scholarly journals Simultaneous Measurements of Hygroscopic Property and Cloud Condensation Nucleus Activity of Aerosol Particles of Marine Biogenic Origin

2014 ◽  
pp. 71-81 ◽  
Author(s):  
M. Mochida
Keyword(s):  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Biogenic Origin ◽  
Hygroscopic Property ◽  
Simultaneous Measurements

Hygroscopicity and cloud condensation nucleus activity of marine aerosol particles over the western North Pacific

2011 ◽  
Vol 116 (D6) ◽  
Author(s):  
Michihiro Mochida ◽  
Chiharu Nishita-Hara ◽  
Hiroshi Furutani ◽  
Yuzo Miyazaki ◽  
Jinyoung Jung ◽  
...  
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Marine Aerosol

scholarly journals Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements

2011 ◽  
Vol 4 (1) ◽  
pp. 691-713 ◽  
Author(s):  
N. Hiranuma ◽  
M. Kohn ◽  
M. S. Pekour ◽  
D. A. Nelson ◽  
J. E. Shilling ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Droplet Size ◽  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Polystyrene Latex ◽  
Cloud Condensation Nucleus ◽  
Particle Analysis ◽  
Laser Mass Spectrometry ◽  
Atmospheric Measurements ◽  
Virtual Impactor

Abstract. Droplets produced in a cloud condensation nucleus chamber as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer and the Particle Analysis by Laser Mass Spectrometry instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (ammonium sulfate) but not the other (polystyrene latex spheres). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from atmospheric measurements using this technique indicate that aerosol particles often activate predominantly as a function of particle size. Chemical composition is not irrelevant, however, and we observed enhancement of sulfate in droplet residuals using single particle analysis.

scholarly journals Ammonium nitrate evaporation and nitric acid condensation in DMT CCN counters

2014 ◽  
Vol 7 (5) ◽  
pp. 1377-1384 ◽  
Author(s):  
S. Romakkaniemi ◽  
A. Jaatinen ◽  
A. Laaksonen ◽  
A. Nenes ◽  
T. Raatikainen
Keyword(s):  
Nitric Acid ◽  
Ammonium Nitrate ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Ambient Conditions ◽  
Particle Activation ◽  
Maximum Water ◽  
Ccn Activity

Abstract. The effect of inorganic semivolatile aerosol compounds on the cloud condensation nucleus (CCN) activity of aerosol particles was studied by using a computational model for a DMT-CCN counter, a cloud parcel model for condensation kinetics and experiments to quantify the modelled results. Concentrations of water vapour and semivolatiles as well as aerosol trajectories in the CCN column were calculated by a computational fluid dynamics model. These trajectories and vapour concentrations were then used as an input for the cloud parcel model to simulate mass transfer kinetics of water and semivolatiles between aerosol particles and the gas phase. Two different questions were studied: (1) how big a fraction of semivolatiles is evaporated from particles after entering but before particle activation in the DMT-CCN counter? (2) How much can the CCN activity be increased due to condensation of semivolatiles prior to the maximum water supersaturation in the case of high semivolatile concentration in the gas phase? Both experimental and modelling results show that the evaporation of ammonia and nitric acid from ammonium nitrate particles causes a 10 to 15 nm decrease to the critical particle size in supersaturations between 0.1% and 0.7%. On the other hand, the modelling results also show that condensation of nitric acid or similar vapour can increase the CCN activity of nonvolatile aerosol particles, but a very high gas phase concentration (as compared to typical ambient conditions) would be needed. Overall, it is more likely that the CCN activity of semivolatile aerosol is underestimated than overestimated in the measurements conducted in ambient conditions.

scholarly journals A novel model to predict the physical state of atmospheric H<sub>2</sub>SO<sub>4</sub>/NH<sub>3</sub>/H<sub>2</sub>O aerosol particles

2002 ◽  
Vol 2 (6) ◽  
pp. 2449-2487 ◽  
Author(s):  
C. A. Colberg ◽  
B. P. Luo ◽  
H. Wernli ◽  
T. Koop ◽  
Th. Peter
Keyword(s):  
Physical State ◽  
Aerosol Particles ◽  
Circulation Model ◽  
Condensation Nucleus ◽  
Radiative Properties ◽  
Cloud Condensation Nucleus ◽  
Cloud Formation ◽  
Global Circulation Model ◽  
Full Account ◽  
Tropospheric Aerosol

Abstract. The physical state of tropospheric aerosol particles is largely unknown despite its importance for cloud formation and for the aerosols' radiative properties. Here we show the first systematic global modelling study of the physical state of the H2SO4/NH3/H2O aerosol, which constitutes an important class of aerosols in the free troposphere. The Aerosol Physical State Model (APSM) developed here is based on Lagrangian trajectories computed from ECMWF (European Centre for Medium Range Weather Forecasts) analyses, taking full account of the deliquescence/efflorescence hysteresis. As input APSM requires three data sets: (i) deliquescence and efflorescence relative humidities from laboratory measurements, (ii) ammonia-to-sulfate ratios (ASR) calculated by a global circulation model, and (iii) relative humidities determined from the ECMWF analyses. APSM results indicate that globally averaged a significant fraction (17-57%) of the ammoniated sulfate aerosol particles contain solids with the ratio of solid-containing to purely liquid particles increasing with altitude (between 2 and 10 km). In our calculations the most abundant solid is letovicite, (NH4)3H(SO4)2, while there is only little ammonium sulfate, (NH4)2SO4. Since ammonium bisulfate, NH4HSO4, does not nucleate homogeneously, it can only form via heterogeneous crystallization. As the ammonia-to-sulfate ratios of the atmospheric aerosol usually do not correspond to the stoichiometries of known crystalline substances, all solids are expected to occur in mixed-phase aerosol particles. This work highlights the global importance of letovicite, whose role as cloud condensation nucleus (CCN) and as scatterer of solar radiation remains to be scrutinized.

scholarly journals Effects of 20–100 nm particles on liquid clouds in the clean summertime Arctic

2016 ◽  
Vol 16 (17) ◽  
pp. 11107-11124 ◽  
Author(s):  
W. Richard Leaitch ◽  
Alexei Korolev ◽  
Amir A. Aliabadi ◽  
Julia Burkart ◽  
Megan D. Willis ◽  
...  
Keyword(s):  
Liquid Water ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
Positive Association ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
The Arctic ◽  
Low Carbon ◽  
Clean Environment ◽  
Low Altitude

Abstract. Observations addressing effects of aerosol particles on summertime Arctic clouds are limited. An airborne study, carried out during July 2014 from Resolute Bay, Nunavut, Canada, as part of the Canadian NETCARE project, provides a comprehensive in situ look into some effects of aerosol particles on liquid clouds in the clean environment of the Arctic summer. Median cloud droplet number concentrations (CDNC) from 62 cloud samples are 10 cm−3 for low-altitude cloud (clouds topped below 200 m) and 101 cm−3 for higher-altitude cloud (clouds based above 200 m). The lower activation size of aerosol particles is  ≤  50 nm diameter in about 40 % of the cases. Particles as small as 20 nm activated in the higher-altitude clouds consistent with higher supersaturations (S) for those clouds inferred from comparison of the CDNC with cloud condensation nucleus (CCN) measurements. Over 60 % of the low-altitude cloud samples fall into the CCN-limited regime of Mauritsen et al. (2011), within which increases in CDNC may increase liquid water and warm the surface. These first observations of that CCN-limited regime indicate a positive association of the liquid water content (LWC) and CDNC, but no association of either the CDNC or LWC with aerosol variations. Above the Mauritsen limit, where aerosol indirect cooling may result, changes in particles with diameters from 20 to 100 nm exert a relatively strong influence on the CDNC. Within this exceedingly clean environment, as defined by low carbon monoxide and low concentrations of larger particles, the background CDNC are estimated to range between 16 and 160 cm−3, where higher values are due to activation of particles  ≤  50 nm that likely derive from natural sources. These observations offer the first wide-ranging reference for the aerosol cloud albedo effect in the summertime Arctic.

scholarly journals Aerosol- and updraft-limited regimes of cloud droplet formation: influence of particle number, size and hygroscopicity on the activation of cloud condensation nuclei (CCN)

2009 ◽  
Vol 9 (2) ◽  
pp. 8635-8665 ◽  
Author(s):  
P. Reutter ◽  
J. Trentmann ◽  
H. Su ◽  
M. Simmel ◽  
D. Rose ◽  
...  
Keyword(s):  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
Condensation Nucleus ◽  
Droplet Formation ◽  
Cloud Condensation Nucleus ◽  
Aerosol Size Distribution ◽  
Cloud Base ◽  
Wide Range

Abstract. We have investigated the formation of cloud droplets under (pyro-)convective conditions using a cloud parcel model with detailed spectral microphysics and with the κ-Köhler model approach for efficient and realistic description of the cloud condensation nucleus (CCN) activity of aerosol particles. Assuming a typical biomass burning aerosol size distribution (accumulation mode centred at 120 nm), we have calculated initial cloud droplet number concentrations (NCD) for a wide range of updraft velocities (w=0.5–20 m s−1) and aerosol particle number concentrations (NCN=103–105 cm−3) at the cloud base. Depending on the ratio between updraft velocity and particle number concentration (w/NCN), we found three distinctly different regimes of CCN activation and cloud droplet formation: 1. An aerosol-limited regime that is characterized by high w/NCN ratios (>≈10−3 m s−1 cm3), high maximum values of water vapour supersaturation (Smax>≈0.5%), and high activated fractions of aerosol particles (NCD/NCN>≈90%). In this regime NCD is directly proportional to NCN and practically independent of w. 2. An updraft-limited regime that is characterized by low w/NCN ratios (

scholarly journals Aerosol- and updraft-limited regimes of cloud droplet formation: influence of particle number, size and hygroscopicity on the activation of cloud condensation nuclei (CCN)

2009 ◽  
Vol 9 (18) ◽  
pp. 7067-7080 ◽  
Author(s):  
P. Reutter ◽  
H. Su ◽  
J. Trentmann ◽  
M. Simmel ◽  
D. Rose ◽  
...  
Keyword(s):  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Cloud Droplet ◽  
Condensation Nucleus ◽  
Droplet Formation ◽  
Cloud Condensation Nucleus ◽  
Aerosol Size Distribution ◽  
Cloud Base ◽  
Wide Range

Abstract. We have investigated the formation of cloud droplets under pyro-convective conditions using a cloud parcel model with detailed spectral microphysics and with the κ-Köhler model approach for efficient and realistic description of the cloud condensation nucleus (CCN) activity of aerosol particles. Assuming a typical biomass burning aerosol size distribution (accumulation mode centred at 120 nm), we have calculated initial cloud droplet number concentrations (NCD) for a wide range of updraft velocities (w=0.25–20 m s−1) and aerosol particle number concentrations (NCN=200–105 cm−3) at the cloud base. Depending on the ratio between updraft velocity and particle number concentration (w/NCN), we found three distinctly different regimes of CCN activation and cloud droplet formation: (1) An aerosol-limited regime that is characterized by high w/NCN ratios (>≈10−3 m s−1 cm3), high maximum values of water vapour supersaturation (Smax>≈0.5%), and high activated fractions of aerosol particles (NCN/NCN>≈90%). In this regime NCD is directly proportional to NCN and practically independent of w. (2) An updraft-limited regime that is characterized by low w/NCN ratios (

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