The impact of aerosol size-dependent hygroscopicity and mixing state on the cloud condensation nuclei potential over the north-east Atlantic

We present an aerosol cloud condensation nuclei (CCN) closure study over the north-east Atlantic Ocean using six approximating methods. The CCN number concentrations (N.sub.CCN) were measured at four discrete supersaturations (SSs; 0.25 %, 0.5 %, 0.75 % and 1.0 %). Concurrently, aerosol number size...

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Bibliographic Details
Published in:Atmospheric chemistry and physics 2021-06, Vol.21 (11), p.8655-8675
Main Authors: Xu, Wei, Fossum, Kirsten N, Ovadnevaite, Jurgita, Lin, Chunshui, Huang, Ru-Jin, O'Dowd, Colin, Ceburnis, Darius
Format: Article
Language:English
Subjects:
Aerosol clouds
Aerosol effects
Aerosols
Air masses
Approximation
Biological activity
Chemical composition
Climate change
Cloud condensation nuclei
Clouds
Condensation
Condensation nuclei
Growth factors
Humidity
Hydrophobicity
Hygroscopicity
Marine aerosols
Marine pollution
Mass spectrometry
Methods
Modes
Nucleus
Probability density function
Probability density functions
Probability theory
Radiation
Saturation
Size distribution
Statistical analysis
Temporal variability
Temporal variations
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Summary:We present an aerosol cloud condensation nuclei (CCN) closure study over the north-east Atlantic Ocean using six approximating methods. The CCN number concentrations (N.sub.CCN) were measured at four discrete supersaturations (SSs; 0.25 %, 0.5 %, 0.75 % and 1.0 %). Concurrently, aerosol number size distribution, sub-saturation hygroscopic growth factor and bulk PM.sub.1 chemical composition were obtained at matching time resolution and after a careful data validation exercise. Method A used a constant bulk hygroscopicity parameter κ of 0.3; method B used bulk PM.sub.1 chemical composition measured by an aerosol mass spectrometer (AMS); method C utilised a single growth factor (GF) size (165 nm) measured by a humidified tandem differential mobility analyser (HTDMA); method D utilised size-dependent GFs measured at 35, 50, 75, 110 and 165 nm; method E divided the aerosol population into three hygroscopicity modes (near-hydrophobic, more-hygroscopic and sea-salt modes), and the total CCN number in each mode was cumulatively added up; method F used the full-size-scale GF probability density function (GF-PDF) in the most complex approach. The studied periods included high-biological-activity and low-biological-activity seasons in clean marine and polluted continental air masses to represent and discuss the most contrasting aerosol populations.
ISSN:1680-7324
1680-7316
1680-7324
DOI:10.5194/acp-21-8655-2021