Chemical and mineralogical characterization of ice nucleating particles and ice particle residuals

我们调查的丰度，化学成分和混合状态的大气冰成核粒子（INP）的实验，即这样的粒子，允许在混合相云中的冰的非均匀形成。这些信息对于理解大气中降水的机制是不可避免的。气象模型使用这些数据的参数化来预测降水的发展。INP是罕见的：只有1/10.000至1/100.000的大气颗粒物是INP。我们使用物理方法从空气的其他成分中识别和分离INP，然后使用先进的电子显微镜对单个颗粒进行摄影，计数和矿物学分析。 INUIT研究部门采用了几种不同的方法来区分INP和其他大气颗粒物。然后收集通过这些不同方法识别和分离的单个颗粒，并通过电子显微镜分析其尺寸，形态，混合状态和化学成分。其中两种方法（INP计数器FINCH和FRIDGE）通过将气溶胶样品暴露于零度以下的温度和过饱和的水蒸气中，从而在INP上生长宏观冰晶来识别INP。然后将冰晶和INP从气溶胶中分离出来，并对INP进行分析。INP计数器FINCH在流管反应器中的环境气溶胶上生长冰晶，而INP计数器FRIDGE在静电沉淀在硅衬底上的大气颗粒上生长冰。另外两种方法，名为Ice-CVI和ISI，试图通过首先将加速的云空气流中的冰晶与其他成分分离来分离INP，基于其较高的惯性，然后蒸发冰，留下INP用于随后的收集和分析。所有四种方法的结果进行了比较。将在实地实验中分析来自各种大气环境（中欧、少女峰、地中海、沙漠尘埃）的气溶胶。模型和标准气溶胶将在实验室实验中进行研究。 在法兰克福附近的Taunus天文台环境空气中沉积和浸没模式下的INP数浓度将在1-3年进行常规分析，并筛选季节性、潜在源区（沙漠、工业）以及决定其可变性的主要因素或成分（如生物材料、矿物粉尘）。

We investigate the abundance, chemical composition and mixing state of atmospheric ice nucleating particles (INP) experimentally, i.e. of such particles that allow the heterogeneous formation of ice in mixed-phase clouds. This information is inevitable to understand the mechanisms of precipitation in the atmosphere. Meteorological models use parameterizations of such data to predict the development of precipitation. INP are rare: only 1 in 10.000 to 1 in 100.000 of atmospheric particles is an INP. We identify and isolate INP from other constituents of air using physical methods, followed by photography, counting and mineralogical analysis of the single particles, using advanced electron microscopy. The INUIT research unit applies several different approaches to distinguish INP from the bulk of other atmospheric particles. The individual particles identified and separated by these different methods are then collected and analyzed by electron microscopy for their size, morphology, mixing state, and chemical composition. Two of the methods (INP counters FINCH and FRIDGE) identify the INP by exposing an aerosol sample to subzero temperatures and supersaturated water vapor, thus growing macroscopic ice crystals on the INP. Ice crystals and thus INP are then separated from aerosol, and INP analyzed. The INP counter FINCH grows ice crystals on ambient aerosol in a flow tube reactor, while the INP counter FRIDGE grows ice on atmospheric particles that were precipitated electrostatically on a silicon substrate. Two other methods, named Ice-CVI and ISI, attempt to isolate INP by first separating the ice crystals in a flow of accelerated cloud air from other constituents, based on their higher inertia, and then evaporate the ice, leaving the INP behind for subsequent collection and analysis. Results from all four methods are compared. Aerosols from various atmospheric environments (central Europe, Jungfraujoch, Mediterranean, desert dust) will be analyzed during field experiments. Model and standard aerosols will be investigated in lab experiments. The number concentration of INP in the deposition and immersion modes in ambient air at Taunus Observatory near Frankfurt will be analyzed routinely in years 1-3 and screened for a seasonality, potential source areas (desert, industry), and for the main factors or components (such as biological material, mineral dust) that determine its variability.