction PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wang, N., Zhang, K., Shen, X., Wang, Y., Li, J., Li, C., Mao, J., Malinka, A., Zhao, C., Russell, L. M., Guo, J., Gross, S., Liu, C., Yang, J., Chen, F., Wu, L., Chen, S., Ke, J., Xiao, D., Zhou, Y., Fang, J., Liu, D. 2022; 119 (10): e2110756119


    SignificanceAerosol-cloud interaction affects the cooling of Earth's climate, mostly by activation of aerosols as cloud condensation nuclei that can increase the amount of sunlight reflected back to space. But the controlling physical processes remain uncertain in current climate models. We present a lidar-based technique as a unique remote-sensing tool without thermodynamic assumptions for simultaneously profiling diurnal aerosol and water cloud properties with high resolution. Direct lateral observations of cloud properties show that the vertical structure of low-level water clouds can be far from being perfectly adiabatic. Furthermore, our analysis reveals that, instead of an increase of liquid water path (LWP) as proposed by most general circulation models, elevated aerosol loading can cause a net decrease in LWP.

    View details for DOI 10.1073/pnas.2110756119

    View details for Web of Science ID 000772220900017

    View details for PubMedID 35235447

    View details for PubMedCentralID PMC8915832

  • Environmental effects on aerosol-cloud interaction in non-precipitating marine boundary layer (MBL) clouds over the eastern North Atlantic ATMOSPHERIC CHEMISTRY AND PHYSICS Zheng, X., Xi, B., Dong, X., Wu, P., Logan, T., Wang, Y. 2022; 22 (1): 335-354
  • Health risk and disease burden attributable to long-term global fine-mode particles CHEMOSPHERE Yang, X., Wang, Y., Zhao, C., Fan, H., Yang, Y., Chi, Y., Shen, L., Yan, X. 2022; 287: 132435


    Particulate matter 2.5 (PM2.5) pollution has long been a global environmental problem and still poses a great threat to public health. This study investigates global spatiotemporal variations in PM2.5 using the newly developed satellite-derived PM2.5 dataset from 1998 to 2018. An integrated exposure-response (IER) model was employed to examine the characteristics of PM2.5-related deaths caused by chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD), lung cancer (LC), and stroke in adults (age≥25), as well as lower respiratory infection (LRI) in children (age≤5). The results showed that high annual PM2.5 concentrations were observed mainly in East Asia and South Asia. Over the 19-year period, PM2.5 concentrations constantly decreased in developed regions, but increased in most developing regions. Approximately 84% of the population lived in regions where PM2.5 concentrations exceeded 10 μg/m3. Meanwhile, the vast majority of the population (>60%) in East and South Asia was consistently exposed to PM2.5 levels above 35 μg/m3. PM2.5 exposure was linked to 3.38 (95% UI: 3.05-3.70) million premature deaths globally in 2000, a number that increased to 4.11 (95% UI: 3.55-4.69) million in 2018. Premature deaths related to PM2.5 accounted for 6.54%-7.79% of the total cause of deaths worldwide, with a peak in 2011. Furthermore, developing regions contributed to the majority (85.95%-95.06%) of PM2.5-related deaths worldwide, and the three highest-ranking regions were East Asia, South Asia, and Southeast Asia. Globally, IHD and stroke were the two main contributors to total PM2.5-related deaths, followed by COPD, LC, and LRI.

    View details for DOI 10.1016/j.chemosphere.2021.132435

    View details for Web of Science ID 000704945100005

    View details for PubMedID 34606897

  • From COVID-19 to future electrification: Assessing traffic impacts on air quality by a machine-learning model PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Yang, J., Wen, Y., Wang, Y., Zhang, S., Pinto, J. P., Pennington, E. A., Wang, Z., Wu, Y., Sander, S. P., Jiang, J. H., Hao, J., Yung, Y. L., Seinfeld, J. H. 2021; 118 (26)


    The large fluctuations in traffic during the COVID-19 pandemic provide an unparalleled opportunity to assess vehicle emission control efficacy. Here we develop a random-forest regression model, based on the large volume of real-time observational data during COVID-19, to predict surface-level NO2, O3, and fine particle concentration in the Los Angeles megacity. Our model exhibits high fidelity in reproducing pollutant concentrations in the Los Angeles Basin and identifies major factors controlling each species. During the strictest lockdown period, traffic reduction led to decreases in NO2 and particulate matter with aerodynamic diameters <2.5 μm by -30.1% and -17.5%, respectively, but a 5.7% increase in O3 Heavy-duty truck emissions contribute primarily to these variations. Future traffic-emission controls are estimated to impose similar effects as observed during the COVID-19 lockdown, but with smaller magnitude. Vehicular electrification will achieve further alleviation of NO2 levels.

    View details for DOI 10.1073/pnas.2102705118

    View details for Web of Science ID 000671767800005

    View details for PubMedID 34155113

    View details for PubMedCentralID PMC8256029

  • Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation ENVIRONMENTAL SCIENCE & TECHNOLOGY Li, Y., Zhao, J., Wang, Y., Seinfeld, J. H., Zhang, R. 2021; 55 (13): 8592-8603


    Photooxidation of volatile organic compounds (VOCs) produces secondary organic aerosol (SOA) and light-absorbing brown carbon (BrC) via multiple reaction steps/pathways, reflecting significant chemical complexity relevant to gaseous oxidation and subsequent gas-to-particle conversion. Toluene is an important VOC under urban conditions, but the fundamental chemical mechanism leading to SOA formation remains uncertain. Here, we elucidate multigeneration SOA production from toluene by simultaneously tracking the evolutions of gas-phase oxidation and aerosol formation in a reaction chamber. Large size increase and browning of monodisperse sub-micrometer seed particles occur shortly after initiating oxidation by hydroxyl radical (OH) at 10-90% relative humidity (RH). The evolution in gaseous products and aerosol properties (size/density/optical properties) and chemical speciation of aerosol-phase products indicate that the aerosol growth and browning result from earlier generation products consisting dominantly of dicarbonyl and carboxylic functional groups. While volatile dicarbonyls engage in aqueous reactions to yield nonvolatile oligomers and light-absorbing nitrogen heterocycles/heterochains (in the presence of NH3) at high RH, organic acids contribute to aerosol carboxylates via ionic dissociation or acid-base reaction in a wide RH range. We conclude that toluene contributes importantly to SOA/BrC formation from dicarbonyls and organic acids because of their prompt and high yields from photooxidation and unique functionalities for participation in aerosol-phase reactions.

    View details for DOI 10.1021/acs.est.1c02026

    View details for Web of Science ID 000671872100014

    View details for PubMedID 34137267

  • The Role of Primary Emission and Transboundary Transport in the Air Quality Changes During and After the COVID-19 Lockdown in China GEOPHYSICAL RESEARCH LETTERS Fan, H., Wang, Y., Zhao, C., Yang, Y., Yang, X., Sun, Y., Jiang, S. 2021; 48 (7): e2020GL091065


    In late January 2020, China's rapid and strict control measures to curb the COVID-19 spread led to a sharp halt in socio-economic activity and a significant reduction in emissions. Using the ground-based observational data, the authors synergistically quantify the nation-wide variations of major air pollutant as well as meteorology during and after the lockdown. Their concentrations (except O3) exhibited significant reduction during February and March 2020, by more than 24% during the lockdown compared with the earlier time period and by more than 17% compared with that in the same period in 2019. In contrast, ozone increased rapidly by about 60% across the country during the lockdown. Abnormal increases in carbon monoxide and particulate matter concentrations in southwest China are attributed to the severe wildfires in Southeast Asia. The concentration of air pollutants bounced back rapidly after the full-scale reopen in March 2020, indicating the decisive role of emissions in the pollution formation.

    View details for DOI 10.1029/2020GL091065

    View details for Web of Science ID 000641974600017

    View details for PubMedID 34230714

    View details for PubMedCentralID PMC8249991

  • New Observational Constraints on Warm Rain Processes and Their Climate Implications GEOPHYSICAL RESEARCH LETTERS Dong, X., Wu, P., Wang, Y., Xi, B., Huang, Y. 2021; 48 (6)
  • Unexpected Oligomerization of Small α-Dicarbonyls for Secondary Organic Aerosol and Brown Carbon Formation ENVIRONMENTAL SCIENCE & TECHNOLOGY Li, Y., Ji, Y., Zhao, J., Wang, Y., Shi, Q., Peng, J., Wang, Y., Wang, C., Zhang, F., Wang, Y., Seinfeld, J. H., Zhang, R. 2021; 55 (8): 4430-4439


    Large amounts of small α-dicarbonyls (glyoxal and methylglyoxal) are produced in the atmosphere from photochemical oxidation of biogenic isoprene and anthropogenic aromatics, but the fundamental mechanisms leading to secondary organic aerosol (SOA) and brown carbon (BrC) formation remain elusive. Methylglyoxal is commonly believed to be less reactive than glyoxal because of unreactive methyl substitution, and available laboratory measurements showed negligible aerosol growth from methylglyoxal. Herein, we present experimental results to demonstrate striking oligomerization of small α-dicarbonyls leading to SOA and BrC formation on sub-micrometer aerosols. Significantly more efficient growth and browning of aerosols occur upon exposure to methylglyoxal than glyoxal under atmospherically relevant concentrations and in the absence/presence of gas-phase ammonia and formaldehyde, and nonvolatile oligomers and light-absorbing nitrogen-heterocycles are identified as the dominant particle-phase products. The distinct aerosol growth and light absorption are attributed to carbenium ion-mediated nucleophilic addition, interfacial electric field-induced attraction, and synergetic oligomerization involving organic/inorganic species, leading to surface- or volume-limited reactions that are dependent on the reactivity and gaseous concentrations. Our findings resolve an outstanding discrepancy concerning the multiphase chemistry of small α-dicarbonyls and unravel a new avenue for SOA and BrC formation from atmospherically abundant, ubiquitous carbonyls and ammonia/ammonium sulfate.

    View details for DOI 10.1021/acs.est.0c08066

    View details for Web of Science ID 000643546400024

    View details for PubMedID 33721996

  • Insights into particulate matter pollution in the North China Plain during wintertime: local contribution or regional transport? ATMOSPHERIC CHEMISTRY AND PHYSICS Wu, J., Bei, N., Wang, Y., Li, X., Liu, S., Liu, L., Wang, R., Yu, J., Le, T., Zuo, M., Shen, Z., Cao, J., Tie, X., Li, G. 2021; 21 (3): 2229-2249
  • Author Correction: Near-real-time monitoring of global CO2 emissions reveals the effects of the COVID-19 pandemic. Nature communications Liu, Z., Ciais, P., Deng, Z., Lei, R., Davis, S. J., Feng, S., Zheng, B., Cui, D., Dou, X., Zhu, B., Guo, R., Ke, P., Sun, T., Lu, C., He, P., Wang, Y., Yue, X., Wang, Y., Lei, Y., Zhou, H., Cai, Z., Wu, Y., Guo, R., Han, T., Xue, J., Boucher, O., Boucher, E., Chevallier, F., Tanaka, K., Wei, Y., Zhong, H., Kang, C., Zhang, N., Chen, B., Xi, F., Liu, M., Bréon, F. M., Lu, Y., Zhang, Q., Guan, D., Gong, P., Kammen, D. M., He, K., Schellnhuber, H. J. 2020; 11 (1): 6292


    A Correction to this paper has been published:

    View details for DOI 10.1038/s41467-020-20254-5

    View details for PubMedID 33268773

    View details for PubMedCentralID PMC7709803

  • Impacts of long-range transport of aerosols on marine-boundary-layer clouds in the eastern North Atlantic ATMOSPHERIC CHEMISTRY AND PHYSICS Wang, Y., Zheng, X., Dong, X., Xi, B., Wu, P., Logan, T., Yung, Y. L. 2020; 20 (23): 14741-14755
  • Quantifying Long-Term Seasonal and Regional Impacts of North American Fire Activity on Continental Boundary Layer Aerosols and Cloud Condensation Nuclei EARTH AND SPACE SCIENCE Logan, T., Dong, X., Xi, B., Zheng, X., Wang, Y., Wu, P., Marlow, E., Maddux, J. 2020; 7 (12)
  • Air quality impact of the Northern California Camp Fire of November 2018 ATMOSPHERIC CHEMISTRY AND PHYSICS Rooney, B., Wang, Y., Jiang, J. H., Zhao, B., Zeng, Z., Seinfeld, J. H. 2020; 20 (23): 14597-14616
  • Determinant Role of Aerosols From Industrial Sources in Hurricane Harvey's Catastrophe GEOPHYSICAL RESEARCH LETTERS Pan, B., Wang, Y., Logan, T., Hsieh, J., Jiang, J. H., Li, Y., Zhang, R. 2020; 47 (23)
  • Near-real-time monitoring of global CO2 emissions reveals the effects of the COVID-19 pandemic NATURE COMMUNICATIONS Liu, Z., Ciais, P., Deng, Z., Lei, R., Davis, S. J., Feng, S., Zheng, B., Cui, D., Dou, X., Zhu, B., Guo, R., Ke, P., Sun, T., Lu, C., He, P., Wang, Y., Yue, X., Wang, Y., Lei, Y., Zhou, H., Cai, Z., Wu, Y., Guo, R., Han, T., Xue, J., Boucher, O., Boucher, E., Chevallier, F., Tanaka, K., Wei, Y., Zhong, H., Kang, C., Zhang, N., Chen, B., Xi, F., Liu, M., Breon, F., Lu, Y., Zhang, Q., Guan, D., Gong, P., Kammen, D. M., He, K., Schellnhuber, H. 2020; 11 (1): 5172


    The COVID-19 pandemic is impacting human activities, and in turn energy use and carbon dioxide (CO2) emissions. Here we present daily estimates of country-level CO2 emissions for different sectors based on near-real-time activity data. The key result is an abrupt 8.8% decrease in global CO2 emissions (-1551 Mt CO2) in the first half of 2020 compared to the same period in 2019. The magnitude of this decrease is larger than during previous economic downturns or World War II. The timing of emissions decreases corresponds to lockdown measures in each country. By July 1st, the pandemic's effects on global emissions diminished as lockdown restrictions relaxed and some economic activities restarted, especially in China and several European countries, but substantial differences persist between countries, with continuing emission declines in the U.S. where coronavirus cases are still increasing substantially.

    View details for DOI 10.1038/s41467-020-18922-7

    View details for Web of Science ID 000582680400008

    View details for PubMedID 33057164

    View details for PubMedCentralID PMC7560733

  • Tracking the atmospheric pulse of a North American megacity from a mountaintop remote sensing observatory REMOTE SENSING OF ENVIRONMENT Zeng, Z., Wang, Y., Pongetti, T. J., Gong, F., Newman, S., Li, Y., Natraj, V., Shia, R., Yung, Y. L., Sander, S. P. 2020; 248
  • Retrieval of Ice-Over-Water Cloud Microphysical and Optical Properties Using Passive Radiometers GEOPHYSICAL RESEARCH LETTERS Teng, S., Liu, C., Zhang, Z., Wang, Y., Sohn, B., Yung, Y. L. 2020; 47 (16)
  • Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China SCIENCE Le, T., Wang, Y., Liu, L., Yang, J., Yung, Y. L., Li, G., Seinfeld, J. H. 2020; 369 (6504): 702-+


    The absence of motor vehicle traffic and suspended manufacturing during the coronavirus disease 2019 (COVID-19) pandemic in China enabled assessment of the efficiency of air pollution mitigation. Up to 90% reduction of certain emissions during the city-lockdown period can be identified from satellite and ground-based observations. Unexpectedly, extreme particulate matter levels simultaneously occurred in northern China. Our synergistic observation analyses and model simulations show that anomalously high humidity promoted aerosol heterogeneous chemistry, along with stagnant airflow and uninterrupted emissions from power plants and petrochemical facilities, contributing to severe haze formation. Also, because of nonlinear production chemistry and titration of ozone in winter, reduced nitrogen oxides resulted in ozone enhancement in urban areas, further increasing the atmospheric oxidizing capacity and facilitating secondary aerosol formation.

    View details for DOI 10.1126/science.abb7431

    View details for Web of Science ID 000559184400048

    View details for PubMedID 32554754

    View details for PubMedCentralID PMC7402623

  • Identifying airborne transmission as the dominant route for the spread of COVID-19 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhang, R., Li, Y., Zhang, A. L., Wang, Y., Molina, M. J. 2020; 117 (26): 14857-14863


    Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing the effectiveness of those intervention practices hinges on the understanding of virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent and represents the dominant route to spread the disease. By analyzing the trend and mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020, we illustrate that the impacts of mitigation measures are discernable from the trends of the pandemic. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the pandemic trends in the three epicenters. This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9. Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public. We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic. Our work also highlights the fact that sound science is essential in decision-making for the current and future public health pandemics.

    View details for DOI 10.1073/pnas.2009637117

    View details for Web of Science ID 000548160900013

    View details for PubMedID 32527856

    View details for PubMedCentralID PMC7334447

  • Carbenium ion-mediated oligomerization of methylglyoxal for secondary organic aerosol formation PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ji, Y., Shi, Q., Li, Y., An, T., Zheng, J., Peng, J., Gao, Y., Chen, J., Li, G., Wang, Y., Zhang, F., Zhang, A. L., Zhao, J., Molina, M. J., Zhang, R. 2020; 117 (24): 13294-13299


    Secondary organic aerosol (SOA) represents a major constituent of tropospheric fine particulate matter, with profound implications for human health and climate. However, the chemical mechanisms leading to SOA formation remain uncertain, and atmospheric models consistently underpredict the global SOA budget. Small α-dicarbonyls, such as methylglyoxal, are ubiquitous in the atmosphere because of their significant production from photooxidation of aromatic hydrocarbons from traffic and industrial sources as well as from biogenic isoprene. Current experimental and theoretical results on the roles of methylglyoxal in SOA formation are conflicting. Using quantum chemical calculations, we show cationic oligomerization of methylglyoxal in aqueous media. Initial protonation and hydration of methylglyoxal lead to formation of diols/tetrol, and subsequent protonation and dehydration of diols/tetrol yield carbenium ions, which represent the key intermediates for formation and propagation of oligomerization. On the other hand, our results reveal that the previously proposed oligomerization via hydration for methylglyoxal is kinetically and thermodynamically implausible. The carbenium ion-mediated mechanism occurs barrierlessly on weakly acidic aerosols and cloud/fog droplets and likely provides a key pathway for SOA formation from biogenic and anthropogenic emissions.

    View details for DOI 10.1073/pnas.1912235117

    View details for Web of Science ID 000546040300025

    View details for PubMedID 32493751

    View details for PubMedCentralID PMC7306812

  • Reduced European aerosol emissions suppress winter extremes over northern Eurasia (vol 10, pg 225, 2020) NATURE CLIMATE CHANGE Wang Yuan, Le Tianhao, Chen Gang, Yung, Y. L., Su Hui, Seinfeld, J. H., Jiang, J. H. 2020; 10 (6): 582
  • Aerosol-photolysis interaction reduces particulate matter during wintertime haze events. Proceedings of the National Academy of Sciences of the United States of America Wu, J., Bei, N., Hu, B., Liu, S., Wang, Y., Shen, Z., Li, X., Liu, L., Wang, R., Liu, Z., Cao, J., Tie, X., Molina, L. T., Li, G. 2020; 117 (18): 9755-9761


    Aerosol-radiation interaction (ARI) plays a significant role in the accumulation of fine particulate matter (PM2.5) by stabilizing the planetary boundary layer and thus deteriorating air quality during haze events. However, modification of photolysis by aerosol scattering or absorbing solar radiation (aerosol-photolysis interaction or API) alters the atmospheric oxidizing capacity, decreases the rate of secondary aerosol formation, and ultimately alleviates the ARI effect on PM2.5 pollution. Therefore, the synergetic effect of both ARI and API can either aggravate or even mitigate PM2.5 pollution. To test the effect, a fully coupled Weather Research and Forecasting (WRF)-Chem model has been used to simulate a heavy haze episode in North China Plain. Our results show that ARI contributes to a 7.8% increase in near-surface PM2.5 However, API suppresses secondary aerosol formation, and the combination of ARI and API results in only 4.8% net increase of PM2.5 Additionally, API increases the solar radiation reaching the surface and perturbs aerosol nucleation and activation to form cloud condensation nuclei, influencing aerosol-cloud interaction. The results suggest that API reduces PM2.5 pollution during haze events, but adds uncertainties in climate prediction.

    View details for DOI 10.1073/pnas.1916775117

    View details for PubMedID 32300007

    View details for PubMedCentralID PMC7211923

  • Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari-8 Using In Situ Aircraft Measurements Over the Southern Ocean EARTH AND SPACE SCIENCE Zhao, L., Zhao, C., Wang, Y., Wang, Y., Ya, Y. 2020; 7 (5)
  • Impact of Cloud Ice Particle Size Uncertainty in a Climate Model and Implications for Future Satellite Missions JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Wang, Y., Su, H., Jiang, J. H., Xu, F., Yung, Y. L. 2020; 125 (6)
  • Investigation of aerosol-cloud interactions under different absorptive aerosol regimes using Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) ground-based measurements ATMOSPHERIC CHEMISTRY AND PHYSICS Zheng, X., Xi, B., Dong, X., Logan, T., Wang, Y., Wu, P. 2020; 20 (6): 3483-3501
  • Spatiotemporal Variations of Precipitation in China Using Surface Gauge Observations from 1961 to 2016 ATMOSPHERE Su, Y., Zhao, C., Wang, Y., Ma, Z. 2020; 11 (3)
  • An unexpected catalyst dominates formation and radiative forcing of regional haze PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhang, F., Wang, Y., Peng, J., Chen, L., Sun, Y., Duan, L., Ge, X., Li, Y., Zhao, J., Liu, C., Zhang, X., Zhang, G., Pan, Y., Wang, Y., Zhang, A. L., Ji, Y., Wang, G., Hu, M., Molina, M. J., Zhang, R. 2020; 117 (8): 3960-3966


    Although regional haze adversely affects human health and possibly counteracts global warming from increasing levels of greenhouse gases, the formation and radiative forcing of regional haze on climate remain uncertain. By combining field measurements, laboratory experiments, and model simulations, we show a remarkable role of black carbon (BC) particles in driving the formation and trend of regional haze. Our analysis of long-term measurements in China indicates declined frequency of heavy haze events along with significantly reduced SO2, but negligibly alleviated haze severity. Also, no improving trend exists for moderate haze events. Our complementary laboratory experiments demonstrate that SO2 oxidation is efficiently catalyzed on BC particles in the presence of NO2 and NH3, even at low SO2 and intermediate relative humidity levels. Inclusion of the BC reaction accounts for about 90-100% and 30-50% of the sulfate production during moderate and heavy haze events, respectively. Calculations using a radiative transfer model and accounting for the sulfate formation on BC yield an invariant radiative forcing of nearly zero W m-2 on the top of the atmosphere throughout haze development, indicating small net climatic cooling/warming but large surface cooling, atmospheric heating, and air stagnation. This BC catalytic chemistry facilitates haze development and explains the observed trends of regional haze in China. Our results imply that reduction of SO2 alone is insufficient in mitigating haze occurrence and highlight the necessity of accurate representation of the BC chemical and radiative properties in predicting the formation and assessing the impacts of regional haze.

    View details for DOI 10.1073/pnas.1919343117

    View details for Web of Science ID 000516771500017

    View details for PubMedID 32041887

    View details for PubMedCentralID PMC7049161

  • Remarkable nucleation and growth of ultrafine particles from vehicular exhaust. Proceedings of the National Academy of Sciences of the United States of America Guo, S., Hu, M., Peng, J., Wu, Z., Zamora, M. L., Shang, D., Du, Z., Zheng, J., Fang, X., Tang, R., Wu, Y., Zeng, L., Shuai, S., Zhang, W., Wang, Y., Ji, Y., Li, Y., Zhang, A. L., Wang, W., Zhang, F., Zhao, J., Gong, X., Wang, C., Molina, M. J., Zhang, R. 2020; 117 (7): 3427-3432


    High levels of ultrafine particles (UFPs; diameter of less than 50 nm) are frequently produced from new particle formation under urban conditions, with profound implications on human health, weather, and climate. However, the fundamental mechanisms of new particle formation remain elusive, and few experimental studies have realistically replicated the relevant atmospheric conditions. Previous experimental studies simulated oxidation of one compound or a mixture of a few compounds, and extrapolation of the laboratory results to chemically complex air was uncertain. Here, we show striking formation of UFPs in urban air from combining ambient and chamber measurements. By capturing the ambient conditions (i.e., temperature, relative humidity, sunlight, and the types and abundances of chemical species), we elucidate the roles of existing particles, photochemistry, and synergy of multipollutants in new particle formation. Aerosol nucleation in urban air is limited by existing particles but negligibly by nitrogen oxides. Photooxidation of vehicular exhaust yields abundant precursors, and organics, rather than sulfuric acid or base species, dominate formation of UFPs under urban conditions. Recognition of this source of UFPs is essential to assessing their impacts and developing mitigation policies. Our results imply that reduction of primary particles or removal of existing particles without simultaneously limiting organics from automobile emissions is ineffective and can even exacerbate this problem.

    View details for DOI 10.1073/pnas.1916366117

    View details for PubMedID 32015109

    View details for PubMedCentralID PMC7035480

  • Reduced European aerosol emissions suppress winter extremes over northern Eurasia NATURE CLIMATE CHANGE Wang, Y., Le, T., Chen, G., Yung, Y. L., Su, H., Seinfeld, J. H., Jiang, J. H. 2020; 10 (3): 225-+
  • East Asian Study of Tropospheric Aerosols and their Impact on Regional Clouds, Precipitation, and Climate (EAST-AIR<sub>CPC</sub>) JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Li, Z., Wang, Y., Guo, J., Zhao, C., Cribb, M., Dong, X., Fan, J., Gong, D., Huang, J., Jiang, M., Jiang, Y., Lee, S., Li, H., Li, J., Liu, J., Qian, Y., Rosenfeld, D., Shan, S., Sun, Y., Wang, H., Xin, J., Yan, X., Yang, X., Yang, X., Zhang, F., Zheng, Y. 2019; 124 (23): 13026-13054
  • Climate Impacts of the Biomass Burning in Indochina on Atmospheric Conditions over Southern China AEROSOL AND AIR QUALITY RESEARCH Huang, L., Lin, W., Li, F., Wang, Y., Jiang, B. 2019; 19 (12): 2707-2720
  • The climatology and trend of black carbon in China from 12-year ground observations CLIMATE DYNAMICS Zhang, Y., Li, Y., Guo, J., Wang, Y., Chen, D., Chen, H. 2019; 53 (9-10): 5881-5892
  • Interpretation of the Top-of-Atmosphere Energy Flux for Future Arctic Warming SCIENTIFIC REPORTS Hwang, J., Choi, Y., Yoo, C., Wang, Y., Su, H., Jiang, J. H. 2019; 9: 13059


    With the trend of amplified warming in the Arctic, we examine the observed and modeled top-of-atmosphere (TOA) radiative responses to surface air-temperature changes over the Arctic by using TOA energy fluxes from NASA's CERES observations and those from twelve climate models in CMIP5. Considerable inter-model spreads in the radiative responses suggest that future Arctic warming may be determined by the compensation between the radiative imbalance and poleward energy transport (mainly via transient eddy activities). The poleward energy transport tends to prevent excessive Arctic warming: the transient eddy activities are weakened because of the reduced meridional temperature gradient under polar amplification. However, the models that predict rapid Arctic warming do not realistically simulate the compensation effect. This role of energy compensation in future Arctic warming is found only when the inter-model differences in cloud radiative effects are considered. Thus, the dynamical response can act as a buffer to prevent excessive Arctic warming against the radiative response of 0.11 W m-2 K-1 as measured from satellites, which helps the Arctic climate system retain an Arctic climate sensitivity of 4.61 K. Therefore, if quantitative analyses of the observations identify contribution of atmospheric dynamics and cloud effects to radiative imbalance, the satellite-measured radiative response will be a crucial indicator of future Arctic warming.

    View details for DOI 10.1038/s41598-019-49218-6

    View details for Web of Science ID 000484988100033

    View details for PubMedID 31506462

    View details for PubMedCentralID PMC6736793

  • Relationships Between Tropical Ascent and High Cloud Fraction Changes With Warming Revealed by Perturbation Physics Experiments in CAM5 GEOPHYSICAL RESEARCH LETTERS Schiro, K. A., Su, H., Wang, Y., Langenbrunner, B., Jiang, J. H., Neelin, J. 2019; 46 (16): 10112-10121
  • Inducing Factors and Impacts of the October 2017 California Wildfires EARTH AND SPACE SCIENCE Li, A. X., Wang, Y., Yung, Y. L. 2019; 6 (8): 1480-1488
  • Ice nucleation by aerosols from anthropogenic pollution NATURE GEOSCIENCE Zhao, B., Wang, Y., Gu, Y., Liou, K., Jiang, J. H., Fan, J., Liu, X., Huang, L., Yung, Y. L. 2019; 12 (8): 602-+


    The formation of ice particles in the atmosphere strongly affects cloud properties and the climate. While mineral dust is known to be an effective ice nucleating particle, the role of aerosols from anthropogenic pollution in ice nucleation is still under debate. Here we probe the ice nucleation ability of different aerosol types by combining 11-year observations from multiple satellites and cloud-resolving model simulations. We find that, for strong convective systems, ice particle effective radius near cloud top decreases with increasing loading of polluted continental aerosols, because the ice formation is dominated by homogeneous freezing of cloud droplets that are smaller under more polluted conditions. In contrast, an increase in ice particle effective radius with polluted continental aerosols is found for moderate convection. Our model simulations suggest that this positive correlation is explained by enhanced heterogeneous ice nucleation and prolonged ice particle growth at larger aerosol loading, indicating that polluted continental aerosols contain a significant fraction of ice nucleating particles. Similar aerosol-ice relationships are observed for dust aerosols, further corroborating the ice nucleation ability of polluted continental aerosols. By catalyzing ice formation, aerosols from anthropogenic pollution could have profound impacts on cloud lifetime and radiative effect as well as precipitation efficiency.

    View details for DOI 10.1038/s41561-019-0389-4

    View details for Web of Science ID 000477864200008

    View details for PubMedID 31360220

    View details for PubMedCentralID PMC6662716

  • Modeling Study of the Air Quality Impact of Record-Breaking Southern California Wildfires in December 2017 JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Shi, H., Jiang, Z., Zhao, B., Li, Z., Chen, Y., Gu, Y., Jiang, J. H., Lee, M., Liou, K., Neu, J. L., Payne, V. H., Su, H., Wang, Y., Witek, M., Worden, J. 2019; 124 (12): 6554-6570


    We investigate the air quality impact of record-breaking wildfires in Southern California during 5-18 December 2017 using the Weather Research and Forecasting model with Chemistry in combination with satellite and surface observations. This wildfire event was driven by dry and strong offshore Santa Ana winds, which played a critical role in fire formation and air pollutant transport. By utilizing fire emissions derived from the high-resolution (375 × 375 m2) Visible Infrared Imaging Radiometer Suite active fire detections, the simulated magnitude and temporal evolution of fine particulate matter (PM2.5) concentrations agree reasonably well with surface observations (normalized mean bias = 4.0%). Meanwhile, the model could generally capture the spatial pattern of aerosol optical depth from satellite observations. Sensitivity tests reveal that using a high spatial resolution for fire emissions and a reasonable treatment of plume rise (a fair split between emissions injected at surface and those lifted to upper levels) is important for achieving decent PM2.5 simulation results. Biases in PM2.5 simulation are relatively large (about 50%) during the period with the strongest Santa Ana wind, due to a possible underestimation of burning area and uncertainty in wind field variation. The 2017 December fire event increases the 14-day averaged PM2.5 concentrations by up to 231.2 μg/m3 over the downwind regions, which substantially exceeds the U.S. air quality standards, potentially leading to adverse health impacts. The human exposure to fire-induced PM2.5 accounts for 14-42% of the annual total PM2.5 exposure in areas impacted by the fire plumes.

    View details for DOI 10.1029/2019JD030472

    View details for Web of Science ID 000477800000039

    View details for PubMedID 32455093

    View details for PubMedCentralID PMC7243153

  • Interaction between succinic acid and sulfuric acid-base clusters ATMOSPHERIC CHEMISTRY AND PHYSICS Lin, Y., Ji, Y., Li, Y., Secrest, J., Xu, W., Xu, F., Wang, Y., An, T., Zhang, R. 2019; 19 (12): 8003-8019
  • Impacts of household sources on air pollution at village and regional scales in India ATMOSPHERIC CHEMISTRY AND PHYSICS Rooney, B., Zhao, R., Wang, Y., Bates, K. H., Pillarisetti, A., Sharma, S., Kundu, S., Bond, T. C., Lam, N. L., Ozaltun, B., Xu, L., Goel, V., Fleming, L. T., Weltman, R., Meinardi, S., Blake, D. R., Nizkorodov, S. A., Edwards, R. D., Yadav, A., Arora, N. K., Smith, K. R., Seinfeld, J. H. 2019; 19 (11): 7719-7742
  • Non-Monotonic Aerosol Effect on Precipitation in Convective Clouds over Tropical Oceans SCIENTIFIC REPORTS Liu, H., Guo, J., Koren, I., Altaratz, O., Dagan, G., Wang, Y., Jiang, J. H., Zhai, P., Yung, Y. L. 2019; 9: 7809


    Aerosol effects on convective clouds and associated precipitation constitute an important open-ended question in climate research. Previous studies have linked an increase in aerosol concentration to a delay in the onset of rain, invigorated clouds and stronger rain rates. Here, using observational data, we show that the aerosol effect on convective clouds shifts from invigoration to suppression with increasing aerosol optical depth. We explain this shift in trend (using a cloud model) as the result of a competition between two types of microphysical processes: cloud-core-based invigorating processes vs. peripheral suppressive processes. We show that the aerosol optical depth value that marks the shift between invigoration and suppression depends on the environmental thermodynamic conditions. These findings can aid in better parameterizing aerosol effects in climate models for the prediction of climate trends.

    View details for DOI 10.1038/s41598-019-44284-2

    View details for Web of Science ID 000468859400024

    View details for PubMedID 31127137

    View details for PubMedCentralID PMC6534586

  • Declining diurnal temperature range in the North China Plain related to environmental changes CLIMATE DYNAMICS Xue, W., Guo, J., Zhang, Y., Zhou, S., Wang, Y., Miao, Y., Liu, L., Xu, H., Li, J., Chen, D., Liu, H. 2019; 52 (9-10): 6109-6119
  • Optical Properties and Radiative Forcing of Aged BC due to Hygroscopic Growth: Effects of the Aggregate Structure JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Zeng, C., Liu, C., Li, J., Zhu, B., Yin, Y., Wang, Y. 2019; 124 (8): 4620-4633
  • Estimating the Contribution of Local Primary Emissions to Particulate Pollution Using High-Density Station Observations JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Zhao, C., Wang, Y., Shi, X., Zhang, D., Wang, C., Jiang, J. H., Zhang, Q., Fan, H. 2019; 124 (3): 1648-1661
  • Formation and Optical Properties of Brown Carbon from Small α-Dicarbonyls and Amines ENVIRONMENTAL SCIENCE & TECHNOLOGY Marrero-Ortiz, W., Hu, M., Du, Z., Ji, Y., Wang, Y., Guo, S., Lin, Y., Gomez-Hermandez, M., Peng, J., Li, Y., Secrest, J., Zamora, M. L., Wang, Y., An, T., Zhang, R. 2019; 53 (1): 117-126


    Brown Carbon (BrC) aerosols scatter and absorb solar radiation, directly affecting the Earth's radiative budget. However, considerable uncertainty exists concerning the chemical mechanism leading to BrC formation and their optical properties. In this work, BrC particles were prepared from mixtures of small α-dicarbonyls (glyoxal and methylglyoxal) and amines (methylamine, dimethylamine, and trimethylamine). The absorption and scattering of BrC particles were measured using a photoacoustic extinctometer (405 and 532 nm), and the chemical composition of the α-dicarbonyl-amine mixtures was analyzed using orbitrap-mass spectrometry and thermal desorption-ion drift-chemical ionization mass spectrometry. The single scattering albedo for methylglyoxal-amine mixtures is smaller than that of glyoxal-amine mixtures and increases with the methyl substitution of amines. The mass absorption cross-section for methylglyoxal-amine mixtures is two times higher at 405 nm wavelength than that at 532 nm wavelength. The derived refractive indexes at the 405 nm wavelength are 1.40-1.64 for the real part and 0.002-0.195 for the imaginary part. Composition analysis in the α-dicarbonyl-amine mixtures reveals N-heterocycles as the dominant products, which are formed via multiple steps involving nucleophilic attack, steric hindrance, and dipole-dipole interaction between α-dicarbonyls and amines. BrC aerosols, if formed from the particle-phase reaction of methylglyoxal with methylamine, likely contribute to atmospheric warming.

    View details for DOI 10.1021/acs.est.8b03995

    View details for Web of Science ID 000455076600013

    View details for PubMedID 30499298

  • Increased Frequency of Extreme Tropical Deep Convection: AIRS Observations and Climate Model Predictions GEOPHYSICAL RESEARCH LETTERS Aumann, H. H., Behrangi, A., Wang, Y. 2018; 45 (24): 13530-13537
  • Change in household fuels dominates the decrease in PM<sub>2.5</sub> exposure and premature mortality in China in 2005-2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhao, B., Zheng, H., Wang, S., Smith, K. R., Lu, X., Aunan, K., Gu, Y., Wang, Y., Ding, D., Xing, J., Fu, X., Yang, X., Liou, K., Hao, J. 2018; 115 (49): 12401-12406


    To tackle the severe fine particle (PM2.5) pollution in China, the government has implemented stringent control policies mainly on power plants, industry, and transportation since 2005, but estimates of the effectiveness of the policy and the temporal trends in health impacts are subject to large uncertainties. By adopting an integrated approach that combines chemical transport simulation, ambient/household exposure evaluation, and health-impact assessment, we find that the integrated population-weighted exposure to PM2.5 (IPWE) decreased by 47% (95% confidence interval, 37-55%) from 2005 [180 (146-219) μg/m3] to 2015 [96 (83-111) μg/m3]. Unexpectedly, 90% (86-93%) of such reduction is attributed to reduced household solid-fuel use, primarily resulting from rapid urbanization and improved incomes rather than specific control policies. The IPWE due to household fuels for both cooking and heating decreased, but the impact of cooking is significantly larger. The reduced household-related IPWE is estimated to avoid 0.40 (0.25-0.57) million premature deaths annually, accounting for 33% of the PM2.5-induced mortality in 2015. The IPWE would be further reduced by 63% (57-68%) if the remaining household solid fuels were replaced by clean fuels, which would avoid an additional 0.51 (0.40-0.64) million premature deaths. Such a transition to clean fuels, especially for heating, requires technology innovation and policy support to overcome the barriers of high cost of distribution systems, as is recently being attempted in the Beijing-Tianjin-Hebei area. We suggest that household-fuel use be more highly prioritized in national control policies, considering its effects on PM2.5 exposures.

    View details for DOI 10.1073/pnas.1812955115

    View details for Web of Science ID 000452124700037

    View details for PubMedID 30455309

    View details for PubMedCentralID PMC6298076

  • Source contributions and potential reductions to health effects of particulate matter in India ATMOSPHERIC CHEMISTRY AND PHYSICS Guo, H., Kota, S., Chen, K., Sahu, S., Hu, J., Ying, Q., Wang, Y., Zhang, H. 2018; 18 (20): 15219-15229
  • Constraining Aging Processes of Black Carbon in the Community Atmosphere Model Using Environmental Chamber Measurements JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS Wang, Y., Ma, P., Peng, J., Zhang, R., Jiang, J. H., Easter, R. C., Yung, Y. L. 2018; 10 (10): 2514-2526


    The direct radiative forcing of black carbon aerosol (BC) on the Earth system remains unsettled, largely due to the uncertainty with physical properties of BC throughout their lifecycle. Here we show that ambient chamber measurements of BC properties provide a novel constraint on the crude BC aging representation in climate models. Observational evidence for significant absorption enhancement of BC can be reproduced when the aging processes in the four-mode version of the Modal Aerosol Module (MAM4) aerosol scheme in the Community Atmosphere Model version 5 are calibrated by the recent in situ chamber measurements. An observation-based scaling method is developed in the aging timescale calculation to alleviate the influence of biases in the simulated model chemical composition. Model sensitivity simulations suggest that the different monolayer settings in the BC aging parameterization of MAM4 can cause as large as 26% and 24% differences in BC burden and radiative forcing, respectively. We also find that an increase in coating materials (e.g., sulfate and secondary organic aerosols) reduces BC lifetime by increasing the hygroscopicity of the mixture but enhances its absorption, resulting in a net increase in BC direct radiative forcing. Our results suggest that accurate simulations of BC aging processes as well as other aerosol species are equally important in reducing the uncertainty of BC forcing estimation.

    View details for DOI 10.1029/2018MS001387

    View details for Web of Science ID 000450413200008

    View details for PubMedID 31031881

    View details for PubMedCentralID PMC6472719

  • Contrasting effects on deep convective clouds by different types of aerosols NATURE COMMUNICATIONS Jiang, J. H., Su, H., Huang, L., Wang, Y., Massie, S., Zhao, B., Omar, A., Wang, Z. 2018; 9: 3874


    Convective clouds produce a significant proportion of the global precipitation and play an important role in the energy and water cycles. We quantify changes of the convective cloud ice mass-weighted altitude centroid (ZIWC) as a function of aerosol optical thickness (AOT). Analyses are conducted in smoke, dust and polluted continental aerosol environments over South America, Central Africa and Southeast Asia, using the latest measurements from the CloudSat and CALIPSO satellites. We find aerosols can inhibit or invigorate convection, depending on aerosol type and concentration. On average, smoke tends to suppress convection and results in lower ZIWC than clean clouds. Polluted continental aerosol tends to invigorate convection and promote higher ZIWC. The dust aerosol effects are regionally dependent and their signs differ from place to place. Moreover, we find that the aerosol inhibition or invigoration effects do not vary monotonically with AOT and the variations depend strongly on aerosol type. Our observational findings indicate that aerosol type is one of the key factors in determining the aerosol effects on convective clouds.

    View details for DOI 10.1038/s41467-018-06280-4

    View details for Web of Science ID 000445329000009

    View details for PubMedID 30250192

    View details for PubMedCentralID PMC6155150

  • Impacts of Saharan Dust on Atlantic Regional Climate and Implications for Tropical Cyclones JOURNAL OF CLIMATE Pan, B., Wang, Y., Hu, J., Lin, Y., Hsieh, J., Logan, T., Feng, X., Jiang, J. H., Yung, Y. L., Zhang, R. 2018; 31 (18): 7621-7644
  • Enlarging Rainfall Area of Tropical Cyclones by Atmospheric Aerosols GEOPHYSICAL RESEARCH LETTERS Zhao, C., Lin, Y., Wu, F., Wang, Y., Li, Z., Rosenfeld, D., Wang, Y. 2018; 45 (16): 8604-8611
  • Particle acidity and sulfate production during severe haze events in China cannot be reliably inferred by assuming a mixture of inorganic salts ATMOSPHERIC CHEMISTRY AND PHYSICS Wang, G., Zhang, F., Peng, J., Duan, L., Ji, Y., Marrero-Ortiz, W., Wang, J., Li, J., Wu, C., Cao, C., Wang, Y., Zheng, J., Secrest, J., Li, Y., Wang, Y., Li, H., Li, N., Zhang, R. 2018; 18 (14): 10123-10132
  • Radiative absorption enhancement of dust mixed with anthropogenic pollution over East Asia ATMOSPHERIC CHEMISTRY AND PHYSICS Tian, P., Zhang, L., Ma, J., Tang, K., Xu, L., Wang, Y., Cao, X., Liang, J., Ji, Y., Jiang, J. H., Yung, Y. L., Zhang, R. 2018; 18 (11): 7815-7825
  • Year-long simulation of gaseous and particulate air pollutants in India ATMOSPHERIC ENVIRONMENT Kota, H., Guo, H., Myllyvirta, L., Hu, J., Sahu, S., Garaga, R., Ying, Q., Gao, A., Dahiya, S., Wang, Y., Zhang, H. 2018; 180: 244-255
  • Type-Dependent Responses of Ice Cloud Properties to Aerosols From Satellite Retrievals GEOPHYSICAL RESEARCH LETTERS Zhao, B., Gu, Y., Liou, K., Wang, Y., Liu, X., Huang, L., Jiang, J. H., Su, H. 2018; 45 (7): 3297-3306


    Aerosol-cloud interactions represent one of the largest uncertainties in external forcings on our climate system. Compared with liquid clouds, the observational evidence for the aerosol impact on ice clouds is much more limited and shows conflicting results, partly because the distinct features of different ice cloud and aerosol types were seldom considered. Using 9-year satellite retrievals, we find that, for convection-generated (anvil) ice clouds, cloud optical thickness, cloud thickness, and cloud fraction increase with small-to-moderate aerosol loadings (<0.3 aerosol optical depth) and decrease with further aerosol increase. For in situ formed ice clouds, however, these cloud properties increase monotonically and more sharply with aerosol loadings. An increase in loading of smoke aerosols generally reduces cloud optical thickness of convection-generated ice clouds, while the reverse is true for dust and anthropogenic pollution aerosols. These relationships between different cloud/aerosol types provide valuable constraints on the modeling assessment of aerosol-ice cloud radiative forcing.

    View details for DOI 10.1002/2018GL077261

    View details for Web of Science ID 000435743400048

    View details for PubMedID 31631917

    View details for PubMedCentralID PMC6800730

  • Application and Evaluation of an Explicit Prognostic Cloud-Cover Scheme in GRAPES Global Forecast System JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS Ma, Z., Liu, Q., Zhao, C., Shen, X., Wang, Y., Jiang, J. H., Li, Z., Yung, Y. 2018; 10 (3): 652-667
  • Aerosol microphysical and radiative effects on continental cloud ensembles ADVANCES IN ATMOSPHERIC SCIENCES Wang, Y., Vogel, J. M., Lin, Y., Pan, B., Hu, J., Liu, Y., Dong, X., Jiang, J. H., Yung, Y. L., Zhang, R. 2018; 35 (2): 234-247
  • Elucidating the Role of Anthropogenic Aerosols in Arctic Sea Ice Variations JOURNAL OF CLIMATE Wang, Y., Jiang, J. H., Su, H., Choi, Y., Huang, L., Guo, J., Yung, Y. L. 2018; 31 (1): 99-114
  • Trans-Pacific transport of dust aerosols from East Asia: Insights gained from multiple observations and modeling ENVIRONMENTAL POLLUTION Guo, J., Lou, M., Miao, Y., Wang, Y., Zeng, Z., Liu, H., He, J., Xu, H., Wang, F., Min, M., Zhai, P. 2017; 230: 1030-1039


    East Asia is one of the world's largest sources of dust and anthropogenic pollution. Dust particles originating from East Asia have been recognized to travel across the Pacific to North America and beyond, thereby affecting the radiation incident on the surface as well as clouds aloft in the atmosphere. In this study, integrated analyses are performed focusing on one trans-Pacific dust episode during 12-22 March 2015, based on space-borne, ground-based observations, reanalysis data combined with Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), and the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem). From the perspective of synoptic patterns, the location and strength of Aleutian low pressure system largely determined the eastward transport of dust plumes towards western North America. Multi-sensor satellite observations reveal that dust aerosols in this episode originated from the Taklimakan and Gobi Deserts. Moreover, the satellite observations suggest that the dust particles can be transformed to polluted particles over the East Asian regions after encountering high concentration of anthropogenic pollutants. In terms of the vertical distribution of polluted dust particles, at the very beginning, they were mainly located in the altitudes ranging from 1 km to 7 km over the source region, then ascended to 2 km-9 km over the Pacific Ocean. The simulations confirm that these elevated dust particles in the lower free troposphere were largely transported along the prevailing westerly jet stream. Overall, observations and modeling demonstrate how a typical springtime dust episode develops and how the dust particles travel over the North Pacific Ocean all the way to North America.

    View details for DOI 10.1016/j.envpol.2017.07.062

    View details for Web of Science ID 000412250900107

    View details for PubMedID 28764119

  • The blue skies in Beijing during APEC 2014: A quantitative assessment of emission control efficiency and meteorological influence ATMOSPHERIC ENVIRONMENT Liu, H., He, J., Guo, J., Miao, Y., Yin, J., Wang, Y., Xu, H., Liu, H., Yan, Y., Li, Y., Zhai, P. 2017; 167: 235-244
  • Warming effect of dust aerosols modulated by overlapping clouds below ATMOSPHERIC ENVIRONMENT Xu, H., Guo, J., Wang, Y., Zhao, C., Zhang, Z., Min, M., Miao, Y., Liu, H., He, J., Zhou, S., Zhai, P. 2017; 166: 393-402
  • Cloud-resolving model intercomparison of an MC3E squall line case: Part I-Convective updrafts JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Fan, J., Han, B., Varble, A., Morrison, H., North, K., Kollias, P., Chen, B., Dong, X., Giangrande, S. E., Khain, A., Lin, Y., Mansell, E., Milbrandt, J. A., Stenz, R., Thompson, G., Wang, Y. 2017; 122 (17): 9351-9378
  • Reassessing the atmospheric oxidation mechanism of toluene PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ji, Y., Zhao, J., Terazono, H., Misawa, K., Levitt, N. P., Li, Y., Lin, Y., Peng, J., Wang, Y., Duan, L., Pan, B., Zhang, F., Feng, X., An, T., Marrero-Ortiz, W., Secrest, J., Zhang, A. L., Shibuya, K., Molina, M. J., Zhang, R. 2017; 114 (31): 8169-8174


    Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH (ortho) addition, the pathway of H extraction by O2 to form the cresol proceeds with a smaller barrier than O2 addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.

    View details for DOI 10.1073/pnas.1705463114

    View details for Web of Science ID 000406653300036

    View details for PubMedID 28716940

    View details for PubMedCentralID PMC5547634

  • The linkage between stratospheric water vapor and surface temperature in an observation-constrained coupled general circulation model CLIMATE DYNAMICS Wang, Y., Su, H., Jiang, J. H., Livesey, N. J., Santee, M. L., Froidevaux, L., Read, W. G., Anderson, J. 2017; 48 (7-8): 2671-2683
  • Aerosol vertical distribution and optical properties over China from long-term satellite and ground-based remote sensing ATMOSPHERIC CHEMISTRY AND PHYSICS Tian, P., Cao, X., Zhang, L., Sun, N., Sun, L., Logan, T., Shi, J., Wang, Y., Ji, Y., Lin, Y., Huang, Z., Zhou, T., Shi, Y., Zhang, R. 2017; 17 (4): 2509-2523
  • Overview of Persistent Haze Events in China AIR POLLUTION IN EASTERN ASIA: AN INTEGRATED PERSPECTIVE Zhang, R., Tian, P., Ji, Y., Lin, Y., Peng, J., Pan, B., Wang, Y., Wang, G., Li, G., Wang, W., Zhang, F., Feng, X., Duan, L., Hu, J., Marrero-Ortiz, W., Secrest, J., Hu, M., Bouarar, Wang, Brasseur, G. P. 2017; 16: 3-25
  • Aerosol and monsoon climate interactions over Asia REVIEWS OF GEOPHYSICS Li, Z., Lau, W., Ramanathan, V., Wu, G., Ding, Y., Manoj, M. G., Liu, J., Qian, Y., Li, J., Zhou, T., Fan, J., Rosenfeld, D., Ming, Y., Wang, Y., Huang, J., Wang, B., Xu, X., Lee, S., Cribb, M., Zhang, F., Yang, X., Zhao, C., Takemura, T., Wang, K., Xia, X., Yin, Y., Zhang, H., Guo, J., Zhai, P. M., Sugimoto, N., Babu, S. S., Brasseur, G. P. 2016; 54 (4): 866-929
  • Persistent sulfate formation from London Fog to Chinese haze PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wang, G., Zhang, R., Gomez, M. E., Yang, L., Zamora, M., Hu, M., Lin, Y., Peng, J., Guo, S., Meng, J., Li, J., Cheng, C., Hu, T., Ren, Y., Wang, Y., Gao, J., Cao, J., An, Z., Zhou, W., Li, G., Wang, J., Tian, P., Marrero-Ortiz, W., Secrest, J., Du, Z., Zheng, J., Shang, D., Zeng, L., Shao, M., Wang, W., Huang, Y., Wang, Y., Zhu, Y., Li, Y., Hu, J., Pan, B., Cai, L., Cheng, Y., Ji, Y., Zhang, F., Rosenfeld, D., Liss, P. S., Duce, R. A., Kolb, C. E., Molina, M. J. 2016; 113 (48): 13630-13635


    Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.

    View details for DOI 10.1073/pnas.1616540113

    View details for Web of Science ID 000388835700047

    View details for PubMedID 27849598

    View details for PubMedCentralID PMC5137769

  • Review of Aerosol-Cloud Interactions: Mechanisms, Significance, and Challenges JOURNAL OF THE ATMOSPHERIC SCIENCES Fan, J., Wang, Y., Rosenfeld, D., Liu, X. 2016; 73 (11): 4221-4252
  • Distinct Impacts of Aerosols on an Evolving Continental Cloud Complex during the RACORO Field Campaign JOURNAL OF THE ATMOSPHERIC SCIENCES Lin, Y., Wang, Y., Pan, B., Hu, J., Liu, Y., Zhang, R. 2016; 73 (9): 3681-3700
  • Rate and timescale of black carbon aging regulate direct radiative forcing PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhang, R., Peng, J., Wang, Y., Hu, M. 2016; 113 (35): E5094-E5095

    View details for DOI 10.1073/pnas.1610241113

    View details for Web of Science ID 000383090700002

    View details for PubMedID 27555593

    View details for PubMedCentralID PMC5024605

  • Global climate models intercomparison of anthropogenic aerosols effects on regional climate over north Pacific Hu, J., Zhang, R., Pan, B., Lin, Y., Wang, Y., Ming, Y. AMER CHEMICAL SOC. 2016
  • Interactions between precipitation, lightning activity and anthropogenic aerosols over Houston, Texas Lin, Y., Wang, Y., Orville, R., Zhang, R. AMER CHEMICAL SOC. 2016
  • Impacts of Saharan dust on the genesis and evolution of Hurricane Earl (2010) Pan, B., Zhang, R., Wang, Y., Lin, Y., Hu, J., Hsieh, J. AMER CHEMICAL SOC. 2016
  • Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments Peng, J., Hu, M., Guo, S., Du, Z., Zheng, J., Shang, D., Zamora, M., Zeng, L., Shao, M., Wu, Y., Zheng, J., Wang, Y., Glen, C., Collins, D., Molina, M., Zhang, R. AMER CHEMICAL SOC. 2016
  • Aerosol-cloud-climate interactions from a modeling perspective Wang, Y. AMER CHEMICAL SOC. 2016
  • Toward reconciling the influence of atmospheric aerosols and greenhouse gases on light precipitation changes in Eastern China JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Wang, Y., Ma, P., Jiang, J. H., Su, H., Rasch, P. J. 2016; 121 (10): 5878-5887
  • Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Peng, J., Hu, M., Guo, S., Du, Z., Zheng, J., Shang, D., Zamora, M., Zeng, L., Shao, M., Wu, Y., Zheng, J., Wang, Y., Glen, C. R., Collins, D. R., Molina, M. J., Zhang, R. 2016; 113 (16): 4266-4271


    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

    View details for DOI 10.1073/pnas.1602310113

    View details for Web of Science ID 000374393800030

    View details for PubMedID 27035993

    View details for PubMedCentralID PMC4843448

  • Air Pollution or Global Warming: Attribution of Extreme Precipitation Changes in Eastern China-Comments on "Trends of Extreme Precipitation in Eastern China and Their Possible Causes" ADVANCES IN ATMOSPHERIC SCIENCES Wang, Y. 2015; 32 (10): 1444-1446
  • Atmospheric responses to the redistribution of anthropogenic aerosols JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Wang, Y., Jiang, J. H., Su, H. 2015; 120 (18): 9625-9641
  • Formation of Urban Fine Particulate Matter CHEMICAL REVIEWS Zhang, R., Wang, G., Guo, S., Zarnora, M. L., Ying, Q., Lin, Y., Wang, W., Hu, M., Wang, Y. 2015; 115 (10): 3803-3855

    View details for DOI 10.1021/acs.chemrev.5b00067

    View details for Web of Science ID 000355383900005

    View details for PubMedID 25942499

  • Measurements of nitrous acid (HONO) using ion drift-chemical ionization mass spectrometry during the 2009 SHARP field campaign ATMOSPHERIC ENVIRONMENT Levy, M., Zhang, R., Zheng, J., Zhang, A. L., Xu, W., Gomez-Hernandez, M., Wang, Y., Olaguer, E. 2014; 94: 231-240
  • Assessing the effects of anthropogenic aerosols on Pacific storm track using a multiscale global climate model PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wang, Y., Wang, M., Zhang, R., Ghan, S. J., Lin, Y., Hu, J., Pan, B., Levy, M., Jiang, J. H., Molina, M. J. 2014; 111 (19): 6894-6899


    Atmospheric aerosols affect weather and global general circulation by modifying cloud and precipitation processes, but the magnitude of cloud adjustment by aerosols remains poorly quantified and represents the largest uncertainty in estimated forcing of climate change. Here we assess the effects of anthropogenic aerosols on the Pacific storm track, using a multiscale global aerosol-climate model (GCM). Simulations of two aerosol scenarios corresponding to the present day and preindustrial conditions reveal long-range transport of anthropogenic aerosols across the north Pacific and large resulting changes in the aerosol optical depth, cloud droplet number concentration, and cloud and ice water paths. Shortwave and longwave cloud radiative forcing at the top of atmosphere are changed by -2.5 and +1.3 W m(-2), respectively, by emission changes from preindustrial to present day, and an increased cloud top height indicates invigorated midlatitude cyclones. The overall increased precipitation and poleward heat transport reflect intensification of the Pacific storm track by anthropogenic aerosols. Hence, this work provides, for the first time to the authors' knowledge, a global perspective of the effects of Asian pollution outflows from GCMs. Furthermore, our results suggest that the multiscale modeling framework is essential in producing the aerosol invigoration effect of deep convective clouds on a global scale.

    View details for DOI 10.1073/pnas.1403364111

    View details for Web of Science ID 000335798000044

    View details for PubMedID 24733923

    View details for PubMedCentralID PMC4024913

  • Distinct effects of anthropogenic aerosols on tropical cyclones NATURE CLIMATE CHANGE Wang, Y., Lee, K., Lin, Y., Levy, M., Zhang, R. 2014; 4 (5): 368-373
  • Measurements of submicron aerosols at the California-Mexico border during the Cal-Mex 2010 field campaign ATMOSPHERIC ENVIRONMENT Levy, M. E., Zhang, R., Zheng, J., Tan, H., Wang, Y., Molina, L. T., Takahama, S., Russell, L. M., Li, G. 2014; 88: 308-319
  • Asian pollution climatically modulates mid-latitude cyclones following hierarchical modelling and observational analysis NATURE COMMUNICATIONS Wang, Y., Zhang, R., Saravanan, R. 2014; 5: 3098


    Increasing levels of anthropogenic aerosols in Asia have raised considerable concern regarding its potential impact on the global atmosphere, but the magnitude of the associated climate forcing remains to be quantified. Here, using a novel hierarchical modelling approach and observational analysis, we demonstrate modulated mid-latitude cyclones by Asian pollution over the past three decades. Regional and seasonal simulations using a cloud-resolving model show that Asian pollution invigorates winter cyclones over the northwest Pacific, increasing precipitation by 7% and net cloud radiative forcing by 1.0 W m(-2) at the top of the atmosphere and by 1.7 W m(-2) at the Earth's surface. A global climate model incorporating the diabatic heating anomalies from Asian pollution produces a 9% enhanced transient eddy meridional heat flux and reconciles a decadal variation of mid-latitude cyclones derived from the Reanalysis data. Our results unambiguously reveal a large impact of the Asian pollutant outflows on the global general circulation and climate.

    View details for DOI 10.1038/ncomms4098

    View details for Web of Science ID 000331084400007

    View details for PubMedID 24448316

  • New Directions: Light absorbing aerosols and their atmospheric impacts ATMOSPHERIC ENVIRONMENT Wang, Y., Khalizov, A., Levy, M., Zhang, R. 2013; 81: 713-715
  • Measurements of submicron aerosols in Houston, Texas during the 2009 SHARP field campaign JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Levy, M. E., Zhang, R., Khalizov, A. F., Zheng, J., Collins, D. R., Glen, C. R., Wang, Y., Yu, X., Luke, W., Jayne, J. T., Olaguer, E. 2013; 118 (18): 10518-10534

    View details for DOI 10.1002/jgrd.50785

    View details for Web of Science ID 000326025200008

  • Improving bulk microphysics parameterizations in simulations of aerosol effects JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Wang, Y., Fan, J., Zhang, R., Leung, L., Franklin, C. 2013; 118 (11): 5361-5379

    View details for DOI 10.1002/jgrd.50432

    View details for Web of Science ID 000325212600024

  • Aerosol impacts on clouds and precipitation in eastern China: Results from bin and bulk microphysics JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Fan, J., Leung, L., Li, Z., Morrison, H., Chen, H., Zhou, Y., Qian, Y., Wang, Y. 2012; 117
  • Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China ATMOSPHERIC CHEMISTRY AND PHYSICS Wang, Y., Wan, Q., Meng, W., Liao, F., Tan, H., Zhang, R. 2011; 11 (23): 12421-12436
  • Impacts of aerosols on the development and precipitation of a mesoscale squall line JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Li, G., Wang, Y., Lee, K., Diao, Y., Zhang, R. 2009; 114
  • Implementation of a two-moment bulk microphysics scheme to the WRF model to investigate aerosol-cloud interaction JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Li, G., Wang, Y., Zhang, R. 2008; 113 (D15)
  • Increased winter precipitation over the North Pacific from 1984-1994 to 1995-2005 inferred from the Global Precipitation Climatology Project GEOPHYSICAL RESEARCH LETTERS Li, G., Wang, Y., Lee, K., Diao, Y., Zhang, R. 2008; 35 (13)