Collaborative Research: SGER--Measurements of Particle Size and Fall Velocity Distributions within Supercell Thunderstorms

研究人员将开发一个独特的移动的和快速部署的低成本激光风速仪仪器网络，用于在2009年春季"验证龙卷风起源实验2"活动的第一年收集强风暴内的现场微物理数据。 测量结果将与其他VORTEX 2组件协调，以便融合数据源，更全面地检索风暴的近地表浮力、微物理组成和运动学。 强风暴的微物理成分对风暴的演变和行为有着重要的影响，特别是通过控制风暴下方的冷池特征。 虽然极化雷达观测可以提供与风暴微物理特征相关的信息，但近地表环境的微物理特征被认为对龙卷风的形成最重要，即使是移动的极化雷达平台，通常也低于雷达地平线。 微物理学在近地表浮力趋势中起着关键作用，最近的几项研究表明，这可能会调节龙卷风发展的可能性。 因此，需要在下雨的下沉气流中对近地表微物理进行现场测量，以确定冷池浮力特性，并推断与在地表以上收集的偏振雷达观测的关系。该研究将导致更好地了解风暴微物理学，强风暴下的冷池特征和风暴行为之间的关系。这项研究的智力价值来自于与移动的极化雷达协调的强风暴内的新的现场微物理数据收集方法。 将以协作方式同时探索两种光学转速计部署方法，以最大限度地收集数据。有相当大的挑战和危险与严重风暴内的数据采集。这一努力标志着第一次已知的尝试，收集现场近表面测量的粒度分布的网络的disdrometers。 收集的观测结果将使我们能够对强风暴的微物理特征与其行为之间的关系有新的认识，这些关系符合VORTEX 2的几个关键焦点。这项工作的更广泛的影响包括提高了对严重风暴行为的可预测性。 预计这将出现在更好地了解风暴演变对微物理特征的依赖，迄今为止仍然相对未知。 更好地了解严重风暴的行为最终可以导致更及时和准确的警报，可以挽救生命，并允许更多的时间来保护财产。 此外，该项目开发的仪器套件也非常适合应用于其他类型沉淀系统中的粒度分布测量。 风暴尺度数值天气预报模式中使用的微物理参数化的验证也将受益于部分由测量提供的验证数据。粒度分布测量也将有助于移动的雷达校准和衰减度量。 该项目将使研究生有机会参与数据收集工作，作为一项重大实地活动的一部分。

The investigators will develop a unique network of mobile and rapidly deployable low-cost laser disdrometer instruments for the collection of in situ microphysical data within severe storms during the first year of the Verification of the Origins of Tornadoes Experiment 2 (VORTEX2) campaign in spring of 2009. Measurements will be coordinated with other VORTEX2 components enabling fusion of data sources for a more complete retrieval of the near surface buoyancy, microphysical composition and kinematics of the storm. The microphysical composition of severe storms is known to have significant impacts on storm evolution and behavior, particularly by controlling the cold pool characteristics beneath the storm. While polarimetric radar observations can provide information related to the microphysical character of a storm, the microphysics of the near surface environment, believed to be most important for tornadogenesis, is usually below the radar horizon of even mobile polarimetric radar platforms. Microphysics can play a key role in near surface buoyancy tendency which several recent studies have shown may modulate the likelihood of tornado development. As such, in situ measurements of near surface microphysics within rainy downdrafts are needed in order to determine cold pool buoyancy characteristics and to infer relations with polarimetric radar observations collected above the surface. The research will lead to a greater understanding of the relationship between storm microphysics, cold pool characteristics beneath severe storms and storm behavior. The intellectual merit of the research stems from the novel in situ microphysical data collection method within severe storms coordinated with mobile polarimetric radars. Two methods for optical disdrometer deployment will be simultaneously explored in a collaborative approach to maximize data collection. There are considerable challenges and hazards associated with data acquisition within severe storms. This effort marks a first known attempt to collect in situ near surface measurements of particle size distributions by a network of disdrometers. The collected observations will enable new understanding of the relationship between microphysical characteristics of severe storms and their behavior in line with several key foci of the VORTEX2. The Broader impacts of the work include improved predictability of severe storm behavior. This is expected to emerge from a better understanding of storm evolution dependence on microphysical characteristics, which to date remains relatively unknown. Better understanding of severe storm behavior can ultimately lead to more timely and accurate warnings that can save lives and allow additional time to protect property. Further, the developed instrumentation suite for this project will also be quite suitable for application to particle size distribution measurements in other types of precipitating systems. The verification of microphysical parameterizations used in storm-scale numerical weather prediction models also would benefit from verification data provided in part by the measurements. Particle size distribution measurements will also aid in mobile radar calibration and attenuation metrics. This project will enable graduate students opportunities to participate in data collection efforts as part of a major field campaign.