scholarly journals Aerodynamic size-resolved composition and cloud condensation nuclei properties of aerosols in Beijing suburban region

2021 ◽  
Author(s):  
Chenjie Yu ◽  
Dantong Liu ◽  
Kang Hu ◽  
Ping Tian ◽  
Yangzhou Wu ◽  
...  
Keyword(s):  
Particle Size ◽  
Deposition Rate ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Atmospheric Composition ◽  
Radiation Absorption ◽  
Condensation Nuclei ◽  
Pollution Levels ◽  
Online Measurements ◽  
Droplet Activation

Abstract. The size-resolved physiochemical properties of aerosols determine their atmospheric lifetime, cloud interactions, and the deposition rate on human respiratory system, however most atmospheric composition studies tend to evaluate these properties in bulk. This study investigated size-resolved constituents of aerosols on mass and number basis, and their droplet activation properties, by coupling a suite of online measurements with an aerosol aerodynamic classifier (AAC) based on aerodynamic diameter (Da) in Pinggu, a suburb of Beijing. While organic matter accounted for a large fraction of mass, a higher contribution of particulate nitrate at larger sizes (Da > 300 nm) was found under polluted cases. By applying the mixing state of refractory black carbon containing particles (rBCc) and composition-dependent densities, aerosols including rBCc were confirmed nearly spherical at Da > 300 nm. Importantly, the number fraction of rBCc was found to increase with Da at all pollution levels. The number fraction of rBC is found to increase from ~3 % at ~90 nm to ~15 % at ~1000 nm, and this increasing rBC number fraction may be caused by the coagulation during atmospheric aging. The droplet activation diameter at a water supersaturation of 0.2 % was 112 ± 6 nm and 193 ± 41 nm for all particles with Da smaller than 1 μm (PM1) and rBCc respectively. As high as 52 ± 6 % of rBCc and 50 ± 4 % of all PM1 particles in number could be activated under heavy pollution due to enlarged particle size, which could be predicted by applying the volume-mixing of substance hygroscopicity within rBCc. As rBCc contributes to the quantity of aerosols at larger particle size, these thickly coated rBC may contribute to the radiation absorption significantly or act as an important source of cloud condensation nuclei (CCN). This size regime may also exert important health effects due to their higher deposition rate.

scholarly journals Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania

2015 ◽  
Vol 15 (23) ◽  
pp. 13393-13411 ◽  
Author(s):  
S. J. Lawson ◽  
M. D. Keywood ◽  
I. E. Galbally ◽  
J. L. Gras ◽  
J. M. Cainey ◽  
...  
Keyword(s):  
Particle Size ◽  
Biomass Burning ◽  
Cloud Condensation Nuclei ◽  
Trace Gases ◽  
Particle Growth ◽  
Dominant Mode ◽  
Condensation Nuclei ◽  
Substantial Impact ◽  
Marine Air ◽  
Cape Grim

Abstract. Biomass burning (BB) plumes were measured at the Cape Grim Baseline Air Pollution Station during the 2006 Precursors to Particles campaign, when emissions from a fire on nearby Robbins Island impacted the station. Measurements made included non-methane organic compounds (NMOCs) (PTR-MS), particle number size distribution, condensation nuclei (CN) > 3 nm, black carbon (BC) concentration, cloud condensation nuclei (CCN) number, ozone (O3), methane (CH4), carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), nitrous oxide (N2O), halocarbons and meteorology. During the first plume strike event (BB1), a 4 h enhancement of CO (max ~ 2100 ppb), BC (~ 1400 ng m-3) and particles > 3 nm (~ 13 000 cm-3) with dominant particle mode of 120 nm were observed overnight. A wind direction change lead to a dramatic reduction in BB tracers and a drop in the dominant particle mode to 50 nm. The dominant mode increased in size to 80 nm over 5 h in calm sunny conditions, accompanied by an increase in ozone. Due to an enhancement in BC but not CO during particle growth, the presence of BB emissions during this period could not be confirmed. The ability of particles > 80 nm (CN80) to act as CCN at 0.5 % supersaturation was investigated. The ΔCCN / ΔCN80 ratio was lowest during the fresh BB plume (56 ± 8 %), higher during the particle growth period (77 ± 4 %) and higher still (104 ± 3 %) in background marine air. Particle size distributions indicate that changes to particle chemical composition, rather than particle size, are driving these changes. Hourly average CCN during both BB events were between 2000 and 5000 CCN cm-3, which were enhanced above typical background levels by a factor of 6–34, highlighting the dramatic impact BB plumes can have on CCN number in clean marine regions. During the 29 h of the second plume strike event (BB2) CO, BC and a range of NMOCs including acetonitrile and hydrogen cyanide (HCN) were clearly enhanced and some enhancements in O3 were observed (ΔO3 / ΔCO 0.001–0.074). A short-lived increase in NMOCs by a factor of 10 corresponded with a large CO enhancement, an increase of the NMOC / CO emission ratio (ER) by a factor of 2–4 and a halving of the BC / CO ratio. Rainfall on Robbins Island was observed by radar during this period which likely resulted in a lower fire combustion efficiency, and higher emission of compounds associated with smouldering. This highlights the importance of relatively minor meteorological events on BB emission ratios. Emission factors (EFs) were derived for a range of trace gases, some never before reported for Australian fires, (including hydrogen, phenol and toluene) using the carbon mass balance method. This provides a unique set of EFs for Australian coastal heathland fires. Methyl halide EFs were higher than EFs reported from other studies in Australia and the Northern Hemisphere which is likely due to high halogen content in vegetation on Robbins Island. This work demonstrates the substantial impact that BB plumes can have on the composition of marine air, and the significant changes that can occur as the plume interacts with terrestrial, aged urban and marine emission sources.

scholarly journals Versatile Aerosol Concentration Enrichment System (VACES) operating as a Cloud Condensation Nuclei (CCN) concentrator. Development and laboratory characterization

2019 ◽  
Author(s):  
Carmen Dameto de España ◽  
Gerhard Steiner ◽  
Harald Schuh ◽  
Constantinos Sioutas ◽  
Regina Hitzenberger
Keyword(s):  
Particle Size ◽  
Atmospheric Aerosol ◽  
Continuous Flow ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Meteorological Conditions ◽  
Condensation Nuclei ◽  
Laboratory Characterization ◽  
Condenser Temperature ◽  
Original Size

Abstract. The ability of atmospheric aerosol particles to act as cloud condensation nuclei (CCN) depends on many factors, including particle size, chemical composition, and meteorological conditions. To expand our knowledge on CCN, it is essential to understand the factors leading to CCN activation. For this purpose a versatile aerosol concentrator enrichment system (VACES) has been modified to select CCN at different supersaturations. The VACES enables to sample CCN particles without altering their chemical and physical properties. The redesigned VACES enriches CCN particles by first passing the aerosol flow to a new saturator and then to a condenser. The activated particles are concentrated by an inertial virtual impactor, and then can be returned to their original size by diffusion-drying. For the calibration, the saturator temperature was fixed at 52 °C and the condenser temperature range was altered from 5 °C to 25 °C to obtain activation curves for NaCl particles of different sizes. Critical water vapour supersaturations can be calculated using the 50 % cutpoint of these curves. Calibration results have also shown that CCN concentrations can be enriched by a factor of approx. 17, which is in agreement with the experimentally determined enrichment factor of the original VACES. The advantage of the re-designed VACES over conventional CCN counters (both static and continuous flow instruments) lies in the substantial enrichment of activated CCN which facilitates further chemical analysis.

scholarly journals Technical note: A method for measuring size-resolved CCN in the atmosphere

2006 ◽  
Vol 6 (3) ◽  
pp. 4879-4895 ◽  
Author(s):  
G. P. Frank ◽  
U. Dusek ◽  
M. O. Andreae
Keyword(s):  
Particle Size ◽  
Water Vapor ◽  
Size Range ◽  
Cloud Condensation Nuclei ◽  
Technical Note ◽  
Condensation Nuclei ◽  
Ambient Aerosols ◽  
Condensation Particle Counter ◽  
Set Up ◽  
Vapor Supersaturation

Abstract. We present a method to investigate cloud condensation nuclei (CCN) concentrations and activation efficiencies as a function of two independent variables, aerosol particle size and water vapor supersaturation. To date, most ambient CCN measurements have been made as the integral (total) CCN concentration as a function of water vapor supersaturation only. However, since CCN properties of aerosol particles are strongly dependent on particle size, as well as on chemical composition, which commonly varies with particle size, more detailed measurements can provide additional important information about the CCN activation. With size-resolved measurements, the effect of particle size on CCN activity can be kept constant, which makes it possible to directly assess the influence of particle chemistry. The instrumental set-up consists of a differential mobility analyzer (DMA) to select particles of a known size, within a narrow size range. A condensation nuclei (CN) counter (condensation particle counter, CPC) is used to count the total number of particles in that size range, and a CCN counter is used to count the number of CCN as a function of supersaturation, in that same size range. The activation efficiency, expressed as CCN/CN ratios, can thus directly be calculated as a function of particle size and supersaturation. We present examples of the application of this technique, using salt and smoke aerosols produced in the laboratory as well as ambient aerosols.

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

2012 ◽  
Vol 12 (24) ◽  
pp. 12037-12059 ◽  
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.

scholarly journals Size-resolved cloud condensation nuclei (CCN) activity and closure analysis at the HKUST Supersite in Hong Kong

2014 ◽  
Vol 14 (18) ◽  
pp. 10267-10282 ◽  
Author(s):  
J. W. Meng ◽  
M. C. Yeung ◽  
Y. J. Li ◽  
B. Y. L. Lee ◽  
C. K. Chan
Keyword(s):  
Particle Size ◽  
Hong Kong ◽  
Atmospheric Aerosols ◽  
Cloud Condensation Nuclei ◽  
Particle Diameter ◽  
Volume Ratio ◽  
Condensation Nuclei ◽  
Mixing State ◽  
Scanning Mobility Particle Sizer ◽  
The Mean

Abstract. The cloud condensation nuclei (CCN) properties of atmospheric aerosols were measured on 1–30 May 2011 at the HKUST (Hong Kong University of Science and Technology) Supersite, a coastal site in Hong Kong. Size-resolved CCN activation curves, the ratio of number concentration of CCN (NCCN) to aerosol concentration (NCN) as a function of particle size, were obtained at supersaturation (SS) = 0.15, 0.35, 0.50, and 0.70% using a DMT (Droplet Measurement Technologies) CCN counter (CCNc) and a TSI scanning mobility particle sizer (SMPS). The mean bulk size-integrated NCCN ranged from ~500 cm−3 at SS = 0.15% to ~2100 cm−3 at SS = 0.70%, and the mean bulk NCCN / NCN ratio ranged from 0.16 at SS = 0.15% to 0.65 at SS = 0.70%. The average critical mobility diameters (D50) at SS = 0.15, 0.35, 0.50, and 0.70% were 116, 67, 56, and 46 nm, respectively. The corresponding average hygroscopic parameters (κCCN) were 0.39, 0.36, 0.31, and 0.28. The decrease in κCCN can be attributed to the increase in organic to inorganic volume ratio as particle size decreases, as measured by an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The κCCN correlates reasonably well with κAMS_SR based on size-resolved AMS measurements: κAMS_SR = κorg × forg + κinorg × finorg, where forg and finorg are the organic and inorganic volume fractions, respectively, κorg = 0.1 and κinorg = 0.6, with a R2 of 0.51. In closure analysis, NCCN was estimated by integrating the measured size-resolved NCN for particles larger than D50 derived from κ assuming internal mixing state. Estimates using κAMS_SR show that the measured and predicted NCCN were generally within 10% of each other at all four SS. The deviation increased to 26% when κAMS was calculated from bulk PM1 AMS measurements of particles because PM1 was dominated by particles of 200 to 500 nm in diameter, which had a larger inorganic fraction than those of D50 (particle diameter < 200 nm). A constant κ = 0.33 (the average value of κAMS_SR over the course of campaign) was found to give an NCCN prediction within 12% of the actual measured values. We also compared NCCN estimates based on the measured average D50 and the average size-resolved CCN activation ratio to examine the relative importance of hygroscopicity and mixing state. NCCN appears to be relatively more sensitive to the mixing state and hygroscopicity at a high SS = 0.70% and a low SS = 0.15%, respectively.

scholarly journals Relationships between particles, cloud condensation nuclei and cloud droplet activation during the third Pallas Cloud Experiment

2012 ◽  
Vol 12 (6) ◽  
pp. 13691-13732
Author(s):  
T. Anttila ◽  
D. Brus ◽  
A. Jaatinen ◽  
A.-P. Hyvärinen ◽  
N. Kivekäs ◽  
...  
Keyword(s):  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Droplet Surface ◽  
The Arctic ◽  
Condensation Nuclei ◽  
Cloud Droplets ◽  
The Third ◽  
Droplet Activation ◽  
Experimental Values

Abstract. Concurrent measurement of aerosols, cloud condensation nuclei (CCN) and cloud droplet activation were carried out as a part of the third Pallas Cloud Experiment (PaCE-3) which took place at a ground based site located on northern Finland during the autumn of 2009. In this study, we investigate relationships between the aerosol properties, CCN and size resolved cloud droplet activation. During the investigated cloudy periods, the inferred number of cloud droplets (CDNC) varied typically between 50 and 150 cm−3 and displayed a linear correlation both with the number of particles having sizes over 100 nm and with the CCN concentrations at 0.4% supersaturation. Furthermore, the diameter corresponding to the 50% activation fraction, D50, was generally in the range of 80 to 120 nm. The measured CCN concentrations were compared with predictions of a numerical model which used the measured size distribution and size resolved hygroscopicity as input. Assuming that the droplet surface tension is equal to that of water, the measured and predicted CCN concentrations were generally within 30%. We also simulated size dependent cloud droplet activation with a previously developed air parcel model. By forcing the model to reproduce the experimental values of CDNC, adiabatic estimates for the updraft velocity and the maximum supersaturation reached in the clouds were derived. Performed sensitivity studies showed further that the observed variability in CDNC was driven mainly by changes in the particle size distribution while the variations in the updraft velocity and hygroscopicity contributed to a lesser extent. The results of the study corroborate conclusions of previous studies according to which the number of cloud droplets formed in clean air masses close to the Arctic is determined mainly by the number of available CCN.

scholarly journals FABRICATION OF 2-5 µM HYGROSCOPIC SEEDING MATERIAL FOR RAIN ENHANCEMENT PURPOSES

2021 ◽  
Vol 22 (1) ◽  
pp. 35-39
Author(s):  
Dini Harsanti ◽  
Krisna Adhitya ◽  
Safrizal Safrizal
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Condensation Nuclei ◽  
Seeding Material ◽  
Rough Milling ◽  
Jet Milling ◽  
Scanning Electron

Abstract Hygroscopic cloud seeding, which uses giant cloud condensation nuclei (GCCN) particles with diameters between 2-5 µm, has been known to be 100 times more effective compared to those that use hygroscopic flares. Micronisation through jet milling has been recognized as the most common and ubiquitous method used to obtain particles with such a narrow size (2-5 µm) distribution. This research has successfully developed and identified 2-5 µm NaCl powders mixed with 10% cab-o-sil anticaking agent and 2 (two) times jet milling frequency as a potential GCCN (hygroscopic) seeding material. We use a combination of jet mill micronisation, rough milling with a Cross-Beather Mill, and analytical sieving to produce powders with those mentioned above (2-5 µm) size distribution. We varied the anticaking agent percentage in the mixture and the jet milling process frequency to identify which parameters would result in the 2-5 µm size distribution. We then confirmed the micronisation results particle size distribution with a particle size analyzer (PSA) and its morphology with a scanning electron microscope (SEM) machine. The materials with the 10% cab-o-sil agent mixture were confirmed to have the aforementioned size distribution from the characterization results. Intisari Penyemaian awan higroskopis menggunakan partikel giant cloud condensation nuclei (GCCN) dengan diameter 2-5 m telah diketahui 100 kali lebih efektif dibandingkan dengan yang menggunakan flare higroskopis. Mikronisasi melalui jet milling telah dikenal sebagai metode yang paling umum dan banyak digunakan untuk mendapatkan partikel dengan distribusi ukuran sempit (2-5 µm). Penelitian ini berhasil mengembangkan dan mengidentifikasi serbuk NaCl 2-5 µm yang dicampur dengan 10% anti gumpal berupa Cab-O-Sil dan frekuensi jet milling 2 (dua) kali sebagai bahan penyemaian GCCN (higroskopis) potensial. Pada penelitian ini telah digunakan kombinasi mikronisasi jet mill, penggilingan kasar dengan Cross-Beather Mill, dan ayakan analitik untuk menghasilkan serbuk dengan distribusi ukuran yang disebutkan di atas (2-5 µm). Telah divariasikan pula persentase bahan anti gumpal dalam campuran dan frekuensi proses jet milling untuk mengidentifikasi parameter yang akan menghasilkan distribusi ukuran 2-5 µm. Distribusi ukuran partikel hasil mikronisasi tersebut kemudian dikonfirmasi dengan alat analisa ukuran partikel (PSA) dan morfologinya dengan mesin scanning electron microscope (SEM). Dari hasil karakterisasi, material dengan campuran anti gumpal Cab-O-Sil sebanyak 10% dipastikan memiliki sebaran ukuran tersebut.

scholarly journals Efficiency of cloud condensation nuclei formation from ultrafine particles

2007 ◽  
Vol 7 (5) ◽  
pp. 1367-1379 ◽  
Author(s):  
J. R. Pierce ◽  
P. J. Adams
Keyword(s):  
Size Distribution ◽  
Ultrafine Particles ◽  
Particle Deposition ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Ultrafine Particle ◽  
Aerosol Size Distribution ◽  
Condensation Nuclei ◽  
Anthropogenic Aerosol ◽  
Different Parts

Abstract. Atmospheric cloud condensation nuclei (CCN) concentrations are a key uncertainty in the assessment of the effect of anthropogenic aerosol 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. The inputs to the PUG model are the concentrations of condensable gases, the size distribution of ambient aerosol, particle deposition timescales and physical properties of the particles and condensable gases. 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 1% 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 emissions size distribution is generally required for global aerosol microphysics models.

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