PINEair - A new instrument for aircraft-based in situ measurements of ice nucleating particles at cirrus formation conditions

高空卷云形成于对流层上层，温度低于-40°C。它们由冰晶组成，对地球的气候有冷却和加热的作用。这两种过程中哪一种起主导作用，除其他因素外，还取决于卷云冰晶的数量、浓度和大小。这反过来又取决于大气中所谓的冰核粒子（INPs）的丰度和类型。气溶胶颗粒是大气气溶胶颗粒中非常小的一部分，它们来自大量不同的来源，因此表现出各种各样的大小、形状和化学成分。到目前为止，还没有基于飞机的仪器可以直接测量低温下大气中INPs的丰度。作为该项目的一部分，我们建议首次建造这样一台仪器，并对其进行认证，以便在HALO研究飞机上进行测量。这种名为PINEair（便携式冰成核实验-飞机版）的新型创新仪器基本上就像一个云膨胀室，类似于卡尔斯鲁厄理工学院（KIT）的AIDA云室。这台紧凑的全自动仪器将首次以高灵敏度和高时间分辨率测量对流层上层INP浓度。由此产生的数据集将有助于更好地了解卷云的形成，并更好地量化它们在地球气候系统中的作用。

High-altitude cirrus clouds are formed in the upper troposphere at temperatures below about -40°C. They consist of ice crystals, which have both a cooling and a heating contribution to the Earth’s climate. Which of the two processes dominates depends, among other factors, on the number concentration and size of the cirrus cloud ice crystals. This in turn depends on the abundance and type of so-called ice nucleating particles (INPs) in the atmosphere. INPs are a very minor fraction of atmospheric aerosol particles, which originate from a large number of different sources, and therefore exhibit a large variety of sizes, shapes and chemical composition. So far, no aircraft-based instrument exists to directly measure the atmospheric abundance of INPs at low temperatures. As part of this project, we suggest to build such an instrument for the first time and to certify it for measurements onboard the HALO research aircraft. This new and innovative instrument called PINEair (Portable Ice Nucleation Experiment – aircraft version) basically works like a cloud expansion chamber, similar to the AIDA cloud chamber of the Karlsruhe Institute of Technology (KIT). The compact and fully automated instrument will allow to measure for the first time upper tropospheric INP concentrations with high sensitivity and time resolution. The resulting data set will contribute to a better understanding of the formation of cirrus clouds, and to better quantify their role in the Earth’s climate system.