Studying new particle formation from chemical emissions from sea surface using  ship-borne air-sea-interaction tanks

2021 ◽  
Author(s):  
Maija Peltola ◽  
Manon Rocco ◽  
Neill Barr ◽  
Erin Dunne ◽  
James Harnwell ◽  
...  
Keyword(s):  
Marine Biology ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Chemical Species ◽  
Particle Formation ◽  
Biological Properties ◽  
The European Union ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Horizon 2020

<p>Even though oceans cover over 70% of the Earth’s surface, the ways in which oceans interact with climate are not fully known. Marine micro-organisms such as phytoplankton can play an important role in regulating climate by releasing different chemical species into air. In air these chemical species can react and form new aerosol particles. If grown to large enough sizes, aerosols can influence climate by acting as cloud condensation nuclei which influence the formation and properties of clouds. Even though a connection of marine biology and climate through aerosol formation was first proposed already over 30 years ago, the processes related to this connection are still uncertain.</p><p>To unravel how seawater properties affect aerosol formation and to identify which chemical species are responsible for aerosol formation, we built two Air-Sea-Interaction Tanks (ASIT) that isolate 1000 l of seawater and 1000 l of air directly above the water. The used seawater was collected from different locations during a ship campaign on board the R/V Tangaroa in the South West Pacific Ocean, close to Chatham Rise, east of New Zealand. Seawater from one location was kept in the tanks for 2-3 days and then changed. By using seawater collected from different locations, we could obtain water with different biological populations. To monitor the seawater, we took daily samples to determine its chemical and biological properties.</p><p>The air in the tanks was continuously flushed with particle filtered air. This way the air had on average 40 min to interact with the seawater surface before being sampled. Our air sampling was continuous and consisted of aerosol and air chemistry measurements. The instrumentation included measurements of aerosol number concentration from 1 to 500 nm and  chemical species ranging from ozone and sulphur dioxide to volatile organic compounds and chemical composition of molecular clusters.</p><p>Joining the seawater and atmospheric data together can give us an idea of what chemical species are emitted from the water into the atmosphere and whether these species can form new aerosol particles. Our preliminary results show a small number of particles in the freshly nucleated size range of 1-3 nm in the ASIT headspaces, indicating that new aerosol particles can form in the ASIT headspaces. In this presentation, we will also explore which chemical species could be responsible for aerosol formation and which plankton groups could be related to the emissions of these species. Combining these results with ambient data and modelling work can shed light on how important new particle formation from marine sources is for climate.</p><p>Acknowledgements: Sea2Cloud project is funded by European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 771369).</p>

scholarly journals Ion-induced sulfuric acid–ammonia nucleation drives particle formation in coastal Antarctica

2018 ◽  
Vol 4 (11) ◽  
pp. eaat9744 ◽  
Author(s):  
T. Jokinen ◽  
M. Sipilä ◽  
J. Kontkanen ◽  
V. Vakkari ◽  
P. Tisler ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Growth ◽  
Field Studies ◽  
Particle Formation ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Radiative Balance ◽  
Secondary Aerosol

Formation of new aerosol particles from trace gases is a major source of cloud condensation nuclei (CCN) in the global atmosphere, with potentially large effects on cloud optical properties and Earth’s radiative balance. Controlled laboratory experiments have resolved, in detail, the different nucleation pathways likely responsible for atmospheric new particle formation, yet very little is known from field studies about the molecular steps and compounds involved in different regions of the atmosphere. The scarcity of primary particle sources makes secondary aerosol formation particularly important in the Antarctic atmosphere. Here, we report on the observation of ion-induced nucleation of sulfuric acid and ammonia—a process experimentally investigated by the CERN CLOUD experiment—as a major source of secondary aerosol particles over coastal Antarctica. We further show that measured high sulfuric acid concentrations, exceeding 107 molecules cm−3, are sufficient to explain the observed new particle growth rates. Our findings show that ion-induced nucleation is the dominant particle formation mechanism, implying that galactic cosmic radiation plays a key role in new particle formation in the pristine Antarctic atmosphere.

scholarly journals Formation and characteristics of ions and charged aerosol particles in a native Australian Eucalypt forest

2008 ◽  
Vol 8 (1) ◽  
pp. 129-139 ◽  
Author(s):  
T. Suni ◽  
M. Kulmala ◽  
A. Hirsikko ◽  
T. Bergman ◽  
L. Laakso ◽  
...  
Keyword(s):  
Growth Rates ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Cluster Ions ◽  
Native Forest ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Eucalypt Forest ◽  
The World ◽  
Strong Source

Abstract. Biogenic aerosol formation is likely to contribute significantly to the global aerosol load. In recent years, new-particle formation has been observed in various ecosystems around the world but hardly any measurements have taken place in the terrestrial Southern Hemisphere. Here, we report the first results of atmospheric ion and charged particle concentrations as well as of new-particle formation in a Eucalypt forest in Tumbarumba, South-East Australia, from July 2005 to October 2006. The measurements were carried out with an Air Ion Spectrometer (AIS) with a size range from 0.34 to 40 nm. The Eucalypt forest was a very strong source of new aerosol particles. Daytime aerosol formation took place on 52% of days with acceptable data, which is 2–3 times as often as in the Nordic boreal zone. Average growth rates for negative/positive 1.5–3 nm particles during these formation events were 2.89/2.68 nmh−1, respectively; for 3-7 nm particles 4.26/4.03, and for 7–20 nm particles 8.90/7.58 nmh−1, respectively. The growth rates for large ions were highest when the air was coming from the native forest which suggests that the Eucalypts were a strong source of condensable vapours. Average concentrations of cluster ions (0.34–1.8 nm) were 2400/1700 cm−3 for negative/positive ions, very high compared to most other measurements around the world. One reason behind these high concentrations could be the strong radon efflux from the soils around the Tumbarumba field site. Furthermore, comparison between night-time and daytime concentrations supported the view that cluster ions are produced close to the surface within the boundary layer also at night but that large ions are mostly produced in daytime. Finally, a previously unreported phenomenon, nocturnal aerosol formation, appeared in 32% of the analysed nights but was clustered almost entirely within six months from summer to autumn in 2006. From January to May, nocturnal formation was 2.5 times as frequent as daytime formation. Therefore, it appears that in summer and autumn, nocturnal production was the major mechanism for aerosol formation in Tumbarumba.

scholarly journals New particle formation events observed at King Sejong Station, Antarctic Peninsula – Part 1: Physical characteristics and contribution to cloud condensation nuclei

2018 ◽  
Author(s):  
Jaeseok Kim ◽  
Young Jun Yoon ◽  
Yeontae Gim ◽  
Jin Hee Choi ◽  
Hyo Jin Kang ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Physical Characteristics ◽  
Weddell Sea ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Source Rate ◽  
The Mean

Abstract. The physical characteristics of aerosol particles during a particle burst observed at King Sejong Station in Antarctic Peninsula from March 2009 to December 2016 were analyzed. This study focuses on the seasonal variation in parameters related to particle formation such as the occurrence, formation rate (FR) and growth rate (GR), condensation sink (CS), and source rate of condensable vapor. The number concentrations during new particle formation (NPF) events varied from 1707 cm−3 to 83 120 cm−3, with an average of 20 649 ± 9290 cm−3, and the duration of the NPF events ranged from 0.6 h to 14.4 h, with a mean of 4.6 ± 1.5 h. The NPF event dominantly occurred during austral summer period (~ 72 %). The mean values of FR and GR of the aerosol particles were 2.79 ± 1.05 cm−3 s−1 and 0.68 ± 0.27 nm h−1, respectively showing enhanced rates in the summer season. The mean value of FR at King Sejong Station was higher than that at other sites in Antarctica, at 0.002–0.3 cm−3 s−1, while those of growth rates was relatively similar results observed by precious studies, at 0.4~4.3 nm h−1. The average values of CS and source rate of condensable vapor were (6.04 ± 2.74) × 10−3 s−1 and (5.19 ± 3.51) × 104 cm−3 s−1, respectively. The contribution of particle formation to cloud condensation nuclei (CCN) concentration was also investigated. The CCN concentration during the NPF period increased approximately 9 % compared with the background concentration. In addition, the effects of the origin and pathway of air masses on the characteristics of aerosol particles during a NPF event were determined. The FRs were similar regardless of the origin and pathway, whereas the GRs of particles originating from the Antarctic Peninsula and the Bellingshausen Sea, at 0.77 ± 0.25 nm h−1 and 0.76 ± 0.30 nm h−1, respectively, were higher than those of particles originating from the Weddell Sea (0.41 ± 0.15 nm h−1).

scholarly journals Evaluation of the contribution of new particle formation to cloud droplet in urban atmosphere

2021 ◽  
Author(s):  
Sihui Jiang ◽  
Fang Zhang ◽  
Jingye Ren ◽  
Lu Chen ◽  
Xing Yan ◽  
...  
Keyword(s):  
Water Vapor ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
Particle Formation ◽  
Urban Atmosphere ◽  
Primary Sources ◽  
New Particle Formation ◽  
Multiple Sources ◽  
Considerable Impact

Abstract. New particle formation (NPF) is a large source of cloud condensation nuclei (CCN) and cloud droplet in the troposphere. In this study, we quantified the contribution of NPF to cloud droplet number concentration (CDNC, or Nd) at typical updraft velocities (V) in clouds using a field campaign data of aerosol number size distribution and chemical composition observed on May 25–June 18, 2017 in urban Beijing. We show that the NPF drives the variations of CCN and cloud droplet and increases Nd by 30–33 % at V = 0.3–3 m s−1 in urban atmosphere. A markedly reduction in Nd is observed due to water vapor competition with consideration of actual environmental updraft velocity, decreasing by 11.8 ± 5.0 % at V = 3 m s−1 and 19.0 ± 4.5 % at V = 0.3 m s−1 compared to that from a prescribed supersaturation. The effect of water vapor competition becomes smaller at larger V that can provide more sufficient water vapor. Essentially, water vapor competition led to the reduction in Nd by decreasing the environmental maximum supersaturation (Smax) for the activation of aerosol particles. It is shown that Smax was decreased by 14.5–11.7 % for V = 0.3–3 m s−1. Particularly, the largest suppression of cloud droplet formation due to the water vapor competition is presented at extremely high aerosol particle number concentrations. As a result, although a larger increase of CCN-size particles by NPF event is derived on clean NPF day when pre-existing background aerosol particles are very low, there is no large discrepancy in the enhancement of Nd by NPF between the clean and polluted NPF day. We finally show a considerable impact of the primary sources when evaluating the NPF contribution to cloud droplet based on a case study. Our study highlights the importance of fully consideration of both the environmental meteorological conditions and multiple sources (i.e. secondary and primary) to evaluate the NPF effect on clouds and the associated climate effects in polluted regions.

scholarly journals Large difference in aerosol radiative effects from BVOC-SOA treatment in three ESMs

2020 ◽  
Author(s):  
Moa K. Sporre ◽  
Sara M. Blichner ◽  
Roland Schrödner ◽  
Inger H. H. Karset ◽  
Terje K. Berntsen ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Particle Formation ◽  
Earth System ◽  
New Particle Formation ◽  
Aerosol Formation ◽  
Radiative Effects ◽  
Sensitivity Experiments ◽  
Aerosol Radiative Effects ◽  
The Impact ◽  
Aerosol Radiative

Abstract. Biogenic volatile organic compounds (BVOCs) emitted from vegetation are oxidized in the atmosphere and can form aerosol particles either by contributing to new particle formation or by condensing onto existing aerosol particles. As the understanding of the importance of BVOCs for aerosol formation has increased over the past 10 years these processes have made their way into Earth System Models (ESMs). In this study, sensitivity experiments are run with three different ESMs, (the Norwegian Earth System Model (NorESM), EC-Earth and ECHAM) to investigate how the direct and indirect aerosol radiative effects are affected by changes in the formation of secondary organic aerosol (SOA) from BVOCs. In the first two sensitivity model experiments, the yields of SOA precursors from oxidation of BVOCs are changed by ± 50 %. For the third sensitivity test, the formed oxidation products do not participate in the formation of new particles, but are only allowed to condense onto existing aerosols. In the last two sensitivity experiments, the emissions of BVOC compounds (isoprene and monoterpenes) are turned off, one at a time. The results show that the impact on the direct radiative effect (DRE) are linked to the changes in the SOA production in the models, where more SOA leads to a stronger DRE and vice versa. The magnitude by which the DRE changes (maximally 0.15 W m−2 globally averaged) in response to the SOA changes however varies between the models, with EC-Earth displaying the largest changes. The results for the cloud radiative effects (CRE) are more complicated than for the DRE. The changes in CRE differ more among the ESMs and for some sensitivity experiments they even have different signs. The most sensitive models are NorESM and EC-Earth, which has CRE changes of up to 0.82 W m−2. The varying responses in the different models are connected to where in the aerosol size distributions the changes in mass and number due to SOA formation occur, in combination with the aerosol number concentration levels in the models. We also find that interactive gas-phase chemistry as well as the new particle formation parameterization have important implications for the DRE and CRE in some of the sensitivity experiments. The results from this study indicate that BVOC-SOA treatment in ESMs can have a substantial impact on the modelled climate but that the sensitivity varies greatly between the models. Since BVOC emissions have changed historically and will continue to change in the future, the spread in model results found in this study introduces uncertainty into ESM estimates of aerosol forcing from land-use change and BVOC feedback strengths.

scholarly journals New particle formation events observed at King Sejong Station, Antarctic Peninsula – Part 1: Physical characteristics and contribution to cloud condensation nuclei

2019 ◽  
Vol 19 (11) ◽  
pp. 7583-7594 ◽  
Author(s):  
Jaeseok Kim ◽  
Young Jun Yoon ◽  
Yeontae Gim ◽  
Jin Hee Choi ◽  
Hyo Jin Kang ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Physical Characteristics ◽  
Weddell Sea ◽  
New Particle Formation ◽  
Condensation Nuclei ◽  
Source Rate ◽  
The Antarctic

Abstract. The physical characteristics of aerosol particles during particle bursts observed at King Sejong Station in the Antarctic Peninsula from March 2009 to December 2016 were analyzed. This study focuses on the seasonal variation in parameters related to particle formation such as the occurrence, formation rate (FR) and growth rate (GR), condensation sink (CS) and source rate of condensable vapor. The number concentrations during new particle formation (NPF) events varied from 1707 to 83 120 cm−3, with an average of 20 649 ± 9290 cm−3, and the duration of the NPF events ranged from 0.6 to 14.4 h, with a mean of 4.6±1.5 h. The NPF event dominantly occurred during austral summer period (∼72 %). The measured mean values of FR and GR of the aerosol particles were 2.79±1.05 cm−3 s−1 and 0.68±0.27 nm h−1, respectively, showing enhanced rates in the summer season. The mean value of FR at King Sejong Station was higher than that at other sites in Antarctica, at 0.002–0.3 cm−3 s−1, while those of growth rates were relatively similar to the results observed by previous studies, at 0.4–4.3 nm h−1. The derived average values of CS and source rate of condensable vapor were (6.04±2.74)×10-3 s−1 and (5.19±3.51)×104 cm−3 s−1, respectively. The contribution of particle formation to cloud condensation nuclei (CCN) concentration was also investigated. The CCN concentration during the NPF period increased by approximately 11 % compared with the background concentration. In addition, the effects of the origin and pathway of air masses on the characteristics of aerosol particles during a NPF event were determined. The FRs were similar regardless of the origin and pathway, whereas the GRs of particles originating from the Antarctic Peninsula and the Bellingshausen Sea, at 0.77±0.25 and 0.76±0.30 nm h−1, respectively, were higher than those of particles originating from the Weddell Sea (0.41±0.15 nm h−1).

scholarly journals Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

2006 ◽  
Vol 6 (5) ◽  
pp. 9937-9965
Author(s):  
M. Ehn ◽  
T. Petäjä ◽  
H. Aufmhoff ◽  
P. Aalto ◽  
K. Hämeri ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Boreal Forest ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Early Morning ◽  
Particle Formation ◽  
New Particle Formation ◽  
Hygroscopic Growth ◽  
Hygroscopic Properties ◽  
Hygroscopic Particles

Abstract. Freshly formed atmospheric aerosol particles are neither large enough to efficiently scatter incoming solar radiation nor able to act as cloud condensation nuclei. As the particles grow larger, their hygroscopicity determines the limiting size after which they are important in both of the aforementioned processes. The condensing species resulting in growth alter the hygroscopicity of the particles. We have measured hygroscopic growth of aerosol particles present in a boreal forest, along with the very hygroscopic atmospheric trace gas sulfuric acid. The focus was on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with gaseous phase sulfuric acid concentrations. This correlation had a strong size dependency; the smaller the particle, the more condensing sulfuric acid is bound to alter the GF due to initially smaller mass. In addition, water uptake of nucleation mode particles was monitored during new particle formation events and followed during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that initially more hygroscopic particles transformed into less hygroscopic or even hydrophobic particles. A similar behavior was seen also during days with no particle formation, with GF decreasing during the evenings and increasing during early morning. This can be tentatively explained by day- and nighttime differences in the hygroscopicity of condensable vapors.

scholarly journals Variability of air ion concentrations in urban Paris

2015 ◽  
Vol 15 (7) ◽  
pp. 10629-10676 ◽  
Author(s):  
V. N. Dos Santos ◽  
E. Herrmann ◽  
H. E. Manninen ◽  
T. Hussein ◽  
J. Hakala ◽  
...  
Keyword(s):  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Late Summer ◽  
Particle Formation ◽  
Urban Site ◽  
New Particle Formation ◽  
Climatic Effects ◽  
Ion Concentrations ◽  
Ion Size

Abstract. Air ion concentrations influence new particle formation and consequently the global aerosol an cloud condensation nuclei loads. We aimed to evaluate air ion concentrations and characteristics of new particle formation events (NPF) in the megacity Paris, France (Megapoli project). We measured air ion number size distributions (0.8–42 nm) and fine particle number concentrations (> 6 nm) in an urban site of Paris between 26 June 2009 and 4 October 2010. Air ions were size classified as small (0.8–2 nm), intermediate (2–7 nm) and large (7–20 nm). The media concentrations of small and large ions were 670 and 680 cm−3 respectively (sum of positive an negative polarities) whereas the median concentration of intermediate ions was only 20 cm−3, as these ions were mostly present during new particle formation bursts, i.e. when gas-to-particle conversion produced fresh aerosol particles from gas phase precursors. During peaks in traffic-related particle number, the concentrations of small and intermediate ions decreased whereas the concentrations of large ions increased. Seasonal variations affected the ion population differently, with respect to their size and polarity. NPF was observed in 13 the days, being most frequent in spring and late summer (April, May, July and August). The results also suggest that NPF was favoured on the weekends in comparison to workdays, likely due to the lower levels of condensation sinks in the mornings of weekends (CS weekdays 09:00: 18 × 10−3 s−1; CS weekend 09:00: 8 × 10−3 s−1). The median growth rates (GR) of ions during the NPF events varied between 3–7 nm h−1, increasing with the ion size and being higher on workdays than on weekends for intermediate and large ions. The median GR of small ions on the other hand were rather similar on workdays and weekends. In general, NPF bursts changed the diurnal cycle of particle number, intermediate and large ions by causing an extra peak between 09:00 and 14:00. On average, during the NPF bursts the concentrations of intermediate ions were 8.5–10 times higher than on NPF non-event days, depending on the polarity, and the concentrations of large ions and particles were 1.5–1.8 and 1.2 times higher, respectively. Because the median concentrations of intermediate ions were considerably higher on NPF event days in comparison to NPF non-event days, the results indicate that intermediate ion concentrations could be used as an indication for NPF in Paris. The results suggest that NPF was a source of ions and aerosol particles in Paris and therefore contributed to both air quality degradation and climatic effects, especially in the spring and summer.

scholarly journals Variability of air ion concentrations in urban Paris

2015 ◽  
Vol 15 (23) ◽  
pp. 13717-13737 ◽  
Author(s):  
V. N. Dos Santos ◽  
E. Herrmann ◽  
H. E. Manninen ◽  
T. Hussein ◽  
J. Hakala ◽  
...  
Keyword(s):  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Late Summer ◽  
Particle Formation ◽  
Urban Site ◽  
New Particle Formation ◽  
Climatic Effects ◽  
Ion Concentrations ◽  
Ion Size

Abstract. Air ion concentrations influence new particle formation and consequently the global aerosol as potential cloud condensation nuclei. We aimed to evaluate air ion concentrations and characteristics of new particle formation events (NPF) in the megacity of Paris, France, within the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric Pollution and climate effects, and Integrated tools for assessment and mitigation) project. We measured air ion number size distributions (0.8–42 nm) with an air ion spectrometer and fine particle number concentrations (> 6 nm) with a twin differential mobility particle sizer in an urban site of Paris between 26 June 2009 and 4 October 2010. Air ions were size classified as small (0.8–2 nm), intermediate (2–7 nm), and large (7–20 nm). The median concentrations of small and large ions were 670 and 680 cm−3, respectively, (sum of positive and negative polarities), whereas the median concentration of intermediate ions was only 20 cm−3, as these ions were mostly present during new particle formation bursts, i.e. when gas-to-particle conversion produced fresh aerosol particles from gas phase precursors. During peaks in traffic-related particle number, the concentrations of small and intermediate ions decreased, whereas the concentrations of large ions increased. Seasonal variations affected the ion population differently, with respect to their size and polarity. NPF was observed in 13 % of the days, being most frequent in spring and late summer (April, May, July, and August). The results also suggest that NPF was favoured on the weekends in comparison to workdays, likely due to the lower levels of condensation sinks in the mornings of weekends (CS weekdays 09:00: 18 × 10−3 s−1; CS weekend 09:00: 8 × 10−3 s−1). The median growth rates (GR) of ions during the NPF events varied between 3 and 7 nm h−1, increasing with the ion size and being higher on workdays than on weekends for intermediate and large ions. The median GR of small ions on the other hand were rather similar on workdays and weekends. In general, NPF bursts changed the diurnal cycle of particle number as well as intermediate and large ions by causing an extra peak between 09:00 and 14:00. On average, during the NPF bursts the concentrations of intermediate ions were 8.5–10 times higher than on NPF non-event days, depending on the polarity, and the concentrations of large ions and particles were 1.5–1.8 and 1.2 times higher, respectively. Because the median concentrations of intermediate ions were considerably higher on NPF event days in comparison to NPF non-event days, the results indicate that intermediate ion concentrations could be used as an indication for NPF in Paris. The results suggest that NPF was a source of ions and aerosol particles in Paris and therefore contributed to both air quality degradation and climatic effects, especially in the spring and summer.

Particle production in the upper troposphere over the Amazon Basin

2020 ◽  
Author(s):  
Lixia Liu ◽  
Hang Su ◽  
Ulrich Pöschl ◽  
Yafang Cheng
Keyword(s):  
Amazon Basin ◽  
Particle Production ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Dry Season ◽  
New Particle Formation ◽  
High Concentration ◽  
Fine Grid ◽  
Upper Troposphere

<p>Particle production in the upper troposphere has been reported as an important source of aerosol particles and cloud condensation nuclei in pristine environment and tropical regions and exerts significant climate effects. In this work, we develop a new organic nucleation scheme to the WRF-Chem model with extended particle size bins from 1nm to 10μm. We improve on previous coarse-resolution global simulations that approximate the highly oxygenated multifunctional organic compounds (HOMs) in a thermodynamic state by implementing kinetic calculation of HOMs and using fine-grid regional simulations. Sensitivity studies are conducted over the Amazon Basin during the dry season in 2014 to characterize the HOMs-induced new particle formation and identify its key controlling factors in Amazon. The model simulations are evaluated using aircraft observations of profiles of aerosol particles during the 2014 ACRIDICON-CHUVA campaign. We show that the new particle formation occurs mostly at the upper troposphere and modestly in the planetary boundary layer, driven by low temperature and high concentration of biogenic precursors, respectively. Including the HOMs-induced biogenic new particle formation mechanism decreases the model prediction bias of the particle number concentration in the upper troposphere by over 50%, suggesting an important role of the HOMs-induced biogenic new particle formation in the dry season over the Amazon region.</p>

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