Size-resolved aerosol water uptake and cloud condensation nuclei measurements as measured  above a Southeast Asian rainforest during OP3

Abstract. The influence of the properties of fine particles on the formation of clouds and precipitation in the tropical atmosphere is of primary importance to their impacts on radiative forcing and the hydrological cycle. Measurements of aerosol number size distribution, hygroscopicity in both sub- and supersaturated regimes and composition were taken between March and July 2008 in the tropical rainforest in Borneo, Malaysia, marking the first study of this type in an Asian tropical rainforest. Hygroscopic growth factors (GF) at 90% relative humidity (RH) for the dry diameter range D0=32–258 nm, supersaturated water uptake behaviour for the dry diameter range D0=20–300 nm and aerosol chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA), a Droplet Measurement Technologies Cloud Condensation Nuclei counter (CCNc) and an Aerodyne Aerosol Mass Spectrometer (AMS), respectively. The derived hygroscopicty parameter κ ranged from between 0.05–0.37 for the supersaturation range 0.11–0.73% compared to those between 0.17–0.37 for measurements performed at a relative humidity of 90%. In contrast, results from a study with similar methodology performed in the Amazon basin report more similar values for κ, indicating that the aerosol as measured from both sites shows similar hygroscopic properties. However, the derived number of cloud condensation nuclei (NCCN) were much higher than those measured in the Amazon, due to the higher particle number concentrations in the rainforests of Borneo. This first contrast between the two environments may be of substantial importance in describing the impacts of particles in the tropical atmosphere.

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Size-resolved aerosol water uptake and cloud condensation nuclei measurements as measured above a Southeast Asian rainforest during OP3

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-11157-2011 ◽

2011 ◽

Vol 11 (21) ◽

pp. 11157-11174 ◽

Cited By ~ 26

Author(s):

M. Irwin ◽

N. Robinson ◽

J. D. Allan ◽

H. Coe ◽

G. McFiggans

Keyword(s):

Water Uptake ◽

Radiative Forcing ◽

Tropical Rainforest ◽

Fine Particles ◽

Hydrological Cycle ◽

Cloud Condensation Nuclei ◽

Tropical Atmosphere ◽

Condensation Nuclei ◽

Hygroscopic Properties ◽

Diameter Range

Abstract. The influence of the properties of fine particles on the formation of clouds and precipitation in the tropical atmosphere is of primary importance to their impacts on radiative forcing and the hydrological cycle. Measurements of aerosol number size distribution, hygroscopicity in both sub- and supersaturated regimes and composition were taken between March and July 2008 in the tropical rainforest in Borneo, Malaysia, marking the first study of this type in an Asian tropical rainforest. Hygroscopic growth factors (GF) at 90 % relative humidity (RH) for the dry diameter range D0 = 32–258 nm, supersaturated water uptake behaviour for the dry diameter range D0 = 45–300 nm and aerosol chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA), a Droplet Measurement Technologies Cloud Condensation Nuclei counter (CCNc) and an Aerodyne Aerosol Mass Spectrometer (AMS) respectively. The hygroscopicity parameter κ was derived from both CCNc and HTDMA measurements, with the resulting values of κ ranging from 0.05–0.37, and 0.17–0.37, respectively. Although the total range of κ values is in good agreement, there are inconsistencies between CCNc and HTDMA derived κ values at different dry diameters. Results from a study with similar methodology performed in the Amazon rainforest report values for κ within a similar range to those reported in this work, indicating that the aerosol as measured from both sites shows similar hygroscopic properties. However, the derived number of cloud condensation nuclei (NCCN) were much higher in the present experiment than the Amazon, resulting in part from the increased total particle number concentrations observed in the Bornean rainforest. This contrast between the two environments may be of substantial importance in describing the impacts of particles in the tropical atmosphere.

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New evidence of soot particles affecting past and future cloud formation and climate

10.5194/egusphere-egu2020-3635 ◽

2020 ◽

Author(s):

Ulrike Lohmann ◽

Franz Friebel ◽

Zamin A. Kanji ◽

Fabian Mahrt ◽

Amewu A. Mensah ◽

...

Keyword(s):

Radiative Forcing ◽

Hydrological Cycle ◽

Global Climate ◽

Cloud Condensation Nuclei ◽

Critical Role ◽

Carbon Dioxide Concentration ◽

Radiative Properties ◽

Cloud Formation ◽

Condensation Nuclei ◽

Soot Particles

Clouds play a critical role in the hydrological cycle and modulating the Earth&#8217;s climate via precipitation and radiative forcing. Aerosol particles acting as cloud condensation nuclei and ice nucleating particles aid in cloud formation, shaping their microphysical structure. Previously thought to be unimportant for cloud formation, soot particles that undergo oxidation by ozone and/or aging with aqueous sulfuric acid result in being both good centers for cloud droplets and ice crystals formation. However, the associated changes in cloud radiative properties and the consequences for Earth&#8217;s climate remain uncertain, because these processes have not been considered in global climate models. Here we present both past and future global climate simulations, which for the first time consider the effect of such aged soot particles as cloud condensation nuclei and ice nucleating particles. Our results constitute the first evidence that aging of soot particles produce a 0.2 to 0.25 Wm-2 less negative shortwave indirect aerosol forcing compared to previous estimates. We also conducted equilibrium climate sensitivity simulations representing a future warmer climate in which the carbon dioxide concentration is doubled compared to pre-industrial levels. Accounting for these soot aging processes significantly exacerbates the global mean surface temperature increase by 0.4 to 0.5 K. Thus, reducing emissions of soot particles will be beneficial for many aspects including air pollution and future climate.&#160;

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Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-7891-2010 ◽

2010 ◽

Vol 10 (16) ◽

pp. 7891-7906 ◽

Cited By ~ 79

Author(s):

Z. Jurányi ◽

M. Gysel ◽

E. Weingartner ◽

P. F. DeCarlo ◽

L. Kammermann ◽

...

Keyword(s):

Chemical Composition ◽

Hydrological Cycle ◽

Cloud Condensation Nuclei ◽

Sensitivity Study ◽

Research Station ◽

Condensation Nuclei ◽

Composition Data ◽

Particle Mobility ◽

Kohler Theory ◽

Highly Correlated

Abstract. Atmospheric aerosol particles are able to act as cloud condensation nuclei (CCN) and are therefore important for the climate and the hydrological cycle, but their properties are not fully understood. Total CCN number concentrations at 10 different supersaturations in the range of SS=0.12–1.18% were measured in May 2008 at the remote high alpine research station, Jungfraujoch, Switzerland (3580 m a.s.l.). In this paper, we present a closure study between measured and predicted CCN number concentrations. CCN predictions were done using dry number size distribution (scanning particle mobility sizer, SMPS) and bulk chemical composition data (aerosol mass spectrometer, AMS, and multi-angle absorption photometer, MAAP) in a simplified Köhler theory. The predicted and the measured CCN number concentrations agree very well and are highly correlated. A sensitivity study showed that the temporal variability of the chemical composition at the Jungfraujoch can be neglected for a reliable CCN prediction, whereas it is important to know the mean chemical composition. The exact bias introduced by using a too low or too high hygroscopicity parameter for CCN prediction was further quantified and shown to be substantial for the lowest supersaturation. Despite the high average organic mass fraction (~45%) in the fine mode, there was no indication that the surface tension was substantially reduced at the point of CCN activation. A comparison between hygroscopicity tandem differential mobility analyzer (HTDMA), AMS/MAAP, and CCN derived κ values showed that HTDMA measurements can be used to determine particle hygroscopicity required for CCN predictions if no suitable chemical composition data are available.

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Hygroscopic properties and cloud condensation nuclei activity of atmospheric aerosols under the influences of Asian continental outflow and new particle formation at a coastal site in eastern Asia

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-5911-2020 ◽

2020 ◽

Vol 20 (10) ◽

pp. 5911-5922 ◽

Cited By ~ 4

Author(s):

Hing Cho Cheung ◽

Charles Chung-Kuang Chou ◽

Celine Siu Lan Lee ◽

Wei-Chen Kuo ◽

Shuenn-Chin Chang

Keyword(s):

Chemical Composition ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

Number Concentration ◽

Pollution Sources ◽

New Particle Formation ◽

Condensation Nuclei ◽

Air Masses ◽

Hygroscopic Properties ◽

Aerosol Hygroscopicity

Abstract. The chemical composition of fine particulate matter (PM2.5), the size distribution and number concentration of aerosol particles (NCN), and the number concentration of cloud condensation nuclei (NCCN) were measured at the northern tip of Taiwan during an intensive observation experiment from April 2017 to March 2018. The parameters of aerosol hygroscopicity (i.e., activation ratio, activation diameter and kappa of CCN) were retrieved from the measurements. Significant variations were found in the hygroscopicity of aerosols (kappa – κ – of 0.18–0.56, for water vapor supersaturation – SS – of 0.12 %–0.80 %), which were subject to various pollution sources, including aged air pollutants originating in eastern and northern China and transported by the Asian continental outflows and fresh particles emitted from local sources and distributed by land–sea breeze circulations as well as produced by processes of new particle formation (NPF). Cluster analysis was applied to the back trajectories of air masses to investigate their respective source regions. The results showed that aerosols associated with Asian continental outflows were characterized by lower NCN and NCCN values and by higher kappa values of CCN, whereas higher NCN and NCCN values with lower kappa values of CCN were observed in the aerosols associated with local air masses. Besides, it was revealed that the kappa value of CCN exhibited a decrease during the early stage of an event of new particle formation, which turned to an increasing trend over the later period. The distinct features in the hygroscopicity of aerosols were found to be consistent with the characteristics in the chemical composition of PM2.5. This study has depicted a clear seasonal characteristic of hygroscopicity and CCN activity under the influence of a complex mixture of pollutants from different regional and/or local pollution sources. Nevertheless, the mixing state and chemical composition of the aerosols critically influence the aerosol hygroscopicity, and further investigations are necessary to elucidate the atmospheric processing involved in the CCN activation in coastal areas.

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Wintertime new particle formation and its contribution to cloud condensation nuclei in the Northeastern United States

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-2591-2020 ◽

2020 ◽

Vol 20 (4) ◽

pp. 2591-2601

Author(s):

Fangqun Yu ◽

Gan Luo ◽

Arshad Arjunan Nair ◽

James J. Schwab ◽

James P. Sherman ◽

...

Keyword(s):

United States ◽

Particle Number ◽

Hydrological Cycle ◽

Cloud Condensation Nuclei ◽

Particle Formation ◽

New Particle Formation ◽

Northeastern United States ◽

Condensation Nuclei ◽

Upper Troposphere ◽

Inorganic Species

Abstract. Atmospheric particles can act as cloud condensation nuclei (CCN) and modify cloud properties and precipitation and thus indirectly impact the hydrological cycle and climate. New particle formation (NPF or nucleation), frequently observed at locations around the globe, is an important source of ultrafine particles and CCN in the atmosphere. In this study, wintertime NPF over the Northeastern United States (NEUS) is simulated with WRF-Chem coupled with a size-resolved (sectional) advanced particle microphysics (APM) model. Model-simulated variations in particle number concentrations during a 2-month period (November–December 2013) are in agreement with corresponding measurements taken at Pinnacle State Park (PSP), New York, and Appalachian State University (APP), North Carolina. We show that, even during wintertime, regional nucleation occurs and contributes significantly to ultrafine-particle and CCN number concentrations over the NEUS. The model shows that, due to low biogenic emissions during this period, wintertime regional nucleation is solely controlled by inorganic species and the newly developed ternary ion-mediated nucleation scheme is able to capture the variations in observed particle number concentrations (ranging from ∼200 to 20 000 cm−3) at both PSP and APP. Total particle and CCN number concentrations dramatically increase following NPF events and have the highest values over the Ohio Valley region, where elevated [SO2] is sustained by power plants. Secondary particles dominate particle number abundance over the NEUS, and their fraction increases with altitude from ≳85 % near the surface to ≳95 % in the upper troposphere. The secondary fraction of CCN also increases with altitude, from 20 %–50 % in the lower boundary layer to 50 %–60 % in the middle troposphere to 70 %–85 % in the upper troposphere.

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Hygroscopic behavior and chemical composition evolution of internally mixed aerosols composed of oxalic acid and ammonium sulfate

10.5194/acp-2017-454 ◽

2017 ◽

Author(s):

Xiaowei Wang ◽

Bo Jing ◽

Fang Tan ◽

Jiabi Ma ◽

Yunhong Zhang ◽

...

Keyword(s):

Growth Factors ◽

Chemical Composition ◽

Relative Humidity ◽

Oxalic Acid ◽

Ammonium Sulfate ◽

Water Uptake ◽

Atmospheric Environment ◽

Dehydration Process ◽

Hygroscopic Properties ◽

Ammonium Hydrogen

Abstract. Although water uptake of aerosols plays an important role in the atmospheric environment, the effects of interactions between components on chemical composition and hygroscopicity of aerosols are still not well constrained. The hygroscopic properties and phase transformation of oxalic acid (OA) and mixed particles composed of ammonium sulfate (AS) and OA with different organic to inorganic molar ratios (OIRs) have been investigated by using confocal Raman spectroscopy. It is found that OA droplets first crystallize to form oxalic acid dihydrate at 77 % relative humidity (RH), and further lose crystalline water to convert into anhydrous oxalic acid around 5 % RH during the dehydration process. The deliquescence and efflorescence point for AS is determined to be 80.1 ± 1.5 % RH and 44.3 ± 2.5 % RH, respectively. The observed efflorescence relative humidity (ERH) for mixed OA/AS droplets with OIRs of 1:3, 1:1 and 3:1 is 34.4 ± 2.0 % RH, 44.3 ± 2.5 % RH and 64.4 ± 3.0 % RH, respectively, indicating the elevated OA content appears to favor the crystallization of mixed systems at higher RH. However, the partial deliquescence relative humidity (DRH) for mixed OA/AS particles with OIR of 1:3 and 1:1 is observed to occur at 81.1 ± 1.5 % RH and 77 ± 1.0 % RH, respectively. The Raman spectra of mixed OA/AS droplets indicate the formation of ammonium hydrogen oxalate (NH4HC2O4) and ammonium hydrogen sulfate (NH4HSO4) from interactions between OA and AS in aerosols after slow dehydration process in the time scale of hours, which considerably influence the subsequent deliquescence behavior of internally mixed particles with different OIRs. The mixed OA/AS particles with 3:1 ratio exhibit no deliquescence transition over the RH range studied due to the considerable transformation of (NH4)2SO4 into nonhygroscopic NH4HC2O4. Although the hygroscopic growth of mixed OA/AS droplets is comparable to that of AS or OA at high RH during the dehydration process, Raman growth factors of mixed particles after deliquescence are substantially lower than those of mixed OA/AS droplets during the efflorescence process and further decrease with elevated OA content. The discrepancies for Raman growth factors of mixed OA/AS particles between the dehydration and hydration process at high RH can be attributed to the significant formation of NH4HC2O4 and residual OA, which remain solid at high RH and thus result in less water uptake of mixed particles. These findings improve the understanding of the role of reactions between dicarboxylic acid and inorganic salt in the chemical and physical properties of aerosol particles, and might have important implications for atmospheric chemistry.

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The analysis of size-segregated cloud condensation nuclei counter (CCNC) data and its implications for cloud droplet activation

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-10285-2013 ◽

2013 ◽

Vol 13 (20) ◽

pp. 10285-10301 ◽

Cited By ~ 45

Author(s):

M. Paramonov ◽

P. P. Aalto ◽

A. Asmi ◽

N. Prisle ◽

V.-M. Kerminen ◽

...

Keyword(s):

Cloud Condensation Nuclei ◽

Critical Diameter ◽

Cloud Droplet ◽

Condensation Nuclei ◽

Ambient Aerosol ◽

Cloud Processing ◽

Aerosol Mass ◽

Diurnal Patterns ◽

Hygroscopic Properties ◽

Boreal Environment

Abstract. Ambient aerosol, CCN (cloud condensation nuclei) and hygroscopic properties were measured with a size-segregated CCNC (cloud condensation nuclei counter) in a boreal environment of southern Finland at the SMEAR (Station for Measuring Ecosystem-Atmosphere Relations) II station. The instrumental setup operated at five levels of supersaturation S covering a range from 0.1–1% and measured particles with a size range of 20–300 nm; a total of 29 non-consecutive months of data are presented. The median critical diameter Dc ranged from 150 nm at S of 0.1% to 46 nm at S of 1.0%. The median aerosol hygroscopicity parameter κ ranged from 0.41 at S of 0.1% to 0.14 at S of 1.0%, indicating that ambient aerosol in Hyytiälä is less hygroscopic than the global continental or European continental averages. It is, however, more hygroscopic than the ambient aerosol in an Amazon rainforest, a European high Alpine site or a forested mountainous site. A fairly low hygroscopicity in Hyytiälä is likely a result of a large organic fraction present in the aerosol mass comparative to other locations within Europe. A considerable difference in particle hygroscopicity was found between particles smaller and larger than ~100 nm in diameter, possibly pointing out to the effect of cloud processing increasing κ of particles > 100 nm in diameter. The hygroscopicity of the smaller, ~50 nm particles did not change seasonally, whereas particles with a diameter of ~150 nm showed a decreased hygroscopicity in the summer, likely resulting from the increased VOC emissions of the surrounding boreal forest and secondary organic aerosol (SOA) formation. For the most part, no diurnal patterns of aerosol hygroscopic properties were found. Exceptions to this were the weak diurnal patterns of small, ~50 nm particles in the spring and summer, when a peak in hygroscopicity around noon was observed. No difference in CCN activation and hygroscopic properties was found on days with or without atmospheric new particle formation. During all seasons, except summer, a CCN-inactive fraction was found to be present, rendering the aerosol of 75–300 nm in diameter as internally mixed in the summer and not internally mixed for the rest of the year.

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Incorporation of advanced aerosol activation treatments into CESM/CAM5: model evaluation and impacts on aerosol indirect effects

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-7485-2014 ◽

2014 ◽

Vol 14 (14) ◽

pp. 7485-7497 ◽

Cited By ~ 33

Author(s):

B. Gantt ◽

J. He ◽

X. Zhang ◽

Y. Zhang ◽

A. Nenes

Keyword(s):

Indirect Effects ◽

Radiative Forcing ◽

Cloud Condensation Nuclei ◽

Condensation Nuclei ◽

Activation Kinetics ◽

Aerosol Cloud ◽

Model Version ◽

Cloud Properties ◽

Aerosol Cloud Interactions ◽

Aerosol Activation

Abstract. One of the greatest sources of uncertainty in the science of anthropogenic climate change is from aerosol–cloud interactions. The activation of aerosols into cloud droplets is a direct microphysical linkage between aerosols and clouds; parameterizations of this process link aerosol with cloud condensation nuclei (CCN) and the resulting indirect effects. Small differences between parameterizations can have a large impact on the spatiotemporal distributions of activated aerosols and the resulting cloud properties. In this work, we incorporate a series of aerosol activation schemes into the Community Atmosphere Model version 5.1.1 within the Community Earth System Model version 1.0.5 (CESM/CAM5) which include factors such as insoluble aerosol adsorption and giant cloud condensation nuclei (CCN) activation kinetics to understand their individual impacts on global-scale cloud droplet number concentration (CDNC). Compared to the existing activation scheme in CESM/CAM5, this series of activation schemes increase the computation time by ~10% but leads to predicted CDNC in better agreement with satellite-derived/in situ values in many regions with high CDNC but in worse agreement for some regions with low CDNC. Large percentage changes in predicted CDNC occur over desert and oceanic regions, owing to the enhanced activation of dust from insoluble aerosol adsorption and reduced activation of sea spray aerosol after accounting for giant CCN activation kinetics. Comparison of CESM/CAM5 predictions against satellite-derived cloud optical thickness and liquid water path shows that the updated activation schemes generally improve the low biases. Globally, the incorporation of all updated schemes leads to an average increase in column CDNC of 150% and an increase (more negative) in shortwave cloud forcing of 12%. With the improvement of model-predicted CDNCs and better agreement with most satellite-derived cloud properties in many regions, the inclusion of these aerosol activation processes should result in better predictions of radiative forcing from aerosol–cloud interactions.

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Moisture uptake in nanocellulose: the effects of relative humidity, temperature and degree of crystallinity

Cellulose ◽

10.1007/s10570-021-04099-9 ◽

2021 ◽

Author(s):

Mohit Garg ◽

Varvara Apostolopoulou-Kalkavoura ◽

Mathieu Linares ◽

Tahani Kaldéus ◽

Eva Malmström ◽

...

Keyword(s):

Relative Humidity ◽

Water Uptake ◽

Thermal Insulation ◽

Cellulose Nanofibrils ◽

Degree Of Crystallinity ◽

Crystalline Cellulose ◽

Moisture Uptake ◽

Amorphous Cellulose ◽

Hygroscopic Properties ◽

Cellulose Nanomaterials

AbstractFoams made from cellulose nanomaterials are highly porous and possess excellent mechanical and thermal insulation properties. However, the moisture uptake and hygroscopic properties of these materials need to be better understood for their use in biomedical and bioelectronics applications, in humidity sensing and thermal insulation. In this work, we present a combination of hybrid Grand Canonical Monte Carlo and Molecular Dynamics simulations and experimental measurements to investigate the moisture uptake within nanocellulose foams. To explore the effect of surface modification on moisture uptake we used two types of celluloses, namely TEMPO-oxidized cellulose nanofibrils and carboxymethylated cellulose nanofibrils. We find that the moisture uptake in both the cellulose nanomaterials increases with increasing relative humidity (RH) and decreases with increasing temperature, which is explained using the basic thermodynamic principles. The measured and calculated moisture uptake in amorphous cellulose (for a given RH or temperature) is higher as compared to crystalline cellulose with TEMPO- and CM-modified surfaces. The high water uptake of amorphous cellulose films is related to the formation of water-filled pores with increasing RH. The microscopic insight of water uptake in nanocellulose provided in this study can assist the design and fabrication of high-performance cellulose materials with improved properties for thermal insulation in humid climates or packaging of water sensitive goods. Graphic abstract

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Cloud condensation nuclei production associated with atmospheric nucleation: a synthesis based on existing literature and new results

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-12037-2012 ◽

2012 ◽

Vol 12 (24) ◽

pp. 12037-12059 ◽

Cited By ~ 180

Author(s):

V.-M. Kerminen ◽

M. Paramonov ◽

T. Anttila ◽

I. Riipinen ◽

C. Fountoukis ◽

...

Keyword(s):

Radiative Forcing ◽

Large Scale ◽

Cloud Condensation Nuclei ◽

Large Fraction ◽

Scientific Information ◽

Scale Model ◽

Condensation Nuclei ◽

Uncertainty Range ◽

Model Studies ◽

Atmospheric Nucleation

Abstract. This paper synthesizes the available scientific information connecting atmospheric nucleation with subsequent cloud condensation nuclei (CCN) formation. We review both observations and model studies related to this topic, and discuss the potential climatic implications. We conclude that CCN production associated with atmospheric nucleation is both frequent and widespread phenomenon in many types of continental boundary layers, and probably also over a large fraction of the free troposphere. The contribution of nucleation to the global CCN budget spans a relatively large uncertainty range, which, together with our poor understanding of aerosol-cloud interactions, results in major uncertainties in the radiative forcing by atmospheric aerosols. In order to better quantify the role of atmospheric nucleation in CCN formation and Earth System behavior, more information is needed on (i) the factors controlling atmospheric CCN production and (ii) the properties of both primary and secondary CCN and their interconnections. In future investigations, more emphasis should be put on combining field measurements with regional and large-scale model studies.

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