Abstract

A parameterization of the activation of a lognormal size distribution of aerosols to form cloud droplets is extended to the case of multiple externally mixed lognormal modes, each composed of a uniform internal mixture of soluble and insoluble material. The Köhler theory is used to relate the aerosol size distribution and composition to the number activated as a function of maximum supersaturation. The supersaturation balance is used to determine the maximum supersaturation, accounting for particle growth both before and after the particles are activated. Comparison of the parameterized activation of two competing aerosol modes with detailed numerical simulations of the activation process yields agreement to within 10% under a wide variety of conditions, including diverse size distributions, number concentrations, compositions, and updraft velocities. The parametization error exceeds 10% only when the mode radius of the two size distributions differs by an order of magnitude. Errors for the mass fraction activated are always much less than errors for the number fraction activated.

Keywords

SupersaturationAerosolLog-normal distributionParticle sizeParticle-size distributionRADIUSDistribution functionParticle (ecology)Particle numberMass fractionMechanicsThermodynamicsStatistical physicsPhysicsMaterials scienceChemistryMeteorologyMathematicsStatisticsVolume (thermodynamics)Physical chemistryGeology

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Publication Info

Year
2000
Type
article
Volume
105
Issue
D5
Pages
6837-6844
Citations
1048
Access
Closed

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Hayder Abdul‐Razzak, S. J. Ghan (2000). A parameterization of aerosol activation: 2. Multiple aerosol types. Journal of Geophysical Research Atmospheres , 105 (D5) , 6837-6844. https://doi.org/10.1029/1999jd901161

Identifiers

DOI
10.1029/1999jd901161