A review of current knowledge concerning size-dependent aerosol removal--颗粒学报PARTICUOLOGY

Zhang, L., & Vet, R. (2006). A review of current knowledge concerning size-dependent aerosol removal. China Particuology, 4(6), 272-282. https://doi.org/10.1016/S1672-2515(07)60276-0

A review of current knowledge concerning size-dependent aerosol removal

Leiming Zhang ^*, Robert Vet

Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, M3H 5T4, Canada

10.1016/S1672-2515(07)60276-0

Volume 4, Issue 6, December 2006, Pages 272-282

Received 13 April 2006, Accepted 5 October 2006, Available online 14 December 2007.

E-mail: leiming.zhang@ec.gc.ca

Highlights

Abstract

The status of current knowledge on size-dependent aerosol removal by dry and wet processes, including dry deposition and impaction and nucleation scavenging, is reviewed. The largest discrepancies between theoretical estimations and measurement data on dry deposition and below-cloud scavenging are for submicron particles. Early dry deposition models, which developed based on chamber and wind tunnel measurements, tended to underestimate dry deposition velocity (V_d) for submicron particles by around one order of magnitude compared to recent field measurements. Recently developed models are able to predict reasonable V_d values for submicron particles but shift unrealistically the predicted minimum V_d to larger particle sizes. Theoretical studies of impaction scavenging of aerosol particles by falling liquid drops also substantially underestimate the scavenging coefficients for submicron particles. Empirical formulas based on field measurements can serve as an alternative to the theoretical scavenging models. Future development of size-resolved impaction scavenging models needs to include more precipitation properties (e.g., droplet surface area) and to be evaluated by detailed cloud microphysical models and available measurements. Several recently developed nucleation scavenging parameterizations for in-cloud removal of interstitial aerosol give comparable results when evaluated against parcel models; however, they need to be verified once suitable field measurements are available. More theoretical and field studies are also needed in order to better understand the role of organic aerosols in the nucleation scavenging process.

Graphical abstract

Keywords

atmospheric particles; size-dependent removal; dry deposition; impaction scavenging; nucleation scavenging; measurement and modeling

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