G‐band Differential Absorption Radar with Doppler

我们对大气水循环的理解对于我们预测天气和气候的能力至关重要。然而，由于大气边界层和云微物理的复杂性，在垂直水汽分布和云凝结水负荷方面存在严重的差距。这在应对气候变化方面引起强烈关注，特别是在北极或其他沙漠地区等观测较少的敏感地区。最近，有人提出用差分吸收雷达（DAR）来弥补云中水汽测量的差距，并进行了第一次地面试验测量，作为美国航天局未来星载使命的替代。DAR使用183 GHz水蒸气线的差分吸收，即所谓的G波段，该波段以前未用于大气研究。提议者的理论工作表明，DAR对于地面和空中测量也有很大好处。我们特别感兴趣的是北极，那里的逆温和混合相云仍然构成巨大的挑战。在北极首次将DAR应用于机载平台，将使人们能够对水汽分布以及混合相云有新的认识，特别是与不同频率的雷达相结合。多频雷达测量能够揭示不同的水凝物特性，但包括G波段到通常的X、K和W波段的组合仍处于起步阶段。因此，我们的目标是一个仪器，充分多普勒能力，使第一次这样的地面测量，以提高云微物理过程的理解。微波遥感是科隆大学的一项关键专长，它开发了新技术，在各区域使用地面和空中仪器，并与世界各地的许多团体合作利用测量方法。我们计划在Polar 5飞机上和位于斯瓦尔巴群岛Ny-埃勒松的AWIPEV（阿尔弗雷德·韦格纳极地和海洋研究所（AWI）和法国极地研究所保罗·埃米尔维克托（IPEV））研究站使用新的G波段水汽剖面和北极云雷达（GRaWAC）仪器，作为跨区域合作研究中心TR 172“北极放大”的一部分。通过这种方式，仪器将成为TR 172第三阶段的关键组件。此外，我们计划在欧洲气溶胶、云和痕量气体研究基础设施的于利希云演化观测站（JOYCE）部署该仪器，以研究传感器协同作用在典型中纬度站点的全部好处，并以这种方式为下一代地面监测系统做好准备。

Our understanding of the atmospheric water cycle is fundamental for our ability to predict weather and climate. However, due to the complex nature in particular of the atmospheric boundary layer and cloud microphysics severe gaps about the vertical water vapor distribution and the condensate load of clouds exist. This is of strong concern in respect to the response to climate change especially in sensitive areas with few observations such as the Arctic or other desert regions. Recently differential absorption radar (DAR) has been proposed to close the gap on in-cloud water vapor measurements and first ground-based test measurements were performed as proxy for a future space-borne mission by NASA. DAR uses the differential absorption at the 183 GHz water vapor line, the so-called G-band, which has previously not been used for atmospheric research. Theoretical work by the proposers shows the large benefit of DAR also for ground-based and airborne measurements. Our particular interest is in the Arctic where moisture inversions and mixed phase clouds are still posing strong challenges. Applying DAR on an airborne platform for the first time in the Arctic will enable new insights into water vapor distribution but also on mixed-phase clouds especially in combination with radar at different frequencies. Multi-frequency radar measurements are able to reveal different hydrometeor properties but including G-band to the usual combination of X-, K-, and W- band is still in its infancy. Therefore, we aim for an instrument with full Doppler capability enabling for the first time such ground-based measurements to enhance the understanding of cloud microphysical processes. Microwave remote sensing is a key expertise at the University of Cologne having developed new techniques, operating ground- and airborne instruments in various regions and exploiting the measurements also in cooperation with many groups worldwide. We plan to use the new G-band Radar for Water vapor profiling and Arctic Clouds (GRaWAC) instrument on the Polar 5 aircraft and at the AWIPEV (Alfred Wegener Institute for Polar and Marine Research (AWI) and the French Polar Institute Paul Emile Victor (IPEV)) research station at Ny-Ålesund, Svalbard, as part of the Transregional Collaborative Research Centre TR172 “Arctic Amplification”. In this way the instrument shall become a key component for the third phase of TR172. Furthermore, we plan to deploy the instrument at the Jülich ObservatorY for Cloud Evolution (JOYCE) being part of the European Aerosol, Clouds and Trace gases Research Infrastructure (ACTRIS) to investigate the full benefit of sensor synergy at a typical mid-latitude site and in this way prepare for the next generation of ground-based monitoring systems.