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Abstract New‐particle formation is important to aerosol–cloud interactions and thus climate, but for newly formed particles to become cloud condensation nuclei, they must grow and avoid scavenging by larger background particles. Whereas ion‐induced new‐particle formation and growth have received attention recently, here we study an opposing effect, blunting the enhancement due to ions, that has received less attention: Small charged particles are scavenged more efficiently due to their charge, and thus their survival probability is lower than that of their neutral counterparts. Through simulations, we show that particle survival is reduced, in some cases dramatically, matching updated theoretical predictions. We also show that the survival of charged particles is enhanced if particles lose their charge via neutralization; therefore, for ion‐induced nucleation to be important, the resulting charged particles must become neutral as soon as possible. Overall, the coagulation scavenging enhancement due to charge ought to lessen the influence of ions in new‐particle formation and growth.
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Measurement of the collision rate coefficients between atmospheric ions and multiply charged aerosol particles in the CERN CLOUD chamber
Abstract. Aerosol particles have an important role in Earth'sradiation balance and climate, both directly and indirectly throughaerosol–cloud interactions. Most aerosol particles in the atmosphere areweakly charged, affecting both their collision rates with ions and neutralmolecules, as well as the rates by which they are scavenged by other aerosolparticles and cloud droplets. The rate coefficients between ions and aerosolparticles are important since they determine the growth rates and lifetimesof ions and charged aerosol particles, and so they may influence cloudmicrophysics, dynamics, and aerosol processing. However, despite theirimportance, very few experimental measurements exist of charged aerosolcollision rates under atmospheric conditions, where galactic cosmic rays inthe lower troposphere give rise to ion pair concentrations of around 1000 cm−3. Here we present measurements in the CERN CLOUD chamber of therate coefficients between ions and small (<10 nm) aerosol particlescontaining up to 9 elementary charges, e. We find the rate coefficient of asingly charged ion with an oppositely charged particle increases from 2.0(0.4–4.4) × 10−6 cm3 s−1 to 30.6 (24.9–45.1) × 10−6 cm3 s−1 for particles with charges of 1 to9 e, respectively, where the parentheses indicate the ±1σuncertainty interval. Our measurements are compatible with theoreticalpredictions and show excellent agreement with the model ofGatti and Kortshagen (2008).
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- Award ID(s):
- 2132089
- PAR ID:
- 10437062
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Date Published:
- Journal Name:
- Atmospheric Chemistry and Physics
- Volume:
- 23
- Issue:
- 12
- ISSN:
- 1680-7324
- Page Range / eLocation ID:
- 6703 to 6718
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/acp-23-6703-2023
