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Sonia M. Kreidenweis - One of the best experts on this subject based on the ideXlab platform.
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References
2013Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:aerosol-water interactions A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 2: Including solubility M. D. Petters and S. M. Kreidenwei
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A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 3: Including surfactant partitioning
Atmospheric Chemistry and Physics, 2013Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:Abstract. Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Kohler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code.
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A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 3: Including surfactant partitioning
Copernicus Publications, 2013Co-Authors: Sonia M. Kreidenweis, Markus D. PettersAbstract:Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code
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a single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity part 3 including surfactant partitioning
Atmospheric Chemistry and Physics, 2012Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:Abstract. Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Kohler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code.
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A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 3: Including surfactant partitioning
Atmospheric Chemistry and Physics Discussions, 2012Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:Abstract. Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates the analytical approximations introduced by Raatikainen and Laaksonen to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code. We apply this extended model to discuss several uncertainties that hinder our ability to precisely pinpoint the role of surface tension in Cloud droplet activation with current measurement and data analysis approaches.
Markus D. Petters - One of the best experts on this subject based on the ideXlab platform.
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influence of functional groups on organic aerosol Cloud Condensation Nucleus activity
Environmental Science & Technology, 2014Co-Authors: Sarah R Suda, Markus D. Petters, Geoffrey K Yeh, Christen Strollo, Aiko Matsunaga, Annelise Faulhaber, P Ziemann, Anthony J Prenni, Christian M Carrico, Ryan C SullivanAbstract:Organic aerosols in the atmosphere are composed of a wide variety of species, reflecting the multitude of sources and growth processes of these particles. Especially challenging is predicting how these particles act as Cloud Condensation nuclei (CCN). Previous studies have characterized the CCN efficiency for organic compounds in terms of a hygroscopicity parameter, κ. Here we extend these studies by systematically testing the influence of the number and location of molecular functional groups on the hygroscopicity of organic aerosols. Organic compounds synthesized via gas-phase and liquid-phase reactions were characterized by high-performance liquid chromatography coupled with scanning flow CCN analysis and thermal desorption particle beam mass spectrometry. These experiments quantified changes in κ with the addition of one or more functional groups to otherwise similar molecules. The increase in κ per group decreased in the following order: hydroxyl ≫ carboxyl > hydroperoxide > nitrate ≫ methylene (where nitrate and methylene produced negative effects, and hydroperoxide and nitrate groups produced the smallest absolute effects). Our results contribute to a mechanistic understanding of chemical aging and will help guide input and parametrization choices in models relying on simplified treatments such as the atomic oxygen:carbon ratio to predict the evolution of organic aerosol hygroscopicity.
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References
2013Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:aerosol-water interactions A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 2: Including solubility M. D. Petters and S. M. Kreidenwei
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A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 3: Including surfactant partitioning
Atmospheric Chemistry and Physics, 2013Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:Abstract. Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Kohler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code.
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A single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity – Part 3: Including surfactant partitioning
Copernicus Publications, 2013Co-Authors: Sonia M. Kreidenweis, Markus D. PettersAbstract:Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code
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a single parameter representation of hygroscopic growth and Cloud Condensation Nucleus activity part 3 including surfactant partitioning
Atmospheric Chemistry and Physics, 2012Co-Authors: Markus D. Petters, Sonia M. KreidenweisAbstract:Abstract. Atmospheric particles can serve as Cloud Condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Kohler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of Cloud Condensation Nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code.
Dean A. Hegg - One of the best experts on this subject based on the ideXlab platform.
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Aerosol number-to-volume relationship and relative humidity in the eastern Atlantic
Journal of Geophysical Research: Atmospheres, 2000Co-Authors: Dean A. Hegg, Haflidi H. JonssonAbstract:Measurements acquired from the Office of Naval Research (ONR) Pelican research aircraft during the second Aerosol Characterization Experiment (ACE 2) are analyzed to derive values for the dry (RH = 40%) aerosol number-to-volume ratio in the submicron size range. This ratio is found to be relatively constant, with a mean value of 168±21 μm−3, in agreement with previous studies elsewhere. The impact of ambient relative humidity (RH) on the dry number-to-volume is also quantified and a procedure for estimating the dry from the ambient ratio established. Finally, the feasibility of a remote retrieval of the aerosol number concentration in the submicron size range, essentially the Cloud Condensation Nucleus concentration active at a nominal 0.2% supersaturation, is partially assessed.
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Aerosol number-to-volume relationship humidity in the eastern Atlantic
2000Co-Authors: Dean A. Hegg, Hafiidi JonssonAbstract:Measurements acquired from the Office of Naval Research (ONR) Pelican research aircraft during the second Aerosol Characterization Experiment (ACE 2) are analyzed to derive values for the dry (RH = 40%) aerosol number-to-volume ratio in the submicron size range. This ratio is found to be relatively constant, with a mean value of 168 _+ 21 gm -3, in agreement with previous studies elsewhere. The impact of ambient relative humidity (RH) on the dry number-to-volume is also quantified and a procedure for estimating the dry from the ambient ratio established. Finally, the feasibility of a remote retrieval of the aerosol number concentration in the submicron size range, essentially the Cloud Condensation Nucleus concentration active at a nominal 0.2% supersaturation, is partially assessed.
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Measurements of ship‐induced tracks in Clouds off the Washington coast
Journal of Geophysical Research: Atmospheres, 1998Co-Authors: Ronald J. Ferek, Dean A. Hegg, Peter V. Hobbs, Philip A. Durkee, K. NielsenAbstract:In situ Cloud microphysical measurements are presented for two ship tracks detected off the Washington coast in three successive satellite images from the advanced very high resolution radiometer (AVHRR) channel 3 (3.7 μm). Aerosol and Cloud water chemical data suggest that the tracks were produced by effluents from ship stacks. Cloud droplet spectra measured in the ship tracks had effective radii about one half of those measured in the ambient Clouds. A drizzle mode was present in the ambient Cloud, but this was largely suppressed in the ship tracks. Analysis of Cloud Condensation Nucleus (CCN) and total particle spectra in and around the ship tracks suggest that the stability of the tracks could have been due to a feedback between the lowering of CCN concentrations as the ship plumes diluted, consequent increases in peak supersaturations in the Cloud, and a modest amount of particle growth by gas-to-particle conversion.
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Aerosol measurements in the Arctic relevant to direct and indirect radiative forcing
Journal of Geophysical Research: Atmospheres, 1996Co-Authors: Dean A. Hegg, Peter V. Hobbs, Santiago Gassó, Jon D. Nance, Arthur L. RangnoAbstract:Airborne measurements in the Arctic in June permit calculation of some of the parameters needed to assess both the direct and indirect radiative forcing by aerosols in the region. Values for the single-scattering albedo of the aerosols suggest that in June the direct effect will produce a net cooling, in contrast to winter arctic hazes. Internal closure calculations comparing aerosol size distribution measurements with directly measured light scattering by aerosols over the first 4 km of the atmosphere show good agreement. Measurements of Cloud Condensation Nucleus (CCN) activation spectra show steeper slopes than previous measurements in the Arctic in winter and early spring. Based on the CCN and collated Cloud microphysical measurements, the susceptibility of the Clouds encountered in this project to aerosol-induced albedo modification appears quite high.
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Cloud Condensation nuclei over the Arctic Ocean in early spring
Journal of Applied Meteorology, 1995Co-Authors: Dean A. Hegg, Ronald J. Ferek, Peter V. HobbsAbstract:Abstract Cloud Condensation Nucleus (CCN) spectral data are presented for the Arctic in spring, which considerably augment the existing meager CCN database for the Arctic. Concurrent measurements of sulfate mass suggest that men of the CCN were commonly not sulfate. Sulfate was more closely associated with particles below the CCN size range. Some measurements of the microphysical structure of Arctic status Clouds are aim described.
John H. Seinfeld - One of the best experts on this subject based on the ideXlab platform.
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On the Link Between Ocean Biota Emissions, Aerosol, and Maritime Clouds: Airborne, Ground, and Satellite Measurements off the Coast of
2015Co-Authors: Scott P. Hersey, Richard C. Flagan, Haflidi H. Jonsson, Harmony Gates, Steven D, Graeme L. Stephens, John H. SeinfeldAbstract:1 Surface, airborne, and satellite measurements over the eastern Pacific Ocean off the coast of California during the period between 2005 and 2007 are used to explore the relationship between ocean chlorophyll A, aerosol, and marine Clouds. Periods of enhanced chlorophyll A and wind speed are coincident with increases in particulate diethylamine and methanesulfonate concentrations. The measurements indicate that amines are a source of secondary organic aerosol in the marine atmosphere. Subsaturated aerosol hygroscopic growth measurements indicate that the organic component during periods of high chlorophyll A and wind speed exhibit considerable water-uptake ability. Increased average Cloud Condensation Nucleus (CCN) activity during periods of increased chlorophyll A levels likely results from both size distribution and aerosol composition changes. The available data over the period of measurements indicate that the clou
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1Concept for a New Cloud Condensation Nucleus (CCN) Spectrometer
2015Co-Authors: Timothy M. Vanreken, Athanasios Nenes, Richard C. Flagan, John H. SeinfeldAbstract:The design of a new Cloud Condensation Nucleus (CCN) spectrometer based on modifications to the original design of Fukuta and Saxena (1979a) is presented. The key modifications include introducing a trapezoidal geometry and orienting the chamber vertically. A series of simulations demonstrate the broadening of the effective range of the instrument to include supersaturations lower than those reported for the original instrument, without reducing the maximum resolvable supersaturation. A design criterion is developed to eliminate configurations that would result in secondary flows in the growth chamber resulting from buoyancy effects. Using instrument configurations that satisfy this criterion, the effects of variations in the chamber geometry, the imposed temperature gradient, and the total volumetric flow are evaluated. A new configuration is identified that could produce real-time CCN spectra with an effective range including at least supersaturations between 0.07 % and 1.2%. 3INTRODUCTION In order to improve our understanding of the role of aerosols in Cloud development and propagation, it is necessary to measure the Cloud-forming ability of the aeroso
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Cloud Condensation Nucleus (CCN) behavior of organic aerosol particles generated by atomization of water and methanol solutions
Atmospheric Chemistry and Physics, 2007Co-Authors: T. A. Rissman, Richard C. Flagan, V. Varutbangkul, J. D. Surratt, D. O. Topping, G. Mcfiggans, John H. SeinfeldAbstract:Cloud Condensation Nucleus (CCN) experiments were carried out for malonic acid, succinic acid, oxalacetic acid, DL-malic acid, glutaric acid, DL-glutamic acid monohydrate, and adipic acid, using both water and methanol as atomization solvents, at three operating supersaturations (0.11%, 0.21%, and 0.32%) in the Caltech three-column CCN instrument (CCNC3). Predictions of CCN behavior for five of these compounds were made using the Aerosol Diameter Dependent Equilibrium Model (ADDEM). The experiments presented here expose important considerations associated with the laboratory measurement of the CCN behavior of organic compounds. Choice of atomization solvent results in significant differences in CCN activation for some of the compounds studied, which could result from residual solvent, particle morphology differences, and chemical reactions between the particle and gas phases. Also, significant changes in aerosol size distribution occurred after classification in a differential mobility analyzer (DMA) for malonic acid and glutaric acid, preventing confident interpretation of experimental data for these two compounds. Filter analysis of adipic acid atomized from methanol solution indicates that gas-particle phase reactions may have taken place after atomization and before methanol was removed from the sample gas stream. Careful consideration of these experimental issues is necessary for successful design and interpretation of laboratory CCN measurements.
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Cloud Condensation Nucleus (CCN) behavior of organic aerosol particles generated by atomization of water and methanol solutions
Atmospheric Chemistry and Physics Discussions, 2006Co-Authors: T. A. Rissman, Richard C. Flagan, V. Varutbangkul, J. D. Surratt, D. O. Topping, G. Mcfiggans, John H. SeinfeldAbstract:Cloud Condensation Nucleus (CCN) experiments were carried out for malonic acid, succinic acid, oxalacetic acid, DL-malic acid, glutaric acid, DL-glutamic acid monohydrate, and adipic acid, using both water and methanol as atomization solvents, at three operating supersaturations (0.11% 0.21%, and 0.32%) in the Caltech three-column CCN instrument (CCNC3). Predictions of CCN behavior for five of these compounds were made using the Aerosol Diameter Dependent Equilibrium Model (ADDEM). The experiments presented here expose important considerations associated with the laboratory measurement of the CCN behavior of organic compounds. Choice of atomization solvent results in significant differences in CCN activation for some of the compounds studied, which could result from residual solvent, particle morphology differences, and chemical reactions between the particle and gas phases. Also, significant changes in aerosol size distribution occurred after classification in a differential mobility analyzer (DMA) for malonic acid and glutaric acid. Filter analysis of adipic acid atomized from methanol solution indicates that gas-particle phase reactions may have taken place after atomization and before the methanol was removed from the sample gas stream. Careful consideration of these experimental issues is necessary for successful design and interpretation of laboratory CCN measurements.
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Cloud Condensation Nucleus activation properties of biogenic secondary organic aerosol
Journal of Geophysical Research, 2005Co-Authors: Timothy M. Vanreken, Richard C. Flagan, John H. SeinfeldAbstract:monoterpenes (a-pinene, b-pinene, limonene, and D 3 -carene) and one terpenoid alcohol (terpinene-4-ol). In each case the aerosol formation was driven by the reaction of ozone with the biogenic precursor. The SOA produced in each experiment was allowed to age for several hours, during which CCN concentrations were periodically measured at four supersaturations: S = 0.27%, 0.32%, 0.54%, and 0.80%. The calculated relationships between particle dry diameter and critical supersaturation were found to fall in the range of previously reported data for single-component organic aerosols; of the systems studied, a-pinene SOA was the least CCN active, while limonene SOA exhibited the strongest CCN activity. Interestingly, the inferred critical supersaturation of the SOA products was considerably more sensitive to particle diameter than was found in previous studies. Furthermore, the relationships between particle size and critical supersaturation for the monoterpene SOA shifted considerably over the course of the experiments, with the aerosol becoming less hygroscopic over time. These results are consistent with the progressive oligomerization of the SOA.
Peter V. Hobbs - One of the best experts on this subject based on the ideXlab platform.
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Cloud Condensation nuclei and ship tracks
Journal of the Atmospheric Sciences, 2000Co-Authors: James G. Hudson, Peter V. Hobbs, Timothy J. Garrett, Scott R. Strader, Yonghong Xie, Seong Soo YumAbstract:Enhancements of droplet concentrations in Clouds affected by four ships were fairly accurately predicted from ship emission factors and plume and background Cloud Condensation Nucleus (CCN) spectra. Ship exhausts thus accounted for the increased droplet concentrations in these ‘‘ship tracks.’’ Derived supersaturations were typical of marine stratus Clouds, although there was evidence of some lowering of supersaturations in some ship tracks closer to the ships where CCN and droplet concentrations were very high. Systematic differences were measured in the emission rates of CCN for different engines and fuels. Diesel engines burning low-grade marine fuel oil produced order of magnitude higher CCN emissions than turbine engines burning higher-grade fuel. Consequently, diesel ships burning low-grade fuel were responsible for nearly all of the observed ship track Clouds. There is some evidence that fuel type is a better predictor of ship track potential than engine type.
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Measurements of ship‐induced tracks in Clouds off the Washington coast
Journal of Geophysical Research: Atmospheres, 1998Co-Authors: Ronald J. Ferek, Dean A. Hegg, Peter V. Hobbs, Philip A. Durkee, K. NielsenAbstract:In situ Cloud microphysical measurements are presented for two ship tracks detected off the Washington coast in three successive satellite images from the advanced very high resolution radiometer (AVHRR) channel 3 (3.7 μm). Aerosol and Cloud water chemical data suggest that the tracks were produced by effluents from ship stacks. Cloud droplet spectra measured in the ship tracks had effective radii about one half of those measured in the ambient Clouds. A drizzle mode was present in the ambient Cloud, but this was largely suppressed in the ship tracks. Analysis of Cloud Condensation Nucleus (CCN) and total particle spectra in and around the ship tracks suggest that the stability of the tracks could have been due to a feedback between the lowering of CCN concentrations as the ship plumes diluted, consequent increases in peak supersaturations in the Cloud, and a modest amount of particle growth by gas-to-particle conversion.
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Aerosol measurements in the Arctic relevant to direct and indirect radiative forcing
Journal of Geophysical Research: Atmospheres, 1996Co-Authors: Dean A. Hegg, Peter V. Hobbs, Santiago Gassó, Jon D. Nance, Arthur L. RangnoAbstract:Airborne measurements in the Arctic in June permit calculation of some of the parameters needed to assess both the direct and indirect radiative forcing by aerosols in the region. Values for the single-scattering albedo of the aerosols suggest that in June the direct effect will produce a net cooling, in contrast to winter arctic hazes. Internal closure calculations comparing aerosol size distribution measurements with directly measured light scattering by aerosols over the first 4 km of the atmosphere show good agreement. Measurements of Cloud Condensation Nucleus (CCN) activation spectra show steeper slopes than previous measurements in the Arctic in winter and early spring. Based on the CCN and collated Cloud microphysical measurements, the susceptibility of the Clouds encountered in this project to aerosol-induced albedo modification appears quite high.
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Cloud Condensation nuclei over the Arctic Ocean in early spring
Journal of Applied Meteorology, 1995Co-Authors: Dean A. Hegg, Ronald J. Ferek, Peter V. HobbsAbstract:Abstract Cloud Condensation Nucleus (CCN) spectral data are presented for the Arctic in spring, which considerably augment the existing meager CCN database for the Arctic. Concurrent measurements of sulfate mass suggest that men of the CCN were commonly not sulfate. Sulfate was more closely associated with particles below the CCN size range. Some measurements of the microphysical structure of Arctic status Clouds are aim described.
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Reassessing the dependence of Cloud Condensation Nucleus concentration on formation rate
Nature, 1994Co-Authors: Andrew S. Ackerman, Owen B. Toon, Peter V. HobbsAbstract:MARINE stratocumulus Clouds play an important role in the Earth's radiation budget. The albedo of these Clouds depends on the Cloud droplet size distribution, and therefore, in part, on the number density of Cloud Condensation nuclei (CCN)1. It has been postulated2 that a positive feedback loop between increased CCN concentrations and decreased drizzle gives rise to a bistable system, in which there are two equilibrium CCN concentration regimes. According to this model, CCN concentration is only weakly dependent on the CCN production rate within the stable regimes, but very strongly dependent on this rate in the transition region between the regimes. If correct, this strong dependence implies that a small increase in the production of CCN over the oceans could drastically increase the planetary albedo. Using a more sophisticated model3 than that used previously, we find no evidence for bistability. However, we find that CCN concentrations are generally strongly dependent on their production rate, so that changes in the latter would influence the Earth's albedo. We also find that the timescale for reducing high CCN concentrations can be as long as several days, which implies that high CCN concentrations can persist in Clouds advected to regions of lower CCN production rate.