This paper presents how environmental chamber data of secondary organic aerosol (SOA) formation can be interpreted using kinetic modeling techniques. Utilizing pure and mixed precursor experiments, we show that SOA formation and evaporation can be understood by explicitly treating gas-phase chemistry, gas–particle partitioning, and, notably, particle-phase oligomerization, but some of the non-linear, non-equilibrium effects must be accredited to diffusion limitations in the particle phase.
Light-absorbing carbonaceous (LAC) aerosol is an important influencing factor for global climate forcing. In this study, we used a receptor model coupling multi-wavelength absorption with chemical species to explore the source-specific LAC optical properties at a tropical marine monsoon climate zone. The results can improve our understanding of the LAC radiative effects caused by ship emissions.
Robbie Ramsay, Chiara F. Di Marco, Matthias Sörgel, Mathew R. Heal, Samara Carbone, Paulo Artaxo, Alessandro C. de Araùjo, Marta Sá, Christopher Pöhlker, Jost Lavric, Meinrat O. Andreae, and Eiko Nemitz
The Amazon rainforest is a unique laboratory to study the processes which govern the exchange of gases and aerosols to and from the atmosphere. This study investigated these processes by measuring the atmospheric concentrations of trace gases and particles at the Amazon Tall Tower Observatory. We found that the long-range transport of pollutants can affect the atmospheric composition above the Amazon rainforest and that the gases ammonia and nitrous acid can be emitted from the rainforest.
The potential temperature is routinely used in atmospheric science. We review its derivation and suggest a new potential temperature, based on a temperature-dependent parameterization of the dry air's specific heat capacity. Moreover, we compare the new potential temperature to the common one and discuss the differences which become more important at higher altitudes. Finally, we indicate some consequences of using the new potential temperature in typical applications.
During the past decade, China has devoted very substantial resources to improving the environment. These efforts have improved atmospheric particulate matter loading, but ambient ozone levels have continued to increase. In this paper we investigate the causes of the increasing ozone concentrations through analysis of a data set that is, to our knowledge, unique: a 12-year data set including ground-level O3, NOx, and VOC precursors collected at an urban site in Beijing.
Black carbon (BC) is the second strongest climate forcing pollutant in the atmosphere, after carbon dioxide. Here, we seek to understand how BC microphysical properties vary with atmospheric contexts, as these properties can influence its radiative forcing. Consistent with previous studies, we found that biomass burning BC had thicker coatings and larger core diameters than fossil fuel BC. We also present evidence to show that atmospheric aging also increases BC coating thickness.
We investigated the role of ammonia in European air quality between 1990 and 2030 under varying land and ship emissions. If ship emissions will be regulated more strictly in the future, particulate nitrate will decrease in coastal areas in northern Europe, while sulfate aerosol will decrease in the Mediterranean region. We predict a shift in the sensitivity of aerosol formation from NH3 towards NOx emissions between 1990 and 2030 in most of Europe except the eastern part of the model domain.
Particles arising from human activity interact with clouds and affect how much of the Sun's energy is reflected away. Lack of understanding about how to represent this in models leads to large uncertainties in climate predictions. We quantify cloud responses to particles in the latest UK Met Office climate model over the North Atlantic Ocean, showing that, in contrast to suggestions elsewhere, increases in cloud coverage and thickness are important over large areas.
Motor vehicle road traffic in Budapest was reduced by approximately 50% of its ordinary level due to COVID-19. In parallel, concentrations of most criteria air pollutants declined by 30–60%. Change rates of NO and NO2 with relative change in traffic intensity were the largest, total particle number concentration showed considerable dependency, while particulate matter mass concentrations did not appear to be related to urban traffic. Concentrations of O3 showed an increasing tendency.
Efforts to prevent the COVID-19 virus spreading across the globe have included travel restrictions and the closure of workplaces, leading to a significant drop in emissions of primary air pollutants. This provides for a unique opportunity to examine how air pollutant concentrations respond to an abrupt and prolonged reduction. We examine how NO2 and O3 have been affected at several urban measurement sites in the UK. We look at the change in NO2 compared to previous years and the effect on O3.
Yiqun Han, Wu Chen, Lia Chatzidiakou, Anika Krause, Li Yan, Hanbin Zhang, Queenie Chan, Ben Barratt, Rod Jones, Jing Liu, Yangfeng Wu, Meiping Zhao, Junfeng Zhang, Frank J. Kelly, Tong Zhu, and the AIRLESS team
Panel studies might be the most suitable way to link intensive air monitoring campaigns for a wide range of pollutant species and personal exposure in different micro-environments, together with epidemiological studies of detailed biological changes in humans. Panel studies are intensive, but related papers are very limited. With the successful collection of a rich dataset, we believe AIRLESS sets a good example for the design of a multidisciplinary study.
We analyzed a haze front event involving warm–dry downslope flow in December 2015 in Beijing, China. The haze front was formed by the collision between a clean warm–dry air mass flowing from a nearby mountainous region and a polluted cold–wet air mass over an urban area. We found that the polluted air advanced toward the clean air, resulting in a severe air pollution event. Our study highlights the need to further investigate the warm–dry downslope and its impacts on air pollution.
The chemical composition of aerosol particles is very important as it determines to which extent they can affect the Earth's climate by acting with solar light and modifying the properties of clouds. The South Atlantic region is a remote and under-explored region to date where these effects could be important. The measurements presented in this paper consist in the analysis of samples collected at a coastal site in Namibia. The first long-term source apportionment is presented and discussed.
Huan Song, Xiaorui Chen, Keding Lu, Qi Zou, Zhaofeng Tan, Hendrik Fuchs, Alfred Wiedensohler, Daniel R. Moon, Dwayne E. Heard, María-Teresa Baeza-Romero, Mei Zheng, Andreas Wahner, Astrid Kiendler-Scharr, and Yuanhang Zhang
Accurate calculation of the HO2 uptake coefficient is one of the key parameters to quantify the co-reduction of both aerosol and ozone pollution. We modelled various lab measurements of γHO2 based on a gas-liquid phase kinetic model and developed a state-of-the-art parameterized equation. Based on a dataset from a comprehensive field campaign in the North China Plain, we proposed that the determination of the heterogeneous uptake process for HO2 should be included in future field campaigns.
During strong synoptic control, which dominates the weather on 80 % of the days in the 2-month HyMeX-SOP1 period, the domain-integrated precipitation predictability assessed with the normalized ensemble standard deviation is above average, the wet bias is smaller and the forecast quality is generally better. In contrast, the spatial forecast quality of the most intense precipitation in the afternoon, as quantified with its 95th percentile, is superior during weakly forced synoptic regimes.
Atmospheric new particle formation and cluster growth to aerosol particles is an important field of research, in particular due to the climate change phenomenon. Evaporation rates are very difficult to account for but they are important to explain the formation and growth of particles. Different quantum chemistry (QC) methods produce substantially different values for the evaporation rates. We propose a novel approach for inferring evaporation rates of clusters from available measurements.
Connor Stahl, Melliza Templonuevo Cruz, Paola Angela Bañaga, Grace Betito, Rachel A. Braun, Mojtaba Azadi Aghdam, Maria Obiminda Cambaliza, Genevieve Rose Lorenzo, Alexander B. MacDonald, Miguel Ricardo A. Hilario, Preciosa Corazon Pabroa, John Robin Yee, James Bernard Simpas, and Armin Sorooshian
Long-term (16-month) high-frequency (weekly) measurements of size-resolved aerosol composition are reported. Important insights are discussed about factors (e.g., transport, fires, precipitation, photo-oxidation) impacting the mass size distributions of organic and sulfonic acids at a coastal megacity with diverse meteorology. The size-resolved nature of the data yielded one such finding that organic acids preferentially adsorb to dust rather than sea salt particles.
Xin Yang, Anne-M. Blechschmidt, Kristof Bognar, Audra McClure-Begley, Sara Morris, Irina Petropavlovskikh, Andreas Richter, Henrik Skov, Kimberly Strong, David W. Tarasick, Taneil Uttal, Mika Vestenius, and Xiaoyi Zhao
This is a modelling-based study on Arctic surface ozone, with a particular focus on spring ozone depletion events (i.e. with concentrations < 10 ppbv). Model experiments show that model runs with blowing-snow-sourced sea salt aerosols implemented as a source of reactive bromine can reproduce well large-scale ozone depletion events observed in the Arctic. This study supplies modelling evidence of the proposed mechanism of reactive-bromine release from blowing snow on sea ice (Yang et al., 2008).
CO is one of the major air pollutants. Our study showed that the long-term CO levels at a background station in one of the most developed areas of China decreased significantly and verified that this downward trend was attributed to the decrease in anthropogenic emissions, which indicated that the adopted pollution control policies were effective. Also, this decrease has an implication for the atmospheric chemistry considering the negative correlation between CO levels and OH radical's lifetime.
Jann Schrod, Erik S. Thomson, Daniel Weber, Jens Kossmann, Christopher Pöhlker, Jorge Saturno, Florian Ditas, Paulo Artaxo, Valérie Clouard, Jean-Marie Saurel, Martin Ebert, Joachim Curtius, and Heinz G. Bingemer
Long-term ice-nucleating particle (INP) data are presented from four semi-pristine sites located in the Amazon, the Caribbean, Germany and the Arctic. Average INP concentrations did not differ by orders of magnitude between the sites. For all sites short-term variability dominated the time series, which lacked clear trends and seasonalities. Common drivers to explain the INP levels and their variations could not be identified, illustrating the complex nature of heterogeneous ice nucleation.
This work describes new measurements of aerosol (particles) composition over the North Atlantic Ocean. It provides concentrations of polysaccharide material likely made from organisms in the surface ocean and improves our understanding of the relative importance of such fresh biogenic material compared to more recalcitrant organic carbon in forming marine organic aerosol. We aim ultimately to understand the role that ocean biology plays in cloud formation in marine regions.
Kine Onsum Moseid, Michael Schulz, Trude Storelvmo, Ingeborg Rian Julsrud, Dirk Olivié, Pierre Nabat, Martin Wild, Jason N. S. Cole, Toshihiko Takemura, Naga Oshima, Susanne E. Bauer, and Guillaume Gastineau
In this study we compare solar radiation at the surface from observations and Earth system models from 1961 to 2014. We find that the models do not reproduce the so-called global dimming as found in observations. Only model experiments with anthropogenic aerosol emissions display any dimming at all. The discrepancies between observations and models are largest in China, which we suggest is in part due to erroneous aerosol precursor emission inventories in the emission dataset used for CMIP6.
We investigated sources of carbonaceous aerosols in Beijing and Xi'an during severe winter haze. Elemental carbon (EC) was dominated by vehicle emissions in Xi’an and coal burning in Beijing. Organic carbon (OC) increment during haze days was driven by the increase in primary and secondary OC (SOC). SOC was more from fossil sources in Beijing than Xi’an, especially during haze days. In Xi’an, no strong day–night differences in EC or OC sources suggest a large accumulation of particles.
This article is about improving the modeling of agricultural ammonia emissions. By considering land use, meteorology and agricultural practices, ammonia emission totals officially reported by countries are distributed in space and time. We illustrated the first step for a better understanding of the variability of ammonia emission, with the possibility of being applied at a European scale, which is of great significance for ammonia budget research and future policy-making.
Both natural (dust, sea salt) and anthropogenic (sulfate, organic and black carbon) aerosols are common over the Red Sea coastal plains. King Abdullah University of Science and Technology (KAUST), located on the eastern coast of the Red Sea, hosts the only operating lidar system in the Arabian Peninsula, which measures atmospheric aerosols day and night. We use these lidar data and high-resolution WRF-Chem model simulations to study the potential effect of dust aerosols on Red Sea environment.
Mercury (Hg) emissions from natural resources have a large uncertainty, which is mainly derived from the forest. A long-term and multiplot (10) study of soil–air fluxes at subtropical and temperate forests was conducted. Forest soils are an important atmospheric Hg source, especially for subtropical forests. The compensation points imply that the atmospheric Hg concentration plays a critical role in inhibiting Hg emissions from the forest floor. Climate change can enhance soil Hg emissions.
Emission factors for PM10 and polycyclic aromatic hydrocarbons (PAHs) are reported for the first time ever for the indoor combustion of 12 common types of municipal solid waste that are frequently burned in households worldwide. We have found that waste burning emits up to 40 times more PM10 and 800 times more PAHs than the combustion of dry firewood. Our finding highlights the need for coordinated actions against illegal waste combustion and the extreme health hazard associated with it.