(Milton Park : Taylor & Francis, 2014) Zieger, Paul; Fierz-Schmidhauser, Rahel; Poulain, Laurent; Müller, Thomas; Birmili, Wolfram; Spindler, Gerald; Wiedensohler, Alfred; Baltensperger, Urs; Weingartner, Ernest
The influence of aerosol water uptake on the aerosol particle light scattering was examined at the regional
continental research site Melpitz, Germany. The scattering enhancement factor f(RH), defined as the aerosol
particle scattering coefficient at a certain relative humidity (RH) divided by its dry value, was measured using a
humidified nephelometer. The chemical composition and other microphysical properties were measured in
parallel. f(RH) showed a strong variation, e.g. with values between 1.2 and 3.6 at RH85% and l550 nm.
The chemical composition was found to be the main factor determining the magnitude of f(RH), since
the magnitude of f(RH) clearly correlated with the inorganic mass fraction measured by an aerosol mass
spectrometer (AMS). Hysteresis within the recorded humidograms was observed and explained by long-range
transported sea salt. A closure study using Mie theory showed the consistency of the measured parameters.
