Analysis and Observations of Particle Size Distribution in Supercell Thunderstorms

超级单体雷暴中粒径分布的分析与观测

• 批准号: 0969172
• 负责人: Katja Friedrich
• 金额: $ 36.34万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-15 至 2014-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0969172&HistoricalAwards=false
• 关键词: Analysis; Observations; Particle; Size; Distribution

Supercell-type thunderstorms, which embody a complex arrangement of long-lasting rotating updrafts and intense downdrafts, are known to be responsible for generating most intense tornadoes. However, considerable uncertainty exists regarding mechanisms culminating in the actual focus and downward extension of stormscale rotation in the form of a damaging tornadic vortex. Some working hypotheses link this process to the strength, thermodynamic stability (temperature) and spatial configuration of downdrafts in the lowest reaches of these storms, which are in-turn dependent on rates of evaporative cooling influenced by the type and size distributions of falling hydrometeors (chiefly rain and hail.) Rigorous attempts have not yet been made to investigate the range of these microphysical precipitation characteristics beneath supercell thunderstorms. The overarching goal of this project is to i) deploy multiple mobile disdrometers (instruments that measure the characteristic sizes and fallspeeds of precipitation particles) beneath supercell thunderstorms during the second Verification of the Origins of Rotation in Tornadoes EXperiment (VORTEX2; a field program conducted over the central United States known as "tornado alley") in Spring 2010, ii) conduct a comprehensive analysis of both existing and newly-obtained disdrometer observations to determine microphysical characteristics in tornadic compared to nontornadic supercell thunderstorms, and iii) relate these results to contemporaneous high-resolution polarimetric Doppler radar observations. Both disdrometers and polarimetric Doppler radar can detect (or in the case of radar, infer) the size distributions of falling hydrometeors. While preliminary analyses have provided some insights about hydrometeor distributions and their impacts on evolution of supercell storm features, a comprehensive analysis of a number of cases using well-placed high-resolution measurements has yet to be conducted and will be achieved in the course of this work.Intellectual Merit: This project will augment our knowledge about microphysical processes within supercell thunderstorms and may lead to improved short-term forecasts and warnings of life-threatening severe weather. Since VORTEX2 hosts the largest number of polarimetric Doppler radars to ever monitor the full lifecycle of supercell thunderstorms, this experiment is an ideal laboratory to address these scientific questions. At present, the lack of skill in forecasting and understanding microphysical processes is largely due to both the inadequate representation of microphysical processes and the lack of measurements. This mobile deployment of disdrometers in VORTEX2 will provide by far the most comprehensive dataset of disdrometer and radar observations and analysis in supercell thunderstorms ever collected. Broader Impact: The improvement of short-term forecasts and warnings of severe weather is strongly linked to the representation and understanding of the microphysical processes, which will be substantially extended by this work. Results will be shared with the modeling community and integrated with other, existing VORTEX2 data sets. Results will also be disseminated through presentations at conferences, seminars, and workshops as well as through publications in relevant professional journals. Additional Broader Impacts will come through direct involvement of graduate students in collection and analysis of field datasets, as well as through enhanced classroom education at both undergraduate and graduate levels.

众所周知，超持续的旋转上升气流和强烈的下降气流的复杂排列的超级电池型雷暴是造成最激烈的龙卷风的原因。 然而，对于以破坏性龙卷风涡流的形式，在实际焦点和暴风雨旋转的下降的机制方面存在很大的不确定性。 一些有效的假设将此过程与强度，热力学稳定性（温度）和在这些风暴最低范围内的下降气流的空间配置联系起来，这些风暴的最低范围依赖于蒸发冷却速率受到蒸发速度的影响，这些蒸发率受到降水量的类型和尺寸分布的影响（主要是降雨和冰雹），这些范围尚未引起降雨的特征。雷暴。 该项目的总体目标是i）在超级电池雷暴之下部署多个移动调节仪（测量降水颗粒的特征大小和降水量的仪器），这是在第二次验证龙卷风旋转起源的第二次验证龙卷风实验中的旋转起源（Vortex2; Vortex2; Vortex2; Vortex2; Vortex2; Vortex2; Vortex; vortex; vortex; spristion Anally and Anally in II sprist in II ini ii springs in II in II spring in II in II in II）均在Springle and springs in in II），与非龙族超级细胞雷暴相比，新近验证的曲计观测值以确定龙卷风中的微物理特征，iii）将这些结果与同时的高分辨率极化多普勒雷达观测值联系起来。 拆卸仪和偏光多普勒雷达都可以检测（或在雷达，推断）降水器的尺寸分布。 虽然初步分析提供了一些有关水热晶体分布及其对超级风暴特征进化的影响的见解，但对许多案例进行了对许多情况的全面分析，使用良好位置的高分辨率测量值尚未进行，并且将在这项工作中实现。在这项工作中，这项项目将增强我们对超级物理学的知识，并可能会导致超级物理学和超级物理学的经历，并构成了超级物理学的经历。警告威胁生命的恶劣天气。 由于Vortex2拥有最大数量的极化多普勒雷达，以监测超级雷暴的完整生命周期，因此该实验是解决这些科学问题的理想实验室。 目前，缺乏预测和理解微物理过程的技能很大程度上是由于微物理过程的表示不足和缺乏测量。 Vortex2中的调解仪的移动部署将提供迄今为止最全面的径向计和雷达观测值的数据集以及有史以来超级电池雷暴中的分析。更广泛的影响：改善短期预测和对恶劣天气的警告与对微物理过程的表示和理解密切相关，这项工作将大大扩展这项工作。 结果将与建模社区共享，并与其他现有的Vortex2数据集集成。 结果还将通过在会议，研讨会和研讨会上的演讲以及相关专业期刊的出版物中传播。 通过直接参与研究生的收集和分析数据集的收集和分析，以及在本科和研究生水平的增强课堂教育，将产生更广泛的影响。