Tornadic Storms with Doppler Polarimetric Radar

使用多普勒偏振雷达观测龙卷风

• 批准号: 0532107
• 负责人: Alexander Ryzhkov
• 金额: --
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0532107&HistoricalAwards=false
• 关键词: Tornadic; Storms; Doppler; Polarimetric; Radar

This project explores the role of microphysical processes and precipitation in tornadogenesis using Doppler polarimetric radars. The research capitalizes on the unique multiparameter radar dataset collected for several tornadic storms in central Oklahoma with the National Severe Storms Laboratory's (NSSL) polarimetric prototype of the WSR-88D radar (KOUN), research dual-polarization Cimarron radar, C-band mobile SMART radars, and the KTLX operational WSR-88D radar. More data will be collected over the 3-year period of the study. Comprehensive analysis of all available polarimetric variables, dual-Doppler velocity fields, and Doppler spectra at horizontal and vertical polarizations are being conducted to address three major topics: First, a detailed 3D analyses of the polarimetric signatures for a number of tornadic and nontornadic supercell storms are performed to examine the temporal evolution of polarimetric patterns and their possible relation to tornado occurrence, and to establish the difference between polarimetric signatures in tornadic and nontornadic supercell storms. Attention is focused on the recently discovered surface-based, small-scale polarimetric debris signature (which is very promising for tornado detection) and larger-scale polarimetric patterns aloft as possible tornado precursors.Second, Doppler spectra at orthogonal polarizations are examined in order to evaluate their utility for tornado detection, and for possible discrimination between low-inertia (rain) and high-inertia (hail, debris) scatterers in the radar resolution volume. Comprehensive spectral analysis of radar echoes is possible because of the unique capability of the KOUN WSR-88D radar to record time series data at two orthogonal polarizations at every gate in a full radar coverage area.Third, the observed polarimetric and spectral radar signatures are interpreted using numerical modeling of precipitation development in the presence of strong vertical air motions, wind shear, and vortex circulation. In addition, hydrometeor trajectories in the tornadic storms are examined using the air velocity fields retrieved from a dual-Doppler analysis.The project has broad potential impact in light of the upcoming upgrade of the National Weather Service weather radars to polarimetric ability in the near future. Better tornado detection and prediction as well as possible assimilation of polarimetric radar data into storm-scale numerical models with improved microphysics can lead to improved forecasts of tornadoes. Educational components include participation of the principal investigators in the new Radar and Instrumentation Curriculum at the University of Oklahoma, co-advising across disciplines, and inter-disciplinary research in the funded NSF undergraduate Education (DUE) project.

本项目利用多普勒偏振雷达探索微物理过程和降水在龙卷风形成中的作用。该研究利用了在俄克拉荷马州中部收集的几个龙卷风风暴的独特的多参数雷达数据集与国家严重风暴实验室（NSSL）的WSR-88 D雷达（KOUN），研究双极化西马龙雷达，C波段移动的SMART雷达，和KTLX业务WSR-88 D雷达的偏振原型。将在3年研究期间收集更多数据。正在对所有可用的极化变量、双多普勒速度场和水平和垂直极化的多普勒频谱进行综合分析，以解决三个主要问题：首先，对一些龙卷风和非龙卷风超级单体风暴的偏振特征进行了详细的3D分析，以研究偏振模式的时间演变及其与龙卷风发生的可能关系，并建立龙卷风和非龙卷风超级单体风暴中极化特征之间的差异。注意力集中在最近发现的地面小规模极化碎片特征上（这是非常有前途的龙卷风检测）和大尺度偏振模式高空可能的龙卷风前兆。第二，多普勒频谱在正交偏振检查，以评估其效用的龙卷风检测，并为可能的区分低惯性（雨）和高惯性（冰雹，碎片）散射体的雷达分辨率体积。由于KOUN WSR-88 D雷达能够在整个雷达覆盖区域的每个门记录两个正交极化的时间序列数据，因此可以对雷达回波进行全面的频谱分析。第三，在强垂直空气运动、风切变和涡旋环流的存在下，使用降水发展的数值模拟来解释观测到的极化和频谱雷达特征。此外，水凝物的轨迹在龙卷风风暴检查使用的空气速度场检索从双多普勒analysis.The项目具有广泛的潜在影响，在不久的将来即将升级的国家气象局的天气雷达极化能力。更好地探测和预测龙卷风，以及可能将偏振雷达数据同化为风暴尺度的数值模型，并改进微物理学，可以改善龙卷风的预报。教育部分包括主要研究人员在新的雷达和仪器仪表课程在俄克拉荷马州的大学参与，跨学科的共同建议，并在资助NSF本科教育（DUE）项目的跨学科研究。