Combined Active Remote Sensing and Modeling of Ice Nucleating Particles and Ice Crystal Flux (COARSEMIX)

云层遍布全球，覆盖了地球表面30%以上的面积。因此，它们通过永久性地改变地球的反照率，对大气的辐射平衡产生了强烈的影响。推动云演化的过程，特别是通过非均相冻结的冰相变，其在大气环流模式中的简化表示目前引起了大量的研究活动。一个基本的问题是，自由对流层气溶胶以多大的速率输送到混合云层中，并以云凝结核和冰核粒子(INP)补充。在模拟和观测的基础上，没有对云层升高(高积云、高层云)的这一过程进行详细的描述，尽管云层升高是气溶胶-云动力学相关研究的理想选择。我们提出了一项研究，将根据主动遥感观测(激光雷达/雷达)和详细的数值云模拟，调查这些云层内的气溶胶夹带和冰粒的形成。将通过最先进的数值云分辨模拟来研究高空云层内的气溶胶输送。对于进入云层的INP通量和流出云层的冰晶通量之间的同时闭合，模式必须能够显式地模拟气溶胶输送和随后在云层中的冰形成。最近几年，TROPOS发展了这样的数值云模式。这里提出的COARSEMIX(联合主动遥感与冰核粒子和冰晶通量模拟)项目将是第一个关于INP和冰晶数浓度的联合遥感/模拟闭合实验。它将提供关于气溶胶、动力学、冰形成、云形成和降水之间相互作用的信息。由于模拟和观测部分之间的密切相互作用，该项目将能够将新的气溶胶/冰参数直接应用到模式中。

Clouds occur globally and always cover more than 30% of the Earth's surface. They have, thus, a strong influence on the radiative balance of the atmosphere by permanently changing Earth's albedo. The processes driving cloud evolution are poorly understood, especially ice phase transitions via heterogeneous freezing, and thus their simplified representation in atmospheric circulation models presently motivates numerous research activities. It is a fundamental question, at what rate free-tropospheric aerosol is transported into a mixed phase cloud layer, resupplying it with cloud condensation nuclei and ice nucleating particles (INP). A detailed description of this process for elevated cloud layers (altocumulus, altostratus) on the basis of modeling and observation is absent, although elevated cloud layers are ideal for aerosol-cloud-dynamics related studies. We propose a study that will investigate aerosol entrainment and the formation of ice particles within such cloud layers, based on active remote-sensing observations (lidar/radar) and detailed numerical cloud modeling. The aerosol transport within elevated cloud layers will be studied by means of state-of-the-art numerical cloud-resolving modeling. For a simultaneous closure between the flux of INP into a cloud layer and the flux of ice crystals out of it, the models have to be capable of explicitly simulating aerosol transport and subsequent ice formation in cloud layers. Within the recent years, such numerical cloud models have been developed at TROPOS. The here proposed COARSEMIX (Combined Active Remote SEnsing and Modeling of Ice-nucleating particles and ice crystal fluX) project will be the first combined remote-sensing/modeling closure experiment for the number concentrations of INP and ice crystals. It will deliver information about the interaction between aerosols, dynamics, ice formation, cloud formation and precipitation. The project will enable direct implementation of new aerosol/ice parameterization into models, due to the close interaction between the modeling and the observational components.