Reassessing the dependence of cloud condensation nucleus concentration on formation rate

Nature ◽  
1994 ◽  
Vol 367 (6462) ◽  
pp. 445-447 ◽  
Author(s):  
Andrew S. Ackerman ◽  
Owen B. Toon ◽  
Peter V. Hobbs
Keyword(s):  
Formation Rate ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Nucleus Concentration

scholarly journals Polarimetric Backscatter Sonde Observations of Southern Ocean Clouds and Aerosols

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 399
Author(s):  
Murray Hamilton ◽  
Simon P. Alexander ◽  
Alain Protat ◽  
Steven Siems ◽  
Scott Carpentier
Keyword(s):  
Monte Carlo Model ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Cloud Base ◽  
Back Trajectory ◽  
Cloud Particle ◽  
Macquarie Island ◽  
Back Trajectory Analysis ◽  
Substantial Concentration ◽  
Nucleus Concentration

Balloon-borne polarimetric backscatter sonde (polarsonde) observations of aerosol and cloud during the approach of a cold front at Macquarie Island (54.499 S 158.937 E) are described. The polarsonde captures vertical profiles of cloud occurrence and phase. The cloud base and cloud top heights from the backscatter sonde compare favourably with observations made by a co-located cloud radar and ceilometer. An estimate of the total scatter probability from a liquid cloud layer at 1000 m height is used with a Monte Carlo model of the instrument to obtain cloud particle concentration, and this is compared to a measurement of cloud condensation nucleus concentration made at sea level. Backscatter from aerosol, as well as cloud, is significant. A high aerosol loading in part of the pre-frontal airmass is observed at altitudes up to 6 km. Below the melting level, the high cross-polarised return, relative to the co-polarised, indicates a substantial concentration of solid, non-spherical aerosol particles, which due to the high humidity cannot be sea salt or sulphate. A back trajectory analysis indicates that the observed aerosol includes continental dust.

The effect of atmospheric nitric acid vapor on cloud condensation nucleus activation

1993 ◽  
Vol 98 (D12) ◽  
pp. 22949 ◽  
Author(s):  
M. Kulmala ◽  
A. Laaksonen ◽  
P. Korhonen ◽  
T. Vesala ◽  
T. Ahonen ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Condensation Nucleus ◽  
Cloud Condensation Nucleus ◽  
Acid Vapor

scholarly journals A global process-based study of marine CCN trends and variability

2014 ◽  
Vol 14 (11) ◽  
pp. 15771-15801
Author(s):  
E. M. Dunne ◽  
S. Mikkonen ◽  
H. Kokkola ◽  
H. Korhonen
Keyword(s):  
Wind Speed ◽  
Condensation Nucleus ◽  
Feedback Mechanism ◽  
Radiative Properties ◽  
Climate Feedback ◽  
Cloud Condensation Nucleus ◽  
Aerosol Model ◽  
The North ◽  
Nucleation Scavenging ◽  
Climate Cooling

Abstract. Low-level clouds have a strong climate-cooling effect in oceanic regions due to the much lower albedo of the underlying sea surface. Marine clouds typically have low droplet concentrations, making their radiative properties susceptible to changes in cloud condensation nucleus (CCN) concentrations. Here, we use the global aerosol model GLOMAP to investigate the processes that determine variations in marine CCN concentrations, and focus especially on the effects of previously identified wind speed trends in recent decades. Although earlier studies have found a link between linear wind speed trends and CCN concentration, we find that the effects of wind speed trends identified using a dynamic linear model in the Northern Equatorial Pacific (0.56 m s−1 per decade in the period 1990–2004) and the North Atlantic (−0.21 m s−1 per decade) are largely dampened by other processes controlling the CCN concentration, namely nucleation scavenging and transport of continental pollution. A CCN signal from wind speed change is seen only in the most pristine of the studied regions, i.e. over the Southern Ocean, where we simulate 3.4 cm−3 and 0.17 m s−1 increases over the fifteen-year period in the statistical mean levels of CCN and wind speed, respectively. Our results suggest that future changes in wind-speed-driven aerosol emissions from the oceans can probably have a climate feedback via clouds only in the most pristine regions. On the other hand, a feedback mechanism via changing precipitation patterns and intensities could take place over most oceanic regions, as we have shown that nucleation scavenging has by far the largest absolute effect on CCN concentrations.

scholarly journals A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 2: Including solubility

2008 ◽  
Vol 8 (20) ◽  
pp. 6273-6279 ◽  
Author(s):  
M. D. Petters ◽  
S. M. Kreidenweis
Keyword(s):  
Unit Volume ◽  
Condensation Nucleus ◽  
Single Parameter ◽  
Saturated Solution ◽  
Cloud Condensation Nucleus ◽  
Hygroscopic Growth ◽  
Solubility In Water ◽  
Parameter Representation ◽  
Model Complex ◽  
Ccn Activity

Abstract. The ability of a particle to serve as a cloud condensation nucleus in the atmosphere is determined by its size, hygroscopicity and its solubility in water. Usually size and hygroscopicity alone are sufficient to predict CCN activity. Single parameter representations for hygroscopicity have been shown to successfully model complex, multicomponent particles types. Under the assumption of either complete solubility, or complete insolubility of a component, it is not necessary to explicitly include that component's solubility into the single parameter framework. This is not the case if sparingly soluble materials are present. In this work we explicitly account for solubility by modifying the single parameter equations. We demonstrate that sensitivity to the actual value of solubility emerges only in the regime of 2×10−1–5×10−4, where the solubility values are expressed as volume of solute per unit volume of water present in a saturated solution. Compounds that do not fall inside this sparingly soluble envelope can be adequately modeled assuming they are either infinitely soluble in water or completely insoluble.

scholarly journals A global process-based study of marine CCN trends and variability

2014 ◽  
Vol 14 (24) ◽  
pp. 13631-13642 ◽  
Author(s):  
E. M. Dunne ◽  
S. Mikkonen ◽  
H. Kokkola ◽  
H. Korhonen
Keyword(s):  
Wind Speed ◽  
Condensation Nucleus ◽  
Feedback Mechanism ◽  
Radiative Properties ◽  
Climate Feedback ◽  
Cloud Condensation Nucleus ◽  
Aerosol Model ◽  
The North ◽  
Nucleation Scavenging ◽  
Climate Cooling

Abstract. Low-level clouds have a strong climate-cooling effect in oceanic regions due to the much lower albedo of the underlying sea surface. Marine clouds typically have low droplet concentrations, making their radiative properties susceptible to changes in cloud condensation nucleus (CCN) concentrations. Here, we use the global aerosol model GLOMAP to investigate the processes that determine variations in marine CCN concentrations, and focus especially on the effects of previously identified wind speed trends in recent decades. Although earlier studies have found a link between linear wind speed trends and CCN concentration, we find that the effects of wind speed trends identified using a dynamic linear model in the Northern Equatorial Pacific (0.56 m s−1 per decade in the period 1990–2004) and the North Atlantic (−0.21 m s−1 per decade) are largely dampened by other processes controlling the CCN concentration, namely nucleation scavenging and transport of continental pollution. A CCN signal from wind speed change is seen only in the most pristine of the studied regions, i.e. over the Southern Ocean, where we simulate 3.4 cm−3 and 0.17 m s−1 increases over the 15-year period in the statistical mean levels of CCN and wind speed, respectively. Our results suggest that future changes in wind-speed-driven aerosol emissions from the oceans can probably have a climate feedback via clouds only in the most pristine regions. On the other hand, a feedback mechanism via changing precipitation patterns and intensities could take place over most oceanic regions, as we have shown that nucleation scavenging has by far the largest absolute effect on CCN concentrations.

scholarly journals Hygroscopic properties of Amazonian biomass burning and European background HULIS and investigation of their effects on surface tension with two models linking H-TDMA to CCNC data

2010 ◽  
Vol 10 (12) ◽  
pp. 5625-5639 ◽  
Author(s):  
E. O. Fors ◽  
J. Rissler ◽  
A. Massling ◽  
B. Svenningsson ◽  
M. O. Andreae ◽  
...  
Keyword(s):  
Surface Tension ◽  
Biomass Burning ◽  
Organic Material ◽  
Inorganic Compounds ◽  
Pure Water ◽  
Condensation Nucleus ◽  
Water Soluble ◽  
Cloud Condensation Nucleus ◽  
Rural Site ◽  
Hygroscopic Properties

Abstract. HUmic-LIke Substances (HULIS) have been identified as major contributors to the organic carbon in atmospheric aerosol. The term "HULIS" is used to describe the organic material found in aerosol particles that resembles the humic organic material in rivers and sea water and in soils. In this study, two sets of filter samples from atmospheric aerosols were collected at different sites. One set of samples was collected at the K-puszta rural site in Hungary, about 80 km SE of Budapest, and a second was collected at a site in Rondônia, Amazonia, Brazil, during the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) biomass burning season experiment. HULIS were extracted from the samples and their hygroscopic properties were studied using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA) at relative humidity (RH) <100%, and a cloud condensation nucleus counter (CCNC) at RH >100%. The H-TDMA measurements were carried out at a dry diameter of 100 nm and for RH ranging from 30 to 98%. At 90% RH the HULIS samples showed diameter growth factors between 1.04 and 1.07, reaching values of 1.4 at 98% RH. The cloud nucleating properties of the two sets of aerosol samples were analysed using two types of thermal static cloud condensation nucleus counters. Two different parameterization models were applied to investigate the potential effect of HULIS surface activity, both yielding similar results. For the K-puszta winter HULIS sample, the surface tension at the point of activation was estimated to be lowered by between 34% (47.7 mN/m) and 31% (50.3 mN/m) for dry sizes between 50 and 120 nm in comparison to pure water. A moderate lowering was also observed for the entire water soluble aerosol sample, including both organic and inorganic compounds, where the surface tension was decreased by between 2% (71.2 mN/m) and 13% (63.3 mN/m).

scholarly journals Widening the gap between measurement and modelling of secondary organic aerosol properties?

2010 ◽  
Vol 10 (6) ◽  
pp. 2577-2593 ◽  
Author(s):  
N. Good ◽  
D. O. Topping ◽  
J. Duplissy ◽  
M. Gysel ◽  
N. K. Meyer ◽  
...  
Keyword(s):  
Surface Tension ◽  
Water Activity ◽  
Condensation Nucleus ◽  
Organic Aerosol ◽  
Solute Concentration ◽  
Complex Model ◽  
Cloud Condensation Nucleus ◽  
Saturated Water ◽  
Cloud Activation ◽  
Ccn Activity

Abstract. The link between measured sub-saturated hygroscopicity and cloud activation potential of secondary organic aerosol particles produced by the chamber photo-oxidation of α-pinene in the presence or absence of ammonium sulphate seed aerosol was investigated using two models of varying complexity. A simple single hygroscopicity parameter model and a more complex model (incorporating surface effects) were used to assess the detail required to predict the cloud condensation nucleus (CCN) activity from the sub-saturated water uptake. Sub-saturated water uptake measured by three hygroscopicity tandem differential mobility analyser (HTDMA) instruments was used to determine the water activity for use in the models. The predicted CCN activity was compared to the measured CCN activation potential using a continuous flow CCN counter. Reconciliation using the more complex model formulation with measured cloud activation could be achieved widely different assumed surface tension behavior of the growing droplet; this was entirely determined by the instrument used as the source of water activity data. This unreliable derivation of the water activity as a function of solute concentration from sub-saturated hygroscopicity data indicates a limitation in the use of such data in predicting cloud condensation nucleus behavior of particles with a significant organic fraction. Similarly, the ability of the simpler single parameter model to predict cloud activation behaviour was dependent on the instrument used to measure sub-saturated hygroscopicity and the relative humidity used to provide the model input. However, agreement was observed for inorganic salt solution particles, which were measured by all instruments in agreement with theory. The difference in HTDMA data from validated and extensively used instruments means that it cannot be stated with certainty the detail required to predict the CCN activity from sub-saturated hygroscopicity. In order to narrow the gap between measurements of hygroscopic growth and CCN activity the processes involved must be understood and the instrumentation extensively quality assured. It is impossible to say from the results presented here due to the differences in HTDMA data whether: i) Surface tension suppression occurs ii) Bulk to surface partitioning is important iii) The water activity coefficient changes significantly as a function of the solute concentration.

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