Experimental and Numerical Investigations of Spectral Broadening and the Onset of Precipitation in Warm Rain In Cumulus over the Ocean (RICO) Cumuli

“海洋上空积云中的雨”实验将是一项多研究者研究暖雨形成和信风积云性质的实验。在该实验中正在研究的一个假设是，云层中的湍流空气运动增加了云滴之间的碰撞率，从而加速了降雨的形成。这些研究人员将通过对云中液滴位置的空间不均匀性进行测量来参与这项研究。利用这些测量结果，他们将评估这种不均匀性导致降雨形成速度比没有湍流时更快的可能性。独特的仪器将包括一个新的“2D-S”（二维立体）成像探测器，一个更新版本的云粒子成像仪，可以提供关于水凝物空间分布的高分辨率信息，以及一个高分辨率测量遇到的每个液滴位置的仪器。这些仪器有望为以前难以从飞机上测量的数量提供可靠的测量，包括毛毛雨的大小范围和水滴的聚集。如果它们被证明是可靠的，它们有可能有助于许多未来的云微物理过程的研究。特别是2D-S探头，如果它能提供30-200微米液滴尺寸范围的良好记录，就能为所有RICO调查人员的研究目标做出重大贡献，因为这对项目目标至关重要，而且标准仪器测量效果很差。作为该项目的一部分，仪器的开发和测试也可能有利于未来的测量计划。未来几年的分析工作将包括与建模人员合作，以与观察到的特征一致的方式表示云中的微物理过程。

The "Rain in Cumulus over the Oceans" experiment will be a multi-investigator study of warm rain formation and the nature of trade wind Cumulus clouds. One hypothesis being investigated in that experiment is that turbulent air motions in clouds increase the collision rates among cloud droplets and so accelerate the formation of rain. These investigators will participate in that study by contributing measurements of the spatial inhomogeneities in droplet locations in the clouds. Using those measurements, they will evaluate the possibility that such inhomogeneities lead to faster rain formation than would be present without turbulence. Unique instruments will include a new "2D-S" (Two-Dimensional Stereo) imaging probe, an updated version of a cloud particle imager that can provide information on the spatial distribution of hydrometeors with fine resolution, and an instrument that measures the location of each droplet encountered with high resolution. These instruments promise to provide reliable measurements of quantities previously difficult to measure from aircraft, including the drizzle size range and the clustering of droplets. If they are shown to be reliable, they have the potential to contribute to many future studies of microphysical processes in clouds. The 2D-S probe in particular could make a major contribution to research objectives of all RICO investigators if it provides good documentation of the 30-200 micrometer droplet size range because this is of crucial importance to the project objectives and is poorly measured by standard instruments. The instrumentation development and testing that will occur as part of this project may benefit future measurement programs as well. Analysis efforts in subsequent years will include collaboration with modelers to represent microphysical processes in clouds in ways that are consistent with the observed characteristics.