Synergie eines effizienten polarimetrischen Radarvorwärtsoperators und eines hochentwickelten Klassifizierungsalgorithmus zur verbesserten Repräsentierung von Hydrometeoren im ICON-Modell (Operation Hydrometeors Part II)

在第一阶段，“水流星行动”提供了一个有效的极化正演运算器，作为融合雷达极化测量和大气模型所需的特别优先方案的基本先决条件。非极化高效模块化体积雷达OPerato(EMVORADO)已扩展到假设降水雷达波长为扁球体的偏振测量，在数值预报模式COSMO和ICON和独立框架中在线实施。我们还开发了一种基于聚类的复杂和更健壮的水流星分类(HMC)算法，该算法具有从极化雷达观测和基于EMVORADO图标模拟的合成变量估计水流星分配比的额外能力。利用开发的工具，我们采用双重策略，基于先进的基于雷达的水流星分类和量化，以及多变量观测和合成极化信号分布的直接比较，评估了层状雨中的极化特征和水流星。对ICON中的二阶矩云微物理参数化进行了一些改进。第二阶段进一步完善了所开发的工具，以扩大它们的适用性。我们改进了EMVORADO的熔化方案，潜在地还连接了一个散射数据库，并改进了我们的新HMC，使水流星团能够在0°C水平上延伸。随着这些发展，我们用我们的DUAL策略评估和改进了针对不同模式缺陷的另外三个关键偏振特征的表示：(1)增强的微分反射率ZDR柱将指导雨滴冻结过程的改进，(2)表面附近的ZDR是雨滴尺寸分布更好地参数化的关键标志，以及(3)树枝生长层中的偏振变量显示了改进和扩展ICON中冰微物理过程(例如次生冰产生)的表示的路径。最后，我们将利用极化衍生的信息在ICON中进行间接数据同化。根据项目的发展，我们吸收了ZDR列对象和/或来自我们新的HMC的分割率，很可能是以分类排名信息的形式。

In Phase 1 ‘Operation Hydrometeors’ provided an efficient polarimetric forward operator as a fundamental prerequisite to the Special Priority Programme required for the fusion of radar polarimetry and atmospheric modelling. The non-polarimetric Efficient Modular VOlume RADar OPerato (EMVORADO) has been extended to polarimetry assuming oblate spheroids at precipitation radar wavelengths in online implementations in the NWP-models COSMO and ICON and a stand-alone framework. We also developed a sophisticated and more robust hydrometeor classification (HMC) algorithm based on clustering with the additional capability to estimate hydrometeor partitioning ratios from both polarimetric radar observations and synthetic variables based on ICON simulations applying EMVORADO. With the tools developed, we evaluated polarimetric signatures and hydrometeors in stratiform rain employing a dual strategy, based on advanced radar-based hydrometeor typing and quantification and a direct comparison of multivariate observed and synthetic polarimetric signal distributions. Some improvements of the two-moment cloud microphysics parameterization in ICON resulted from this already.Phase 2 further refines the developed tools to broaden their applicability. We improve the melting scheme in EMVORADO, potentially also interface a scattering data base, and refine our new HMC to enable hydrometeor clusters to extend across the 0°C level. With these developments we evaluate and improve with our dual strategy the representation of three more key polarimetric signatures pointing to different model deficiencies: (1) Columns of enhanced differential reflectivity ZDR will guide improvements in the freezing process of raindrops, (2) ZDR near the surface is the key sign for a better parameterization of raindrop size distributions, and (3) polarimetric variables in the dendritic growth layer show pathways to improve and extend the representation of ice microphysical processes (e.g. secondary ice production) in ICON. Finally, we will exploit polarimetry-derived information for indirect data assimilation in ICON. Based on the developments of the project, we assimilate ZDR-column objects and/ or the partitioning ratios derived from our new HMC, most likely in the form of categorical ranking information.