Investigation of aerosol particle hygroscopicity and their cloud forming potential in the supercooled temperature range

该项目的目标是a）开发新的仪器，将气溶胶颗粒活化和吸湿生长测量的实验温度范围扩展到较低但与大气相关的温度（-25 ℃ ≤ T ≤ 0 ℃），B）随后分析无机和有机颗粒在该温度范围内的吸湿生长和活化行为，和c）测定这些化合物在低于0 ℃的温度下的有效吸湿性参数。这些目标将通过开发和应用一种能够在低于水熔点的温度下测量吸湿颗粒生长的新型吸湿性串联微分迁移率分析仪（LT-HTDMA）以及应用莱比锡气溶胶云相互作用模拟器（LACIS）进行0°C以下的活化测量来实现。实验将伴随着模型模拟，描述LACIS内部发生的耦合流体和粒子动力学过程，这是数据解释所必需的。生长和活化测量的实验结果将对照现有的科勒模型进行测试，目的是验证和/或将现有的有效吸湿性参数化扩展到0°C以下的温度。这种实验和理论方法的结合将大大有助于提高对中纬度地区云形成过程的认识。

This project aims at a) the development of new instrumentation 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 development and application of a novel Hygroscopicity Tandem Differential Mobility Analyzer (LT-HTDMA) capable of measuring hygroscopic particle growth at temperatures below the melting point of water and the application of the Leipzig Aerosol Cloud Interaction Simulator (LACIS) for the activation measurements below 0°C. 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. 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.