Cloud condensation nuclei (CCN) measurements with the HALO aircraft during EMeRGe in European and Asian airspace

During the EMeRGe campaign we employed a cloud condensation nuclei counter (CCNC) on board the research aircraft HALO. The instrument was located in the CCN-Rack probing together with a single particle soot photometer (SP2) and a multi-impactor for sampling different air masses on silica nitrate substrates. The aerosol particles were sampled through the HALO Aerosol Submicrometer Inlet (HASI). The measurements have been performed with a two column continuous-flow longitudinal thermal-gradient instrument (CCN-200) manufactured by DMT. The CCN-200 measures the CCN number concentration as a function of water vapor supersaturation (S). These measurements are performed by changing S within one column from 0.10 % up to 1.00 % using 12 different supersaturations and keeping S constant within the second column (S = 0.38 %) to ensure baseline data with 1 Hz time resolution. The different supersaturations are created by changing the flow while setting a fixed temperature difference.Purpose of EMeRGe is to quantify and qualify outflows of megacities, as well as their transport and transformation in the atmosphere. Therefore, measurement flights were performed in the European airspace in 2017, probing aerosol properties over cities like London, Barcelona and Rome. In March 2018, the same set of instruments was probing the outflows of Asian megacities like Taipei, Manila and aged pollution from China Mainland. Furthermore, Japanese and South Korean outflows could be probed. The measurements took place in altitudes between 0.3 km and 13 km ASL. The scientific objective is to investigate the effect of different pollution states on aerosol and CCN properties.