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.

测得的面雨量与雷达观测计算的雨量之间存在严重的不一致。一种建议的改进估计的方法是使用从雷达反射率给出的降雨率关系，其中包括雨滴的形状。由于这些毫米大小的雨滴不断地振荡，人们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。在这项研究中，我们建议使用高速时间序列分析垂直风洞中漂浮的毫米级液滴的形状来实现这一目标。具有特殊意义的是当量直径(DO)在1.1-3 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有显着不同。此外，对于AQUARADAR现场实验(特别观测阶段，SOP)，我们建议部署美因茨·霍达尔大学(全息液滴和气溶胶记录)仪器，用于现场地面测量雨滴和冰雹/冰雹颗粒尺寸分布、空间水星分布和单个水星速度。对于AQUARadar-D的一台微雨雷达(MRR)，可以在SOP期间以这种方式同时进行微物理降水特性和雷达回波的相关测量。