Aerosol acidity plays a key role in secondary aerosol formation. To provide a more comprehensive reference for aerosol pH and a basis for controlling secondary aerosol generation, this study used the latest data covering four seasons and different particle sizes to obtain the characteristics of aerosol pH and explore the main factors affecting aerosol pH and gas–particle partitioning in the Beijing area.

Aircraft measurements are used to study aerosol–cloud interaction, with a focus on three understudied topics (separation of aerosol effects from dynamic effects, dispersion effects, and entrainment-mixing processes). After constraining cloud dynamics, positive correlation between relative dispersion and CCN concentration became stronger, implying that perturbations of dynamics could underestimate dispersion effect. Entrainment mixing is predominantly extremely inhomogeneous in the stratocumulus.

This study investigates the impacts of urban and fire emissions on the concentration, composition, and optical properties of submicron particulate matter (PM₁) in central Amazonia during the dry season. Biomass-burning and urban emissions appeared to contribute at least 80 % of brown carbon absorption while accounting for 30 % to 40 % of the organic PM₁ mass concentration. Only a fraction of the 9-fold increase in mass concentration relative to the wet season was due to biomass burning.

We have investigated the molecular interactions between succinic acid and sulfuric acid–base clusters in the presence of hydration, including ammonia and dimethylamine. Our results indicate that the multicomponent nucleation involving organic acids, sulfuric acid, and base species promotes new particle formation in the atmosphere, particularly under polluted conditions.

Wintertime volatile organic compounds (VOCs) in suburban and urban Beijing were measured. Urban VOC concentrations were much higher than suburban ones, but the emission features were similar. The photochemical processes were more active in the urban site, resulting in the high daytime formation of oxygenated VOCs. In addition, human activities during holidays can largely influence the VOC levels. These results are helpful in better understanding the atmospheric chemistry of VOCs in Beijing.

Current understanding of OA sources is limited by the chemical resolution of existing real-time measurement technology. We describe the first wintertime deployment of a novel extractive electrospray ionization time-of-flight mass spectrometer, which provides near-molecular OA measurements with high time resolution. We show that biomass combustion strongly influences winter OA. Via factor analysis, aging-dependent signatures and time contributions of biomass-combustion-derived OA are resolved.

Effects of SO₂ and NH₃ on SA formation from unburned gasoline vapor were investigated in a 30 m³ smog chamber. With the increase in SO₂ and NH₃ concentrations, formation of SA and each of its chemical species was promoted. Meanwhile, NPF and particle size growth were also significantly enhanced. This work indicates that gasoline evaporation emissions will be a significant source of SA and sulfur- and nitrogen-containing organics, especially in the presence of high concentrations of SO₂ and NH₃.

The interaction between radiation and clouds represents a source of uncertainty in numerical weather prediction (NWP), due to both intrinsic problems of one-dimensional radiation schemes and poor representation of clouds. The underlying question addressed in this study is how large the bias is of radiative heating rates in NWP models for shallow cumulus clouds and how it scales with various parameters, such as solar zenith angle, surface albedo, cloud cover and liquid water path.

The Greenland Ice Sheet (GrIS) is rapidly melting. Snowfall is the only source of ice mass over the GrIS. We use satellite observations to assess how much snow on average falls over the GrIS and what the annual cycle and spatial distribution of snowfall is. We find the annual mean snowfall over the GrIS inferred from CloudSat to be 34 ± 7.5 cm yr⁻¹ liquid equivalent.

Aerosols that serve as seeds for cloud ice formation are important to study because they impact cloud radiative properties, lifetime, and precipitation formation. We present an investigation of ice-nucleating particles (INPs) from aerosol, rime, and snow samples collected in clear and cloudy conditions during winter storms in the Swiss Alsp. INPs were more abundant and effective when storms originated from the south. We use spectral characteristics to investigate warm versus cold mode INPs.

Semi-volatile and intermediate-volatility organic compounds (S–IVOCs) are considered critical precursors of secondary organic aerosol (SOA), which is an important component of fine particulate matter (PM_2.5). In this study, an emission inventory of S–IVOCs in the Pearl River Delta (PRD) region was developed for the first time for the year 2010, while the contributions of S–IVOCs to SOA formation was evaluated by the WRF-Chem model.

The climate impact of air traffic is to a large degree caused by changes in cirrus cloudiness resulting from the formation of contrails. We use an atmospheric climate model with a contrail cirrus parameterization to investigate the climate impact of contrail cirrus for the year 2050. The strong increase in contrail cirrus radiative forcing due to the projected increase in air traffic volume cannot be compensated for by the reduction of soot emissions and by improvements in propulsion efficiency.

During production and use of carbon nanomaterials, they are prone to enter the environment and ultimately the human body, and subsequently to pose a risk of adverse health effects. This work has for the first time found that epoxide is highly active to form ROS, possibly leading to a strong oxidation stress to humans, while carboxylation and hydroxylation have little influence on the oxidation potential. This suggests that more attention should be paid to epoxide-containing carbon nanomaterials.

Air pollution is one of the most pressing environmental issues in the Kathmandu Valley, the capital city of Nepal. We estimated emissions from two of the major source types in the valley (vehicles and brick kilns) and found that they have significant impacts on air quality surrounding the valley. Our results highlight the importance of improving local emissions estimates for air quality modeling.

We show substantial improvements in the near-surface BC mass concentrations simulated by a regional chemistry transport model, WRF-Chem, over the Indian region, upon scaling up the CMIP5 equivalent anthropogenic BC emissions by 3 and introducing a diurnal variation to those. The diurnality in emissions alone significantly controls the simulated near-surface BC mass concentration, with a mean delay of 3–4 h. The simulated AOD, however, is still underestimated.

The systematic validation and comparison of MAIAC, DT, and DB AOD products across China from 2000 to 2017 is presented. In this process, the overall accuracy, land type dependence, view geometry dependence, spatiotemporal retrieval accuracy, spatial variation pattern, and spatiotemporal completeness of the three products are analyzed in detail. In general, MAIAC achieves higher accuracy than DT and DB, but DT and DB may perform better than MAIAC under some specific land cover types or seasons.

This study presents a full description and evaluation of a global–regional nested aerosol and atmospheric chemistry model (IAP-AACM). The simulation for 2014 is evaluated against model datasets and a range of observational datasets. The results show that IAP-AACM is within the range of other models, and reproduces both spatial and seasonal variation of trace gases and aerosols over most areas well. In future, we recommend improving the model's ability to capture high spatial variation of PM_2.5.

In this research, we combine satellite measurements of ozone with a chemical transport model of the atmosphere. The focus is on the ozone concentration between the surface and 6 km above mean sea level, since in that altitude range ozone has the highest impact on living organisms. Monthly mean ozone fields show significant improvements and more detail, especially for features such as biomass-burning-enhanced ozone concentrations and outflow of ozone-rich air from Asia over the Pacific.

We present a study based on GLORIA aircraft and MLS/ACE-FTS/CALIOP satellite measurements during the Arctic winter 2015/16, which demonstrate (for the Arctic) unusual chlorine deactivation into HCl instead of ClONO₂ due to low ozone abundances in the lowermost stratosphere, with a focus at 380 K potential temperature. The atmospheric models CLaMS and EMAC are evaluated, and measured ClONO₂ is linked with transport and in situ deactivation in the lowermost stratosphere.

Severe and deteriorating surface ozone pollution over major Chinese cities has become an emerging environmental concern in China. This study assesses the source contributions (including anthropogenic, background, and individual natural sources) and meteorological influences of surface ozone over China in 2016–2017 using the GEOS-Chem chemical transport model at high horizontal resolution with the most up-to-date Chinese anthropogenic emission inventory.