New insights into precipitation development as affected by novel investigations on the limitation of large raindrops' sizes

为了改进降水预报的最终目标，重新研究了限制大雨滴大小(碰撞诱导的破裂)的基本机制，该机制在过去只通过很少的实验室实验进行了检验。它的影响是通过使用德国气象局的云解析业务天气预报模式进行的数值研究来估计的。研究分为两部分：首先，使用先进的流体力学程序进行了数值实验，其中最详细地跟踪了碰撞的大(雨)滴的碰撞和破裂。它们将通过实验室实验进行检验。如果过去几个实验的结果得到证实，这些结果提供的特征的值可能取决于特定的分手模式。新数据将用于ID-RAYSHAY模型。除了平衡雨滴尺寸谱在许多与降水物理有关的领域，例如在雷达气象学中很重要外，雨轴模型还提供了用于推导(更粗略的)破碎参数的基本值。然后，为实际应用开发了一种新的解体参数化方法。它将取代传统的公式，而传统的公式实际上是大量云微物理方案的一部分，该方案已经在德国气象局的天气预报模型的云解析版本中运行。首先，将进行敏感性研究，以评估新数据对分解过程对降水的影响。

To the ultimate goal to improve precipitation forecasts a basic mechanism limiting the size of large raindrops (collision-induced breakup), which has been examined in the very past by very few laboratory experiments only, is re-investigated. Its effect is estimated by numerical studies using a cloud-resolving operational weather forecast model of the German Weather Service. The studies are partitioned into two parts: At first numerical experiments with an advanced fluid-dynamics code were performed where the collision and the breakup of colliding large (rain)drops are followed in greatest detail. They will be checked by according laboratory experiments. The results provide characteristics whose values may depend on specific breakup modes if results of the few past experiments are confirmed. The new data will be used in a ID-rainshaft model. Besides equilibrium raindrop size spectra important in many fields related to precipitation physics as, e.g., in radar meteorology, the rainshaft model delivers basic values for deriving a (coarser) parameterization of breakup. Prom the latter values then a new parameterization of breakup is developed for operational applications. It will replace the traditional formulation which actually is part of a bulk cloudmicrophysical scheme running already in a cloud-resolving version of a weather forecast model of the German Weather Service. First sensitivity studies will be undertaken to assess the effect of the new data on the breakup process on precipitation.