Hygroscopic properties and extinction of aerosol particles at ambient relative humidity in South-Eastern China

Eichler, H.; Cheng, Y. F.; Birmili, W.; Nowak, A.; Wiedensohler, A.; Brüggemann, E.; Gnauk, T.; Herrmann, H.; Althausen, D.; Ansmann, A.; Engelmann, R.; Tesche, Matthias; Wendisch, M.; Zhang, Y. H.; Hu, M.; Liu, S.; Zeng, L. M.

Author

Eichler, H.

Cheng, Y. F.

Birmili, W.

Nowak, A.

Wiedensohler, A.

Brüggemann, E.

Gnauk, T.

Herrmann, H.

Althausen, D.

Ansmann, A.

Engelmann, R.

Tesche, Matthias

Wendisch, M.

Zhang, Y. H.

Hu, M.

Liu, S.

Zeng, L. M.

Abstract

During the "Program of Regional Integrated Experiments of Air Quality over Pearl River Delta 2004 (PRIDE-PRD2004)" hygroscopic properties of particles in the diameter range 22 nm to 10 μ m were determined. For that purpose, a Humidifying Differential Mobility Particle Sizer (H-DMPS) and a Micro-Orifice Uniform Deposition Impactor (MOUDI) were operated. The derived size-dependent particle hygroscopic growth factors were interpolated to ambient relative humidity (RH) and used to calculate the particle number size distributions (PNSDs) at ambient conditions. A comparison between the modeled particle extinction coefficients (σext, Mie) and those observed with a Raman lidar was made. It is shown that the particle extinction coefficient (σext) at ambient RH can be properly estimated with Mie-model calculations based on the in situ physico-chemical measurements of dry and humidified PNSD and chemical composition.