Can chemical effects on cloud droplet number rival the first indirect effect?

Nenes, Athanasios; Charlson, Robert J.; Facchini, M. C.; Kulmala, Markku; Laaksonen, A.; Seinfeld, John H.

doi:10.1029/2002gl015295

Cited by 209 publications

(247 citation statements)

References 17 publications

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“…11c). Overall, the results are in agreement with earlier studies (Nenes et al, 2002;Simmel et al, 2005) that investigated the dependence of cloud droplet number concentrations on the condensation coefficient. Moreover, Fig.…”

Section: Condensation Coefficientsupporting

confidence: 83%

“…In reality, the aerosol distribution is an aggregate of particles with different physicochemical properties, including different shapes, solubility, and chemical species (Kreidenweis et al, 2003;Nenes et al, 2002). Even if specified initial aerosol characteristics were to capture the variation of κ with size, how to track the evolution of κ as particles among different bins undergo coalescence and breakup remains a challenge.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Organic films can strongly impede the uptake of moisture by atmospheric aerosol particles, thus reducing the value of (Gill et al, 1983;Mozurkewich, 1986). Nenes et al (2002) Atmos. Chem.…”

Section: Summary Of Sensitivity Analysismentioning

confidence: 99%

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Understanding aerosol-cloud interactions in the development of orographic cumulus congestus during IPHEx

Duan

Petters

Barros

2017

Preprint

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Abstract.A new cloud parcel model (CPM) including activation, condensation, collision-coalescence, and lateral entrainment processes is presented here to investigate aerosol-cloud interactions (ACI) in cumulus development prior to rainfall onset. The CPM was employed along with ground based radar and surface aerosol measurements to predict the vertical structure of cloud formation at early stages and evaluated against airborne observations of cloud microphysics and 10 thermodynamic conditions during the Integrated Precipitation and Hydrology Experiment (IPHEx) over the Southern Appalachian Mountains. Further, the CPM was applied to explore the space of ACI physical parameters controlling cumulus congestus growth not available from measurements, and to examine how variations in aerosol properties and microphysical processes influence the evolution and thermodynamic state of clouds over complex terrain via sensitivity analysis. Modelling results indicate that aerosol-cloud droplet number concentration (CDNC) closure is achieved optimally to ~ 1.3% of the 15 observations for condensation coefficient ( ) = 0.01 and within 5% for 0.01< < 0.015, and the corresponding spectra in the predictions are in good agreement with IPHEx aircraft observations around the same altitude. This is in contrast with larger closure errors and high values reported in previous studies assuming adiabatic conditions. Entrainment is shown to govern the vertical development of clouds and the change of droplet numbers with height, and the sensitivity analysis suggests that entrainment strength and condensation process are mutually compensating to attain aerosol-CDNC closure. 20Simulated CDNC also exhibits high sensitivity to variations in initial aerosol concentration at cloud base, but weak sensitivity to aerosol hygroscopicity. Exploratory multiple-parcel simulations capture realistic time-scales of vertical development of cumulus congestus (deeper clouds and faster droplet growth). These findings provide new insights into determinant factors of mid-day cumulus congestus formation that can explain a large fraction of warm season rainfall in mountainous regions. 25

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Section: Condensation Coefficientsupporting

confidence: 83%

Section: Summary and Discussionmentioning

confidence: 99%

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Understanding aerosol-cloud interactions in the development of orographic cumulus congestus during IPHEx

Duan

Petters

Barros

2017

Preprint

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“…From the results of Sullivan et al (2009) large increases in hygroscopicity may result from mixing small amounts of highly soluble material to lower solubility material that has a high intrinsic hygroscopicity. Added water solubilizes the low-solubility core and induces non-linear response in mixing (Nenes et al, 2002, Kokkola et al, 2008. The orange points in Fig.…”

Section: Resultsmentioning

confidence: 99%

Inorganic salts interact with oxalic acid in submicron particles to form material with low hygroscopicity and volatility

et al. 2014

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Abstract. Volatility and hygroscopicity are two key properties of organic aerosol components, and both are strongly related to chemical identity. While the hygroscopicities of pure salts, di-carboxylic acids (DCA), and DCA salts are known, the hygroscopicity of internal mixtures of these components, as they are typically found in the atmosphere, has not been fully characterized. Here we show that inorganicorganic component interactions typically not considered in atmospheric models can lead to very strongly bound metalorganic complexes and greatly affect aerosol volatility and hygroscopicity; in particular, the bi-dentate binding of DCA to soluble inorganic ions. We have studied the volatility of pure, dry organic salt particles and the hygroscopicity of internal mixtures of oxalic acid (OxA, the dominant DCA in the atmosphere) and a number of salts, both mono-and divalent. The formation of very low volatility organic salts was confirmed, with minimal evaporation of oxalate salt particles below 75 • C. Dramatic increases in the cloud condensation nuclei (CCN) activation diameter for particles with di-valent salts (e.g., CaCl 2 ) and relatively small particle volume fractions of OxA indicate that standard volume additivity rules for hygroscopicity do not apply. Thus small organic compounds with high O : C ratios are capable of forming lowvolatility and very low hygroscopicity particles. Given current knowledge of the formation mechanisms of OxA and M-Ox salts, surface enrichment of insoluble M-Ox salts is expected. The resulting formation of an insoluble coating of metal-oxalate salts can explain low-particle hygroscopicities. The formation of particles with a hard coating could offer an alternative explanation for observations of glass-like particles without the need for a phase transition.

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“…It is well established that organic compounds (especially water-soluble organic compounds, WSOC) are ubiquitous in marine aerosol; they can interact with water and affect aerosol hygroscopicity, droplet surface tension, and Cloud Condensation Nuclei (CCN) activity [1][2][3][4][5][6]. As a result, marine aerosol organic matter can affect cloud droplet number concentration as much as 15% [7][8][9][10] and may exert a climatically important impact on clouds.…”

Section: Introductionmentioning

confidence: 99%

CCN Properties of Organic Aerosol Collected Below and within Marine Stratocumulus Clouds near Monterey, California

et al. 2015

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Abstract:The composition of aerosol from cloud droplets differs from that below cloud. Its implications for the Cloud Condensation Nuclei (CCN) activity are the focus of this study. Water-soluble organic matter from below cloud, and cloud droplet residuals off the coast of Monterey, California were collected; offline chemical composition, CCN activity and surface tension measurements coupled with Köhler Theory Analysis are used to infer the molar volume and surfactant characteristics of organics in both samples. Based on the surface tension depression of the samples, it is unlikely that the aerosol contains strong surfactants. The activation kinetics for all samples examined are consistent with rapid (NH4)2SO4 calibration aerosol. This is consistent with our current understanding of droplet kinetics for ambient CCN. However, the carbonaceous material in cloud drop residuals is OPEN ACCESSAtmosphere 2015, 6 1591 far more hygroscopic than in sub-cloud aerosol, suggestive of the impact of cloud chemistry on the hygroscopic properties of organic matter.

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Can chemical effects on cloud droplet number rival the first indirect effect?

Cited by 209 publications

References 17 publications

Understanding aerosol-cloud interactions in the development of orographic cumulus congestus during IPHEx

Understanding aerosol-cloud interactions in the development of orographic cumulus congestus during IPHEx

Inorganic salts interact with oxalic acid in submicron particles to form material with low hygroscopicity and volatility

CCN Properties of Organic Aerosol Collected Below and within Marine Stratocumulus Clouds near Monterey, California

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