Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

Wonaschütz, Anna; Coggon, Matthew M.; Sorooshian, Armin; Modini, Robin L.; Frossard, A. A.; Ahlm, Lars; Mülmenstädt, J.; Roberts, Grégory; Russell, Lynn M.; Dey, S.; Brechtel, Fred J.; Seinfeld, John H.

doi:10.5194/acp-13-9819-2013

Cited by 32 publications

(35 citation statements)

References 80 publications

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“…These results are consistent with recently published work [18,64] that shows SOMA as a significant contributor to CCN activity in marine regions. Finally, all samples display similar droplet growth kinetics to CCN composed of (NH4)2SO4, suggesting that water-soluble organics do not significantly impact the growth rate of CCN.…”

Section: Summary and Implicationssupporting

confidence: 83%

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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Section: Summary and Implicationssupporting

confidence: 83%

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

et al. 2015

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“…For example, Ruehl et al [] have shown that products from α ‐pinene ozonolysis reduce the surface tension of NaCl particles by 50–75%, implying that surface active products may enhance water uptake in certain aerosols. Wonaschütz et al [] found that in the study region examined here, initially hydrophobic organics emitted from an ocean vessel yielded higher CCN after atmospheric aging.…”

Section: Resultsmentioning

confidence: 81%

Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California

et al. 2014

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During the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E‐PEACE) and 2013 Nucleation in California Experiment (NiCE) field campaigns, a predominantly organic aerosol (> 85% by mass) was observed in the free troposphere over marine stratocumulus off the coast of California. These particles originated from a densely forested region in the Northwestern United States. The organic mass spectrum resolved by positive matrix factorization is consistent with the mass spectra of previously measured biogenic organic aerosol. Particulate organic mass exhibits a latitudinal gradient that corresponds to the geographical distribution of vegetation density and composition, with the highest concentration over regions impacted by densely populated monoterpene sources. Due to meteorological conditions during summer months, cloud‐clearing events transport aerosol from the Northwestern United States into the free troposphere above marine stratocumulus. Based on the variation of meteorological variables with altitude, dry air containing enhanced biogenic organic aerosol is shown to entrain into the marine boundary layer. Fresh impacts on cloud water composition are observed north of San Francisco, CA which is consistent with fresh continental impacts on the marine atmosphere at higher latitudes. Continental aerosol size distributions are bimodal. Particles in the 100 nm mode are impacted by biogenic sources, while particles in the ∼ 30 nm mode may originate from fresh biogenic emissions. Continental aerosol in the 100 nm mode is cloud condensation nuclei active and may play a role in modulating marine stratocumulus microphysics.

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“…A bulk hygroscopicity parameter (κ) is derived using the method of Petters and Kreidenweis (2007) and by assuming total activation above a critical activation diameter, such that the CCN concentration exactly matches the concentration of particles exceeding this critical diameter (Furutani et al, 2008; Burkart et al, 2011; Wonaschütz et al, 2013). Hygroscopicity decreases concurrently with the morning traffic signature (Fig.…”

Section: Climatological Resultsmentioning

confidence: 99%

On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

et al. 2015

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A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012–2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Average CCN concentrations are typically lowest in spring (233 cm−3), highest in winter (430 cm−3) and have a secondary peak during the North American monsoon season (July to September; 372 cm−3). There is significant variability outside of seasonal patterns, with extreme concentrations (1 and 99 % levels) ranging from 56 to 1945 cm−3 as measured during the winter, the season with highest variability. Modeled CCN concentrations based on fixed chemical composition achieve better closure in winter, with size and number alone able to predict 82% of the variance in CCN concentration. Changes in aerosol chemical composition are typically aligned with changes in size and aerosol number, such that hygroscopicity can be parameterized even though it is still variable. In summer, models based on fixed chemical composition explain at best only 41% (pre-monsoon) and 36% (monsoon) of the variance. This is attributed to the effects of secondary organic aerosol (SOA) production, the competition between new particle formation and condensational growth, the complex interaction of meteorology, regional and local emissions and multi-phase chemistry during the North American monsoon. Chemical composition is found to be an important factor for improving predictability in spring and on longer timescales in winter. Parameterized models typically exhibit improved predictive skill when there are strong relationships between CCN concentrations and the prevailing meteorology and dominant aerosol physicochemical processes, suggesting that similar findings could be possible in other locations with comparable climates and geography.

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Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

Cited by 32 publications

References 80 publications

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

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

Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California

On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert

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