The research project will investigate the relation between microphysical properties of sub-cloud aerosols and clouds referring to droplet number and droplet size spectrum, which can contribute to a better understanding of the first indirect aerosol effect, one of the most concerning and significant uncertainties in climate change. The relation will be investigated by long term detailed in situ measurements of droplet activation in 120 m height and remote sensing observations (Sunphotometer, radar, microwave radiometer, and ceilometer).

By statistical analysis of the long term observations, suitable time periods of well-mixed planetary boundary layer conditions will be filtered out, in which droplet activation of the sub-cloud aerosols may be related to cloud microphysical properties. The goal is to improve the predictability of cloud microphysical properties (droplet number concentration, droplet size spectrum, and cloud optical properties) based on aerosol properties (critical parameters of droplet activation).

Figure 1: Research motivation. Figure 2: In-situ CCN measurement instruments: Cloud Condensation Nuclei Counter(CCN-C), Condensation Particle Counter (CPC), Differential Mobility Analyzer.