scholarly journals Distribution Characteristics of Aerosol Size and CCN during the Summer on Mt. Tian and Their Influencing Factors

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 912
Author(s):  
Ankang Liu ◽  
Honglei Wang ◽  
Yuanyuan Li ◽  
Yan Yin ◽  
Bin Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Influencing Factors ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
Distribution Characteristics ◽  
Condensation Nuclei ◽  
High Supersaturation ◽  
Aerosol Number Concentration ◽  
The Mean

The aerosol size distribution and cloud condensation nuclei (CCN) number concentration were measured using a wide-range particle spectrometer (WPS) and a cloud condensation nuclei counter (CCNC) on Mt. Tian from 31 July to 9 September, 2019. Combined with meteorological data, distribution characteristics of aerosol size and CCN and their influencing factors were analyzed. The results indicated that the mean aerosol number concentration was 5475.6 ± 5636.5 cm−3. The mean CCN concentrations were 183.7 ± 114.5 cm−3, 729.8 ± 376.1 cm−3, 1630.5 ± 980.5 cm−3, 2162.5 ± 1345.3 cm−3, and 2575.7 ± 1632.9 cm−3 at supersaturation levels of 0.1%, 0.2%, 0.4%, 0.6%, and 0.8%, respectively. The aerosol number size distribution is unimodal, and the dominant particle size is 30–60 nm. Affected by the height of the boundary layer and the valley wind, the diurnal variation in aerosol number concentration shows a unimodal distribution with a peak at 17:00, and the CCN number concentration showed a bimodal distribution with peaks at 18:00 and 21:00. The particle size distribution and supersaturation have a major impact on the activation of the aerosol into CCN. At 0.1% supersaturation (S), the 300–500 nm particles are most likely to activate to CCN. Particles of 100–300 nm are most easily activated at 0.2% (S), while particles of 60–80 nm are most likely activated at high supersaturation (≥0.4%). The concentrations of aerosol and CCN are higher in the northerly wind. Ambient relative humidity (RH) has little relationship with the aerosol activation under high supersaturation. According to N = CSk fitting the CCN spectrum, C = 3297 and k = 0.90 on Mt. Tian, characteristic of the clean continental type.

scholarly journals Nucleation-mode particle pool and large increases in <i>N</i><sub>cn</sub> and <i>N</i><sub>ccn</sub> observed over the northwestern Pacific Ocean in the spring of 2014

2019 ◽  
Vol 19 (13) ◽  
pp. 8845-8861 ◽  
Author(s):  
Juntao Wang ◽  
Yanjie Shen ◽  
Kai Li ◽  
Yang Gao ◽  
Huiwang Gao ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
Atmospheric Particles ◽  
Northwestern Pacific ◽  
Condensation Nuclei ◽  
Northwestern Pacific Ocean ◽  
Mean Values ◽  
Nucleation Mode

Abstract. Determination of the updated concentrations of atmospheric particles (Ncn) and the concentrations of cloud condensation nuclei (Nccn) over the northwestern Pacific Ocean (NWPO) are important to accurately evaluate the influence of aerosol outflow from the Asian continent on the climate by considering the rapid changes in emissions of air pollutants therein. However, field observations in the last two decades are scarce. We conducted a cruise campaign over the NWPO to simultaneously measure Ncn, Nccn and the size distribution of aerosol particles from day of year (DOY) 81 to DOY 108 of 2014. The mean values of Nccn at supersaturation (SS) of levels 0.2 % and 0.4 % were 0.68±0.38×103 and 1.1±0.67×103 cm−3, respectively, with an average of 2.8±1.0×103 cm−3 for Ncn during the cruise over the NWPO. All are approximately 1 order of magnitude larger than spring observations made during the preceding two decades in the remote marine atmosphere. The larger values, against the marine natural background reported in the literature, imply an overwhelming contribution from continental inputs. The calculated activity ratios (ARs) of the cloud condensation nuclei (CCN) were 0.30±0.11 and 0.46±0.19 at SS levels of 0.2 % and 0.4 %, respectively, which are almost the same as those of upwind semi-urban sites. High Nccn and CCN activities were observed from DOY 98 to DOY 102, when the oceanic zone received even stronger continental input. Excluding biomass burning (BB) and dust aerosols, good correlation between Nccn at 0.4 % SS and the number concentrations of > 60 nm particles (N>60 nm) was obtained during the entire cruise period, with a slope of 0.98 and R2=0.94, and the corresponding effective hygroscopicity parameter (κ) was estimated to be 0.40. A bimodal size distribution pattern of the particle number concentration was generally observed during the entire campaign when the N>90 nm varied largely. However, the N<30 nm, accounting for approximately one-third of the total number concentration, varied narrowly, and two NPF events associated with vertical transport were observed. This implies that a pool of nucleation-mode atmospheric particles is aloft. BB and dust events were observed over the NWPO, but their aerosol contributions to Ncn and Nccn were minor (i.e., 10 % or less) on a monthly timescale.

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 Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 1: Aerosol size distribution, hygroscopicity, and new model parametrizations for CCN prediction

2016 ◽  
Vol 16 (24) ◽  
pp. 15709-15740 ◽  
Author(s):  
Mira L. Pöhlker ◽  
Christopher Pöhlker ◽  
Florian Ditas ◽  
Thomas Klimach ◽  
Isabella Hrabe de Angelis ◽  
...  
Keyword(s):  
Size Distribution ◽  
Aerosol Particle ◽  
Rain Forest ◽  
Seasonal Cycle ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
Condensation Nuclei ◽  
Central Amazon

Abstract. Size-resolved long-term measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a 1-year period and full seasonal cycle (March 2014–February 2015). The measurements provide a climatology of CCN properties characteristic of a remote central Amazonian rain forest site.The CCN measurements were continuously cycled through 10 levels of supersaturation (S  =  0.11 to 1.10 %) and span the aerosol particle size range from 20 to 245 nm. The mean critical diameters of CCN activation range from 43 nm at S  =  1.10 % to 172 nm at S  =  0.11 %. The particle hygroscopicity exhibits a pronounced size dependence with lower values for the Aitken mode (κAit  =  0.14 ± 0.03), higher values for the accumulation mode (κAcc  =  0.22 ± 0.05), and an overall mean value of κmean  =  0.17 ± 0.06, consistent with high fractions of organic aerosol.The hygroscopicity parameter, κ, exhibits remarkably little temporal variability: no pronounced diurnal cycles, only weak seasonal trends, and few short-term variations during long-range transport events. In contrast, the CCN number concentrations exhibit a pronounced seasonal cycle, tracking the pollution-related seasonality in total aerosol concentration. We find that the variability in the CCN concentrations in the central Amazon is mostly driven by aerosol particle number concentration and size distribution, while variations in aerosol hygroscopicity and chemical composition matter only during a few episodes.For modeling purposes, we compare different approaches of predicting CCN number concentration and present a novel parametrization, which allows accurate CCN predictions based on a small set of input data.

scholarly journals A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

2015 ◽  
Vol 15 (21) ◽  
pp. 12211-12229 ◽  
Author(s):  
M. Paramonov ◽  
V.-M. Kerminen ◽  
M. Gysel ◽  
P. P. Aalto ◽  
M. O. Andreae ◽  
...  
Keyword(s):  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
West Germany ◽  
Aerosol Size Distribution ◽  
Spatial And Temporal Variability ◽  
Condensation Nuclei ◽  
Aerosol Cloud ◽  
Hygroscopic Properties ◽  
South West

Abstract. Cloud condensation nuclei counter (CCNC) measurements performed at 14 locations around the world within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) framework have been analysed and discussed with respect to the cloud condensation nuclei (CCN) activation and hygroscopic properties of the atmospheric aerosol. The annual mean ratio of activated cloud condensation nuclei (NCCN) to the total number concentration of particles (NCN), known as the activated fraction A, shows a similar functional dependence on supersaturation S at many locations – exceptions to this being certain marine locations, a free troposphere site and background sites in south-west Germany and northern Finland. The use of total number concentration of particles above 50 and 100 nm diameter when calculating the activated fractions (A50 and A100, respectively) renders a much more stable dependence of A on S; A50 and A100 also reveal the effect of the size distribution on CCN activation. With respect to chemical composition, it was found that the hygroscopicity of aerosol particles as a function of size differs among locations. The hygroscopicity parameter κ decreased with an increasing size at a continental site in south-west Germany and fluctuated without any particular size dependence across the observed size range in the remote tropical North Atlantic and rural central Hungary. At all other locations κ increased with size. In fact, in Hyytiälä, Vavihill, Jungfraujoch and Pallas the difference in hygroscopicity between Aitken and accumulation mode aerosol was statistically significant at the 5 % significance level. In a boreal environment the assumption of a size-independent κ can lead to a potentially substantial overestimation of NCCN at S levels above 0.6 %. The same is true for other locations where κ was found to increase with size. While detailed information about aerosol hygroscopicity can significantly improve the prediction of NCCN, total aerosol number concentration and aerosol size distribution remain more important parameters. The seasonal and diurnal patterns of CCN activation and hygroscopic properties vary among three long-term locations, highlighting the spatial and temporal variability of potential aerosol–cloud interactions in various environments.

scholarly journals Estimating cloud condensation nuclei concentrations from CALIPSO lidar measurements

2021 ◽  
Author(s):  
Goutam Choudhury ◽  
Matthias Tesche
Keyword(s):  
Size Distribution ◽  
Extinction Coefficient ◽  
Cloud Condensation Nuclei ◽  
Size Distributions ◽  
Marine Aerosols ◽  
Condensation Nuclei ◽  
Aerosol Model ◽  
Initial Application ◽  
Lidar Measurements ◽  
Aerosol Number Concentration

Abstract. We present a novel methodology to estimate cloud condensation nuclei (CCN) concentrations from spaceborne CALIPSO lidar measurements. The algorithm utilizes (i) the CALIPSO-derived backscatter and extinction coefficient, depolarization ratio, and aerosol subtype information, (ii) the normalized volume size distributions and refractive indices from the CALIPSO aerosol model, and (iii) the MOPSMAP optical modelling package. For each CALIPSO height bin, we first select the aerosol-type specific size distribution and then adjust it to reproduce the extinction coefficient derived from the CALIPSO retrieval. The scaled size distribution is integrated to estimate the aerosol number concentration which is then used in the CCN parameterizations to calculate CCN concentrations at different supersaturations. To account for the hygroscopicity of continental and marine aerosols, we use the kappa parameterization and correct the size distributions before the scaling step. We have studied the sensitivity of the thus derived CCN concentration to the effect of variations of the initial size distributions. It is found that the uncertainty associated with the algorithm can range between a factor of 2 and 3. We have also compared our results with the POLIPHON and found comparable results for extinction coefficients larger than 0.05 km−1. An initial application to a case with coincident airborne in-situ measurements for independent validation shows promising results and illustrates the potential of CALIPSO for constructing a global height-resolved CCN climatology.

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 Regional scale effects of the aerosol cloud interaction simulated with an online coupled comprehensive chemistry model

2011 ◽  
Vol 11 (9) ◽  
pp. 4411-4423 ◽  
Author(s):  
M. Bangert ◽  
C. Kottmeier ◽  
B. Vogel ◽  
H. Vogel
Keyword(s):  
Cloud Condensation Nuclei ◽  
Regional Scale ◽  
Cloud Droplet ◽  
Cloud Microphysics ◽  
Model System ◽  
Number Concentration ◽  
Condensation Nuclei ◽  
Close Link ◽  
Cloud Droplet Number Concentration ◽  
The Mean

Abstract. We have extended the coupled mesoscale atmosphere and chemistry model COSMO-ART to account for the transformation of aerosol particles into cloud condensation nuclei and to quantify their interaction with warm cloud microphysics on the regional scale. The new model system aims to fill the gap between cloud resolving models and global scale models. It represents the very complex microscale aerosol and cloud physics as detailed as possible, whereas the continental domain size and efficient codes will allow for both studying weather and regional climate. The model system is applied in a first extended case study for Europe for a cloudy five day period in August 2005. The model results show that the mean cloud droplet number concentration of clouds is correlated with the structure of the terrain, and we present a terrain slope parameter TS to classify this dependency. We propose to use this relationship to parameterize the probability density function, PDF, of subgrid-scale cloud updraft velocity in the activation parameterizations of climate models. The simulations show that the presence of cloud condensation nuclei (CCN) and clouds are closely related spatially. We find high aerosol and CCN number concentrations in the vicinity of clouds at high altitudes. The nucleation of secondary particles is enhanced above the clouds. This is caused by an efficient formation of gaseous aerosol precursors above the cloud due to more available radiation, transport of gases in clean air above the cloud, and humid conditions. Therefore the treatment of complex photochemistry is crucial in atmospheric models to simulate the distribution of CCN. The mean cloud droplet number concentration and droplet diameter showed a close link to the change in the aerosol. To quantify the net impact of an aerosol change on the precipitation we calculated the precipitation susceptibility β for the whole model domain over a period of two days with an hourly resolution. The distribution function of β is slightly skewed to positive values and has a mean of 0.23. Clouds with a liquid water path LWP of approximately 0.85 kg m−2 are on average most susceptible to aerosol changes in our simulations with an absolute value of β of 1. The average β for LWP between 0.5 kg m−2 and 1 kg m−2 is approximately 0.4.

scholarly journals Influence of the dry aerosol particle size distribution and morphology on the cloud condensation nuclei activation. An experimental and theoretical investigation

2020 ◽  
Vol 20 (7) ◽  
pp. 4209-4225 ◽  
Author(s):  
Junteng Wu ◽  
Alessandro Faccinetto ◽  
Symphorien Grimonprez ◽  
Sébastien Batut ◽  
Jérôme Yon ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Spherical Particles ◽  
Equivalent Diameter ◽  
Electrical Mobility ◽  
Condensation Nuclei ◽  
Kohler Theory ◽  
Aerosol Particle Size

Abstract. Combustion and other high-temperature processes frequently result in the emission of aerosols in the form of polydisperse fractal-like aggregates made of condensed-phase nanoparticles (soot for instance). If certain conditions are met, the emitted aerosol particles are known to evolve into important cloud condensation nuclei (CCN) in the atmosphere. In this work, the hygroscopic parameter κ of complex morphology aggregates is calculated from the supersaturation-dependent activated fraction Fa=Fa(SS) in the frame of κ-Köhler theory. The particle size distribution is approximated with the morphology-corrected volume equivalent diameter calculated from the electrical mobility diameter by taking into account the diameter of the primary particle and the fractal dimension of the aggregate experimentally obtained from transmission electron microscopy measurements. Activation experiments are performed in water supersaturation conditions using a commercial CCN-100 condensation nuclei counter. The model is tested in close-to-ideal conditions of size-selected, isolated spherical particles (ammonium sulfate nanoparticles dispersed in nitrogen), then with complex polydisperse fractal-like aggregates (soot particles activated by exposure to ozone with κ as low as 5×10-5) that represent realistic anthropogenic emissions in the atmosphere.

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