Advanced Comprehensive Analysis of Rain Drop Shapes, Oscillation Modes, and Fall Velocities Using High-Resolution Surface Disdrometers, Polarimetric Radar, and Numerical Models

雨滴落向地面时不会保持恒定的状态。它们可以改变形状、大小和速度。气象雷达可以测量其中的一些方面，但需要依赖于对其他方面的假设。这个项目将把液滴的观测与数值模拟结合起来，为研究人员提供一个更好的想法，了解每种大小的液滴有多少，液滴碰撞时如何相互作用，以及雷达如何观察液滴。该结果将为雷达降水估算提供更好的数据，从而影响洪水预报和水文。该项目还将为学生，下一代科学家提供培训机会。研究小组将把观测分析与数值模型结合起来，以提高雨滴大小、振荡和下降速度的准确性和完整性。对这些量的了解将使我们能够对中强降雨中雨滴振荡的碰撞强迫的重要性作出新的评价。观测和建模也将允许pi创建新的“逐点”散射矩阵和极化雷达观测值的计算。该项目的观测部分将在阿拉巴马大学亨斯维尔校区附近的一个高度仪器化的地点进行。将使用的主要仪器将是气象粒子光谱仪，用于成像和测量小液滴，以及低调的2d视频disdrometer (2DVD)，用于重叠和较大的液滴。建模工作将包括扩展“逐点”散射方法，以包括对称和非对称形状，后者的计算将基于先进的矩量法表面积分方程技术。

Raindrops do not stay in a constant state as they fall towards the surface. They can change shape, size, and speed. Weather radars can measure some of these aspects, but need to rely on assumptions about others. This project will combine observations of droplets with numerical modeling to provide researchers a better idea about how many of each size of drops there are, how the drops interact when they collide, and how the radar views the droplets. The result will be better data for the estimation of precipitation from radars, which impacts flood forecasting and hydrology. The project will also provide training opportunities for students, the next generation of scientists. The research team will combine observational analysis with numerical models in order to increase the accuracy and completeness of rain drop sizes, oscillations, and fall speeds. Knowledge of these quantities will enable a new evaluation of the importance of collisional-forcing of drop oscillation in moderate-to-intense rain rates. The observations and modeling will also allow the PIs to create new "drop-by-drop" calculations of scattering matrices and polarimetric radar observables. The observational part of the project will take place at a highly instrumented site near the University of Alabama-Hunstville campus. The main instruments to be used will be the Meteorological Particle Spectrometer, for imaging and measurement of small drops, and the low-profile 2D-video disdrometer (2DVD) for overlap and larger drops. Modeling work will consist of extending the "drop-by-drop" scattering methodology to include both symmetric and asymmetric shapes, the latter computations to be based on advance method-of-moments surface-integral-equation techniques.