Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth Leibniz Institute for Tropospheric Research, Permoserstraße 15, 04318 Leipzig, Germany
12 Jul 2013
Received: 11 April 2012 – Published in Atmos. Chem. Phys. Discuss.: 03 May 2012 Abstract. This study examines the hygroscopicity of newly formed particles (diameters
range 25–45 nm) during two atmospheric new particle formation (NPF) events
in the German mid-level mountains during the Hill Cap Cloud Thuringia 2010
(HCCT-2010) field experiment. At the end of the NPF event involving clear
particle growth, we measured an unusually high soluble particle fraction of
58.5% at 45 nm particle size. The particle growth rate contributed
sulfuric acid condensation only accounts for around 6.5% of the observed
growth rate. Estimations showed that sulfuric acid condensation explained,
however, only around 10% of that soluble particle fraction. Therefore,
the formation of additional water-soluble matter appears imperative to
explain the missing soluble fraction. Although direct evidence is missing,
we consider water-soluble organics as candidates for this mechanism. For the
case with clear growth process, the particle growth rate was determined by
two alternative methods based on tracking the mode diameter of the
nucleation mode. The mean particle growth rate obtained from the inter-site
data comparison using Lagrangian consideration is 3.8 (± 2.6) nm h−1.
During the same period, the growth rate calculated based on one
site data is 5.0 nm h−1 using log-normal distribution function method.
In light of the fact that considerable uncertainties could be involved in both methods,
we consider both estimated growth rates consistent.
Revised: 10 June 2013 – Accepted: 12 June 2013 – Published: 12 July 2013
Citation: Wu, Z., Birmili, W., Poulain, L., Wang, Z., Merkel, M., Fahlbusch, B., van Pinxteren, D., Herrmann, H., and Wiedensohler, A.: Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth, Atmos. Chem. Phys., 13, 6637-6646, doi:10.5194/acp-13-6637-2013, 2013.