G‐band Differential Absorption Radar with Doppler

我们对大气水循环的了解是我们预测天气和气候的基础。然而，由于大气边界层和云微物理的复杂性，在云的水汽垂直分布和凝结负荷方面存在着严重的差距。这在应对气候变化方面令人强烈关切，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，有人提议使用差分吸收雷达(DAR)来缩小云内水蒸气测量的差距，并首次进行了地面测试测量，作为美国宇航局未来空间飞行任务的替代。DAR在183 GHz水汽线上使用差分吸收，也就是所谓的G波段，这是以前从未用于大气研究的。提出者的理论工作表明，DAR对地面和空中测量也有很大好处。我们特别感兴趣的是北极地区，那里的湿度倒置和混合相云仍然构成强大的挑战。首次在北极的空中平台上应用DAR将使人们能够对水蒸气分布以及混合相云有新的见解，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流星属性，但包括G波段在内的X波段、K波段和W波段的常见组合仍处于起步阶段。因此，我们的目标是研制一台具有全多普勒能力的仪器，首次实现这种地面测量，以加强对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，在不同地区操作地面和机载仪器，并与世界各地的许多团体合作利用这些测量。我们计划在极地5号飞机以及位于斯瓦尔巴特群岛尼奥勒松德的Awipev(阿尔弗雷德·韦格纳极地和海洋研究所和法国极地研究所保罗·埃米尔·维克托)研究站使用新的G波段水汽剖面和北极云雷达，作为跨区域合作研究中心TR172“北极放大”的一部分。这样，该仪器将成为TR172第三阶段的关键组成部分。此外，我们计划将该仪器部署在作为欧洲气溶胶、云和痕量气体研究基础设施(ACTRIS)一部分的Jülich云演变天文台(Joyce)，以调查典型中纬度站点传感器协同的全部好处，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.