Microphysics of ice particles at the polar summer mesopause (Microlce)

在80-90 km高度和150 K以下的温度下，大气层中层冰粒子可以在纳米尺度的大气烟粒子上成核。在有利的条件下，从地面上可以看到它们的云。这些冰粒改变了周围等离子体的电荷状态，因此伴随着雷达回波，称为极地中层夏季回波。这两种现象都可以通过地面遥感方法直接观测到，因此是对中层顶物理和动力过程的有价值的探索，否则就难以理解。这些信号的变化经常被用来推断这个高度区域的长期气候趋势。尽管这一重要性，我们缺乏有关冰的成核和生长过程中的热力学，化学和电环境的中层顶的基本知识。在这方面取得进展将大大提高中层大气模型的描述和预测能力，从而提高我们对中层顶区域在气候系统中的作用的认识。对这些过程的全面实验室实验已经成为可能，直到最近在卡尔斯鲁厄理工学院（KIT）建立了一个新的实验装置，它允许在现实的中间层条件下研究纳米粒子上的冰成核作用。在卡尔斯鲁厄实验组（T。L.）和Kühlungsborn的建模团队（M. R.）我们建议研究冰在由典型矿物如橄榄石组成的真实纳米颗粒上的成核和生长速率，并将研究结果应用到中间层模拟中。所有模型结果都将根据IAP Kühlungsborn的观测结果进行验证。此外，我们要确定的光学性能的不断增长的矿物/冰系统，以便与遥感信号进行直接比较。由罗斯托克大学和位于屈隆斯博恩的国际天文学研究所的小组提出的一个平行项目将补充预定的关于流星烟雾粒子的电子和光学特性的研究。

Mesospheric ice particle may nucleate in the polar summer mesopause at heights between 80–90 km and temperatures below ~150 K on nanometer sized meteoric smoke particles. Under favorable conditions, they are visible from ground as noctilucent clouds. These ice particles modify the charge state of the surrounding plasma and are therefore accompanied by radar echoes, known as polar mesosphere summer echoes. Both phenomena can be observed straightforwardly by remote sensing methods from the ground and thus are valuable probes for the otherwise elusive physical and dynamical processes at the mesopause. Changes in these signals are often used to infer long term climatic trends in this height region. Despite of this importance, we are lacking fundamental knowledge about the nucleation and growth processes of ice in the thermodynamic, chemical and electrical environment of the mesopause. Progress in this understanding would significantly enhance the descriptive and predictive capabilities of mesospheric models and thus our understanding of the role of the mesopause region in the climate system. Comprehensive laboratory experiments on these processes have become possible only recently with the establishment of a new experimental setup at the Karlsruhe Institute of Technology (KIT), which allows to study ice nucleation on nanoparticles under realistic mesospheric conditions on well characterized mineral nanoparticles. In close collaboration between the experimental group in Karlsruhe (T. L.) and the modeling team in Kühlungsborn (M. R.) we propose to study the nucleation and growth rates of ice on realistic nanoparticles composed of typical minerals as olivine and to implement the findings into mesospheric modeling. All model results will be validated versus observational results available at the IAP Kühlungsborn. Furthermore we want to determine the optical properties of the growing mineral/ice systems to allow for a direct comparison with remote sensing signals. A parallel project (ELOMA) proposed by groups from the University of Rostock and the IAP in Kühlungsborn will complement the scheduled research with respect to the electronic and optical properties of the meteoric smoke particles.