A Doppler Radar Climatology of Updraft Proxy Characteristics in Supercells

超级单体上升气流代理特征的多普勒雷达气候学

• 批准号: 2303590
• 负责人: Michael French
• 金额: $ 44.1万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-15 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2303590&HistoricalAwards=false
• 关键词: Doppler; Radar; Climatology; Updraft; Proxy

The project concerns the use of weather radar signatures to estimate the size and tilt of an important storm feature, the storm updraft, within severe thunderstorms. The updraft is an area of rapidly rising air that is transported aloft to form clouds and eventually precipitation. The updraft contributes to every hazard that a storm produces, notably large hail and tornadoes. Past work has provided evidence that larger storm updrafts produce stronger tornadoes and larger hail compared to storms with smaller updrafts. In addition, studies have hinted that storm updrafts that are vertically upright, as opposed to tilted, are also more likely to produce tornadoes. Unfortunately, it is difficult to directly observe and measure characteristics of the storm updraft. However, upgrades performed to the U.S. radar network have introduced new options to track features that serve as a proxy for the updraft. In this project, the researchers use the size and tilt of this radar feature as an estimate for those same characteristics in the updraft in more than 100 actual storm cases to better determine how closely linked updraft size and tilt are to tornado and hail occurrence. The researchers also will determine if the weather conditions feeding into the storm are linked to the size and tilt of the updraft. The project objectives ultimately aim to provide forecasters with new tools that may help them alert the public to storms that are about to produce strong tornadoes and/or very large hail.The storm type being studied is the supercell thunderstorm, which generally produces the strongest tornadoes and largest hail. To estimate the size and tilt of supercell updrafts, the researchers use a novel algorithm that automates detection and area of a dual-pol radar signature, the ZDR column, which forms when an updraft lofts rain and small hail above the freezing level. Those data will be used in tandem with traditional radar analyses to identify links between updraft proxy characteristics, the near-storm environment, and hazard production in large numbers of supercell cases. Specifically, this project seeks to (i) determine a firm link between midlevel updraft area, low-level updraft area, and tornado and large hail occurrence, (ii) quantify the degree to which updraft vertical alignment is necessary for tornado production, (iii) the near-storm environmental controls, if they exist, on both updraft size and alignment, and (iv) combine the results from (i) and (ii) with data of another dual-pol radar signature, the ZDR-KDP separation vector, to optimize known predictors of tornado formation and peak tornado intensity for possible operational use. In addition, depending on project results, the ability to accurately assess these characteristics and their potential use in nowcasting of hazardous weather will be explored.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目涉及使用天气雷达特征来估计强雷暴中重要风暴特征（风暴上升气流）的大小和倾斜度。上升气流是空气快速上升的区域，被输送到高处形成云并最终形成降水。上升气流会导致风暴产生的各种危害，特别是大冰雹和龙卷风。过去的工作提供的证据表明，与较小上升气流的风暴相比，较大的风暴上升气流会产生更强的龙卷风和更大的冰雹。此外，研究暗示，垂直直立的风暴上升气流（而不是倾斜的）也更有可能产生龙卷风。不幸的是，直接观察和测量风暴上升气流的特征是很困难的。然而，对美国雷达网络进行的升级引入了新的选项来跟踪作为上升气流代理的特征。在该项目中，研究人员使用该雷达特征的大小和倾斜度来估计 100 多个实际风暴案例中上升气流的相同特征，以更好地确定上升气流大小和倾斜度与龙卷风和冰雹发生的密切关系。研究人员还将确定引发风暴的天气条件是否与上升气流的大小和倾斜有关。该项目的最终目标是为预报员提供新工具，帮助他们提醒公众注意即将产生强烈龙卷风和/或超大冰雹的风暴。正在研究的风暴类型是超级单体雷暴，通常会产生最强的龙卷风和最大的冰雹。为了估计超级单元上升气流的大小和倾斜度，研究人员使用了一种新颖的算法，可以自动检测和确定双极化雷达特征的面积，即 ZDR 柱，当上升气流在冰点以上下雨和小冰雹时就会形成 ZDR 柱。这些数据将与传统雷达分析结合使用，以确定大量超级单体案例中上升气流代理特征、近风暴环境和灾害产生之间的联系。具体来说，该项目旨在 (i) 确定中层上升气流区、低层上升气流区与龙卷风和大冰雹发生之间的牢固联系，(ii) 量化龙卷风产生所需的上升气流垂直对准程度，(iii) ) 近风暴环境控制（如果存在）对上升气流大小和对准的影响，以及 (iv) 将 (i) 和 (ii) 的结果与另一个双极雷达特征数据（ZDR-KDP 分离矢量）相结合,优化龙卷风形成和龙卷风峰值强度的已知预测因子，以供可能的操作使用。此外，根据项目结果，将探索准确评估这些特征的能力及其在危险天气临近预报中的潜在用途。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的评估进行评估，被认为值得支持。影响审查标准。