Laboratory studies of the form and oscillations towards breakup of falling raindrops in the Mainz Vertical Wind Tunnel and holographic field measurements of microphysical precipitation properties

美因茨垂直风洞中下落雨滴的形式和振荡破碎的实验室研究以及微物理降水特性的全息场测量

• 批准号: 5448375
• 负责人: Professor Dr. Stephan Borrmann
• 金额: --
• 依托单位: Institut für Physik der Atmosphäre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5448375?language=en
• 关键词: Laboratory; studies; form; oscillations; towards

Serious inconsistencies exist between measured areal rainfall and the rainfall as computed from radar observations. One suggested method to improve on the estimation is to use relationships giving rainfall rates from radar reflectivities which include the shape of the raindrops. As those millimeter size raindrops are continuously oscillating, one has to know the accurate dynamic average values of the axis ratios to be able to use them in the reflectivity rainfall rate relationship. In this study we propose to use high speed time series analysis of shapes of millimetre size drops floating in the vertical wind tunnel to achieve this goal. Of special significance are the axis ratios of the drops with equivalent diameters (Do) between 1.1 and 3 mm whose dynamic mean axis ratios are theoretically predicted to be significantly different from those for the equilibrium shape. Further we suggest for the AQUARadar field experiment (Special Observation Phase, SOP) the deployment of the University of Mainz HODAR (Holographic Droplet and Aerosol Recording) instrument for in-situ ground based measurements of rain droplet and graupel/hail grain size distributions, spatial hydrometeor distributions, and individual hydrometeor velocities. In connection with one micro rain radar (MRR) from AQUARadar-D simultaneous and spatially correlated measurements of microphysical precipitation properties and the radar return can be performed this way during SOP.

测量的面积降雨量与雷达观测计算的降雨量之间存在严重不一致。改进估计的一种建议方法是使用雷达反射率给出降雨率的关系，其中包括雨滴的形状。由于这些毫米大小的雨滴不断振荡，因此必须知道轴比的准确动态平均值，才能在反射率降雨率关系中使用它们。在本研究中，我们建议对垂直风洞中漂浮的毫米尺寸液滴的形状进行高速时间序列分析来实现这一目标。特别重要的是等效直径 (Do) 在 1.1 至 3 mm 之间的液滴的轴比，理论上预测其动态平均轴比与平衡形状的轴比显着不同。此外，我们建议在 AQUARadar 现场实验（特别观测阶段，SOP）中部署美因茨大学 HODAR（全息液滴和气溶胶记录）仪器，用于雨滴和霰/冰雹颗粒尺寸分布、空间分布的原位地面测量。水凝物分布和单个水凝物速度。结合 AQUARadar-D 的微雨雷达 (MRR)，可以在 SOP 期间以这种方式对微物理降水特性和雷达回波进行同步和空间相关测量。