DFG Project "Investigation of aerosol particle hygroscopicity and their cloud forming potential in the supercooled temperature range (-25°C ≤ T ≤ 0°C)"
This project aims at a) the development of new experimental set-up for the expansion of the experimental temperature range of aerosol particle activation and hygroscopic growth measurements down to low, but atmospheric relevant temperatures (-25°C ≤ T ≤ 0°C), b) the subsequent analysis of hygroscopic growth and activation behaviour of inorganic and organic particles in this temperature range, and c) the determination of an effective hygroscopicity parameter for these compounds for temperatures below 0°C.
These goals will be achieved via the application of the Leipzig Aerosol Cloud Interaction Simulator (LACIS) for the activation measurements below 0°C and the modification of the LACIS mobile (References, Henning et al. 2012) to be capable of measuring hygroscopic particle growth at temperatures below the melting point of water and. The experiments will be accompanied by model simulations describing the coupled fluid and particle dynamical processes taking place inside LACIS which are necessary for data interpretation (Ice-particle growth). The experimental results of growth and activation measurements will be tested against existing Köhler models with the goal of verifying and / or expanding existing effective hygroscopicity parameterizations to temperatures below 0°C. This combination of experimental and theoretical methods will significantly contribute to improving the understanding of the cloud forming processes in the mid-latitudes.
Henning, S., et al. (2012), Hygroscopic growth and droplet activation of soot particles: Uncoated, succinic or sulfuric acid coated, Atmos. Chem. Phys., 12(10), 4525-4537.