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

我们从实验上研究了大气成冰粒子(INP)的丰度、化学成分和混合状态，即允许混合相云中冰的非均匀形成的这种粒子。这些信息对于理解大气中的降水机制是不可避免的。气象模型使用这些数据的参数化来预测降水的发展。Inp很少见：只有1/10.000到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。因纽特人研究单位采用了几种不同的方法，将INP与其他大部分大气颗粒区分开来。然后收集通过这些不同方法识别和分离的单个颗粒，并用电子显微镜分析它们的大小、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在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，并对其进行分析。INP计数器在流动管反应器中的周围气溶胶上生长冰晶，而INP计数器冰箱在硅衬底上静电沉淀的大气颗粒上生长冰。另外两种方法，名为Ice-CVI和ISI，试图分离INP，方法是首先将加速云气流中的冰晶与其他成分分离，基于它们较高的惯性，然后蒸发冰，将INP留下来供后续收集和分析。对所有四种方法的结果进行了比较。在实地实验期间，将分析来自不同大气环境(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。法兰克福附近的陶努斯天文台将在第1-3年对环境空气中INP沉积和浸泡模式的数值浓度进行例行分析，并筛选季节性、潜在来源地区(沙漠、工业)以及决定其变异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.