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

雨滴在落到地表时不会保持恒定的状态。它们可以改变形状、大小和速度。天气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。该项目将把对液滴的观察与数值建模结合起来，让研究人员更好地了解每种大小的液滴有多少，液滴碰撞时如何相互作用，以及雷达如何查看液滴。其结果将为雷达估测降水提供更好的数据，从而对洪水预报和水文学产生影响。该项目还将为学生，即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重新评估在中到强降雨率下雨滴振荡的碰撞强迫的重要性。观测和建模还将允许PI创建新的散射矩阵和极化雷达观测值的“逐点”计算。该项目的观测部分将在阿拉巴马大学亨斯特维尔分校附近的一个高度仪器化的地点进行。将使用的主要仪器是用于成像和测量小液滴的气象粒子光谱仪，以及用于重叠和较大液滴的低轮廓2D视频圆盘仪(2DVD)。建模工作将包括扩展“逐滴”散射方法，以包括对称形状和非对称形状，后一种计算将基于先进的矩方法表面积分方程式技术。

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.