scholarly journals Size-dependent influence of NOx on the growth rates of organic aerosol particles

2020 ◽  
Vol 6 (22) ◽  
pp. eaay4945 ◽  
Author(s):  
C. Yan ◽  
W. Nie ◽  
A. L. Vogel ◽  
L. Dada ◽  
K. Lehtipalo ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Underlying Mechanism ◽  
Early Growth ◽  
Climatic Effects ◽  
Size Dependent ◽  
Forest Regions

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

scholarly journals Molecular understanding of the suppression of new-particle formation by isoprene

2020 ◽  
Author(s):  
Martin Heinritzi ◽  
Lubna Dada ◽  
Mario Simon ◽  
Dominik Stolzenburg ◽  
Andrea C. Wagner ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Early Growth ◽  
Chemical System ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Ambient Conditions

Abstract. Nucleation of atmospheric vapors produces more than half of global cloud condensation nuclei and so has an important influence on climate. Recent studies show that monoterpene (C10H16) oxidation yields highly-oxygenated products that can nucleate with or without sulfuric acid. Monoterpenes are emitted mainly by trees, frequently together with isoprene (C5H8), which has the highest global emission of all organic vapors. Previous studies have shown that isoprene suppresses new-particle formation from monoterpenes, but the cause of this suppression is under debate. Here, in experiments performed under atmospheric conditions in the CERN CLOUD chamber, we show that isoprene reduces the yield of highly-oxygenated dimers with 19 or 20 carbon atoms – which drive particle nucleation and early growth – while increasing the production of dimers with 14 or 15 carbon atoms. The dimers (termed C20 and C15, respectively) are produced by termination reactions between pairs of peroxy radicals (RO2·) arising from monoterpenes or isoprene. Compared with pure monoterpene conditions, isoprene reduces nucleation rates at 1.7 nm (depending on the isoprene/monoterpene ratio) and approximately halves particle growth rates between 1.3 and 3.2 nm. However, above 3.2 nm, C15 dimers contribute to secondary organic aerosol and the growth rates are unaffected by isoprene. We further show that increased hydroxyl radical (OH·) reduces particle formation in our chemical system rather than enhances it as previously proposed, since it increases isoprene derived RO2· radicals that reduce C20 formation. RO2· termination emerges as the critical step that determines the HOM distribution and the corresponding nucleation capability. Species that reduce the C20 yield, such as NO, HO2 and as we show isoprene, can thus effectively reduce biogenic nucleation and early growth. Therefore the formation rate of organic aerosol in a particular region of the atmosphere under study will vary according to the precise ambient conditions.

scholarly journals New particle growth and shrinkage observed in subtropical environments

2012 ◽  
Vol 12 (7) ◽  
pp. 18605-18650
Author(s):  
L.-H. Young ◽  
S.-H. Lee ◽  
V. Kanawade ◽  
T.-C. Hsiao ◽  
Y. L. Lee ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Inversion Layer ◽  
Type A ◽  
Particle Growth ◽  
Traffic Emissions ◽  
Contour Plot ◽  
Volatile Species ◽  
New Particles

Abstract. We present the first systematic analysis for new particle formation (NPF), growth and shrinkage of new particles observed at four different sites in subtropical Central Taiwan. A total of 14 NPF events were identified during 137 days of ambient measurements during a cold and warm season. The derived nucleation rates of 1 nm particles (J1) and growth rates were in the range of 39.6–252.9 cm−3 s−1 and 6.5–14.5 nm h−1, respectively. The NPF events occurred on days either with low condensation sink (CS), increased morning traffic emissions and the breakup of nocturnal inversion layer (type A), or with high CS, minimum levels of primary traffic emissions and enhanced atmospheric dilution (type B). On non-event days, the particle number concentrations were mostly driven by traffic emissions. We have also observed shrinkage of new particles (type A-S and B-S), reversal of growth, during five out of the 14 NPF events. In intense shrinkage cases, the grown particles shrank back to the smallest measurable size of ~10 nm, thereby creating a unique "arch-like" shape in the size distribution contour plot. The particle shrinkage rates ranged from 5.1 to 7.6 nm h−1. The ratios of shrinkage-to-growth rates were mostly in the range of 0.40–0.65, suggesting that a large fraction of the condensable species that contributed to growth were likely semi-volatile. The particle shrinkage was related to air masses with low CS due to atmospheric dilution, high ambient temperature and low relative humidity and such atmospheric conditions may have facilitated the evaporation of semi-volatile species from the particles to the gas phase. Our observations show that the new particle growth may be a~reversible process and the evaporating semi-volatile species are important for the growth of new particles to cloud condensation nuclei sizes.

scholarly journals Molecular understanding of the suppression of new-particle formation by isoprene

2020 ◽  
Vol 20 (20) ◽  
pp. 11809-11821 ◽  
Author(s):  
Martin Heinritzi ◽  
Lubna Dada ◽  
Mario Simon ◽  
Dominik Stolzenburg ◽  
Andrea C. Wagner ◽  
...  
Keyword(s):  
Growth Rates ◽  
Cloud Condensation Nuclei ◽  
Formation Rate ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Early Growth ◽  
Chemical System ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Ambient Conditions

Abstract. Nucleation of atmospheric vapours produces more than half of global cloud condensation nuclei and so has an important influence on climate. Recent studies show that monoterpene (C10H16) oxidation yields highly oxygenated products that can nucleate with or without sulfuric acid. Monoterpenes are emitted mainly by trees, frequently together with isoprene (C5H8), which has the highest global emission of all organic vapours. Previous studies have shown that isoprene suppresses new-particle formation from monoterpenes, but the cause of this suppression is under debate. Here, in experiments performed under atmospheric conditions in the CERN CLOUD chamber, we show that isoprene reduces the yield of highly oxygenated dimers with 19 or 20 carbon atoms – which drive particle nucleation and early growth – while increasing the production of dimers with 14 or 15 carbon atoms. The dimers (termed C20 and C15, respectively) are produced by termination reactions between pairs of peroxy radicals (RO2⚫) arising from monoterpenes or isoprene. Compared with pure monoterpene conditions, isoprene reduces nucleation rates at 1.7 nm (depending on the isoprene ∕ monoterpene ratio) and approximately halves particle growth rates between 1.3 and 3.2 nm. However, above 3.2 nm, C15 dimers contribute to secondary organic aerosol, and the growth rates are unaffected by isoprene. We further show that increased hydroxyl radical (OH⚫) reduces particle formation in our chemical system rather than enhances it as previously proposed, since it increases isoprene-derived RO2⚫ radicals that reduce C20 formation. RO2⚫ termination emerges as the critical step that determines the highly oxygenated organic molecule (HOM) distribution and the corresponding nucleation capability. Species that reduce the C20 yield, such as NO, HO2 and as we show isoprene, can thus effectively reduce biogenic nucleation and early growth. Therefore the formation rate of organic aerosol in a particular region of the atmosphere under study will vary according to the precise ambient conditions.

scholarly journals A secondary organic aerosol formation model considering successive oxidation aging and kinetic condensation of organic compounds: global scale implications

2011 ◽  
Vol 11 (3) ◽  
pp. 1083-1099 ◽  
Author(s):  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Lower Boundary ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Forest Site ◽  
Aerosol Formation ◽  
Formation Model ◽  
Condensation Nuclei

Abstract. The widely used two-product secondary organic aerosol (SOA) formation model has been extended in this study to consider the volatility changes of secondary organic gases (SOG) arising from the aging process as well as the kinetic condensation of low volatile SOG (LV-SOG). In addition to semi-volatile SOG (SV-SOG) with saturation vapor pressure at 290 K (C*290) in the range of ~3 ppt–3 ppb and medium-volatile SOG (MV-SOG) with C*290 in the range of ~0.3–300 ppb, we add a third component representing LV-SOG with C*290 below ~3 ppt and design a scheme to transfer MV-SOG to SV-SOG and SV-SOG to LV-SOG associated with oxidation aging. This extended SOA formation model has been implemented in a global aerosol model (GEOS-Chem) and the co-condensation of H2SO4 and LV-SOG on pre-existing particles is explicitly simulated. We show that, over many parts of the continents, LV-SOG concentrations are generally a factor of ~2–20 higher than those of H2SO4 and the kinetic condensation of LV-SOG significantly enhances particle growth rates. Comparisons of the simulated and observed evolution of particle size distributions at a boreal forest site (Hyytiälä, Finland) clearly show that LV-SOG condensation is critical in order to bring the simulations closer to the observations. With the new SOA formation scheme, annual mean SOA mass increases by a factor of 2–10 in many parts of the boundary layer and reaches above 0.5 μg m−3 in most parts of the main continents, improving the agreement with aerosol mass spectrometer (AMS) SOA measurements. While the new scheme generally decreases the concentration of condensation nuclei larger than 10 nm by 3–30% in the lower boundary layer as a result of enhanced surface area and reduced nucleation rates, it substantially increases the concentration of cloud condensation nuclei at a water supersaturation ratio of 0.2%, ranging from ~5–20% over a large fraction of oceans and high latitude continents to more than 50% over some parts of South America, Australia, and Indonesia. Our study highlights the importance for global aerosol models to explicitly account for the oxidation aging of SOGs and their contribution to particle growth.

scholarly journals The role of ions in new particle formation in the CLOUD chamber

2017 ◽  
Vol 17 (24) ◽  
pp. 15181-15197 ◽  
Author(s):  
Robert Wagner ◽  
Chao Yan ◽  
Katrianne Lehtipalo ◽  
Jonathan Duplissy ◽  
Tuomo Nieminen ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Particle Growth ◽  
Particle Formation ◽  
Chemical Compositions ◽  
New Particle Formation ◽  
Ion Concentrations ◽  
Ion Filter ◽  
Charged Clusters ◽  
A Charge

Abstract. The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nanoparticle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e., in conditions in which neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.5 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion–ion recombination before they grew to 2.5 nm. At this size, more than 90 % of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.5 nm. Observations at Hyytiälä, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.

scholarly journals An extended secondary organic aerosol formation model: effect of oxidation aging and implications

2010 ◽  
Vol 10 (8) ◽  
pp. 19811-19844 ◽  
Author(s):  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Lower Boundary ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Forest Site ◽  
Aerosol Formation ◽  
Formation Model ◽  
Condensation Nuclei

Abstract. The widely used 2-product secondary organic aerosol (SOA) formation model has been extended in this study to consider the volatility changes of secondary organic gases (SOGs) arising from the aging process. In addition to semi-volatile SOG (SV-SOG) and medium-volatile SOG (MV-SOG), we add a third component representing low-volatile SOG (LV-SOG) and design a scheme to transfer MV-SOG to SV-SOG and SV-SOG to LV-SOG associated with oxidation aging. This extended SOA formation model has been implemented in a global aerosol model (GEOS-Chem) and the co-condensation of H2SO4 and LV-SOG on pre-existing particles is explicitly simulated. We show that, over many parts of the continents, LV-SOG concentrations are generally a factor of ~2–20 higher than those of H2SO4 and LV-SOG condensation significantly enhances particle growth rates. Comparisons of the simulated and observed evolution of particle size distributions in a boreal forest site (Hyytiälä, Finland) clearly show that LV-SOG condensation is critical in order to bring the simulations closer to the observations. With the new SOA formation scheme, annual mean SOA mass increases by a fact of 2–10 in many parts of the boundary layer and reaches above 1 μg m−3 in most parts of the main continents. As a result of enhanced surface area and reduced nucleation rates, the new scheme generally decreases the concentration of condensation nuclei larger than 10 nm (CN10) by 3–30% in the lower boundary layer, which slightly improves agreement between simulated annual mean CN10 values and those observed in 21 surface sites around the globe. SOG oxidation aging and LV-SOG condensation substantially increases the concentration of cloud condensation nuclei at a water supersaturation ratio of 0.2%, ranging from ~3–10% over a large fraction of oceans to ~10–100% over major continents. Our study highlights the importance for global aerosol models to explicitly account for the oxidation aging of SOGs and their contribution of particle growth.

scholarly journals The role of ions in new-particle formation in the CLOUD chamber

2017 ◽  
Author(s):  
Robert Wagner ◽  
Chao Yan ◽  
Katrianne Lehtipalo ◽  
Jonathan Duplissy ◽  
Tuomo Nieminen ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Particle Growth ◽  
Particle Formation ◽  
Chemical Compositions ◽  
New Particle Formation ◽  
Ion Concentrations ◽  
Ion Filter ◽  
Charged Clusters ◽  
A Charge

Abstract. The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nano-particle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e. in conditions where neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.2 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion–ion recombination before they grew to 2.2 nm. At this size, more than 90 % of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.2 nm. Observations at Hyytiälä, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.

scholarly journals Efficiency of cloud condensation nuclei formation from ultrafine particles

2006 ◽  
Vol 6 (6) ◽  
pp. 10991-11023 ◽  
Author(s):  
J. R. Pierce ◽  
P. J. Adams
Keyword(s):  
Size Distribution ◽  
Ultrafine Particles ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Ultrafine Particle ◽  
Particle Growth ◽  
Aerosol Size Distribution ◽  
Condensation Nuclei ◽  
Anthropogenic Aerosols ◽  
Different Parts

Abstract. Atmospheric cloud condensation nuclei (CCN) concentrations are a key uncertainty in the assessment of the effect of anthropogenic aerosols on clouds and climate. The ability of new ultrafine particles to grow to become CCN varies throughout the atmosphere and must be understood in order to understand CCN formation. We have developed the Probability of Ultrafine particle Growth (PUG) model to answer questions regarding which growth and sink mechanisms control this growth, how the growth varies between different parts of the atmosphere and how uncertainties with respect to the magnitude and size distribution of ultrafine emissions translates into uncertainty in CCN generation. It was found in most cases that condensation is the dominant growth mechanism and coagulation with larger particles is the dominant sink mechanism for ultrafine particles. In this work we found that the probability of a new ultrafine particle generating a CCN varies from <0.1% to >90% in different parts of the atmosphere, though in the boundary layer a large fraction of ultrafine particles have a probability between 5% and 40%. Some regions, such as the tropical free troposphere, are areas with high probabilities; however, variability within regions makes it difficult to predict which regions of the atmosphere are most efficient for generating CCN from ultrafine particles. For a given mass of primary ultrafine aerosol, an uncertainty of a factor of two in the modal diameter can lead to an uncertainty in the number of CCN generated as high as a factor for eight. It was found that no single moment of the primary aerosol size distribution, such as total mass or number, is a robust predictor of the number of CCN ultimately generated. Therefore, a complete description of the size distribution is generally required for global aerosol microphysics models.

Single-particle measurements of phase partitioning between primary and secondary organic aerosols

2016 ◽  
Vol 189 ◽  
pp. 31-49 ◽  
Author(s):  
Ellis Shipley Robinson ◽  
Neil M. Donahue ◽  
Adam T. Ahern ◽  
Qing Ye ◽  
Eric Lipsky
Keyword(s):  
Single Particle ◽  
Organic Molecules ◽  
Secondary Organic Aerosols ◽  
Large Fraction ◽  
Organic Aerosols ◽  
Organic Aerosol ◽  
Urban Atmosphere ◽  
Aerosol Formation ◽  
Phase Partitioning ◽  
Single Particle Mass Spectrometry

Organic aerosols provide a measure of complexity in the urban atmosphere. This is because the aerosols start as an external mixture, with many populations from varied local sources, that all interact with each other, with background aerosols, and with condensing vapors from secondary organic aerosol formation. The externally mixed particle populations start to evolve immediately after emission because the organic molecules constituting the particles also form thermodynamic mixtures – solutions – in which a large fraction of the constituents are semi-volatile. The external mixtures are thus well out of thermodynamic equilibrium, with very different activities for many constituents, and yet also have the capacity to relax toward equilibrium via gas-phase exchange of semi-volatile vapors. Here we describe experiments employing quantitative single-particle mass spectrometry designed to explore the extent to which various primary organic aerosol particle populations can interact with each other or with secondary organic aerosols representative of background aerosol populations. These methods allow us to determine when these populations will and when they will not mix with each other, and then to constrain the timescales for that mixing.

scholarly journals Size-resolved characterization of organic aerosol in the North China Plain: new insights from high resolution spectral analysis

2021 ◽  
Author(s):  
Weiqi Xu ◽  
Chun Chen ◽  
Yanmei Qiu ◽  
Conghui Xie ◽  
Yunle Chen ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
North China Plain ◽  
North China ◽  
Fine Particles ◽  
Large Fraction ◽  
Organic Aerosol ◽  
Size Distributions ◽  
The North ◽  
The Impact

Organic aerosol (OA), a large fraction of fine particles, has a large impact on climate radiative forcing and human health, and the impact depends strongly on size distributions. Here we...

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