PRAC: Understanding the development and evolution of violent tornadoes in supercell thunderstorms

PRAC：了解超级单体雷暴中猛烈龙卷风的发展和演变

• 批准号: 1614973
• 负责人: Leigh Orf
• 金额: $ 3.84万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1614973&HistoricalAwards=false
• 关键词: PRAC; Understanding; development; evolution; violent

Each year, tornadoes cause millions to billions of dollars of property damage in the United States.Since 1990, an average of 78 U.S. citizens were killed annually by tornadoes. In2011, 553 lost their lives from 59 tornadoes out of 1,690 that occurred that year in 48 states.Despite advances in observational and modeling/computing technology, thebehavior of tornadoes remains a mystery. We are currently unable to predict whether agiven thunderstorm will produce a tornado, much less whether it will be short-lived and weak, orlong-lived and powerful. The proposed work will use Blue Waters to simulate many different violent tornadoes at resolutions in which the tornado is resolved from its genesis through its dissipation.By simulating many storms in different environments, the project hopes to identify the factors involved inthe formation and maintenance of the most devastating tornadoes, as well as learn more about itsstructure and evolution. This work has the potential to improve the forecasting of the most devastatingstorms, ultimately saving lives. Once specific features related to the genesis and maintenance oflong-lived violent tornadoes are identified in simulations on Blue Waters, field researchers can search forsuch features in observed storms. Such features identified on operational weather radar could helpforecasters issue specific, targeted warnings for unusually violent tornadoes. Furthermore, modificationsto the code used in the study, CM1, will be shared with the weather modeling community.In a prior work, the project conducted a breakthrough ultra-high resolution simulation (30 meter grid spacing) on Blue Watersof a long-lived violent tornado spawned from a supercell that was based upon the observed24 May 2011 EF5 tornadic supercell in central Oklahoma. The project proposes to build upon this previous work to explore thesensitivity of tornado morphology in the 24 May 2011 storm to parameters such as cloud microphysics,turbulence parameterization and low-level environmental wind shear. In addition, the project will enable the useof arbitrarily stretched vertical grids in CM1 in order to focus resolution at key vertical levels, suchas near the ground. Moreover, the project will apply surface friction in a physically realistic manner, add functionalityto CM1 that enables the centrifuging of rain and hail in regions of intense rotation, and exploreother storm environments in which violent tornadoes occurred. Finally, the project will add the ability for CM1 tointerpolate restart files from a coarser mesh to a finer mesh, allowing the model to simulate periodsof the storm?s life cycle where extreme resolution is focused on the core of storm.

每年，龙卷风都会在美国造成数百万至数十亿美元的财产损失。自1990年以来，平均每年有78名美国公民死于龙卷风。 2011 年，48 个州发生了 1,690 场龙卷风，其中 59 场龙卷风导致 553 人丧生。尽管观测和建模/计算技术取得了进步，龙卷风的行为仍然是一个谜。我们目前无法预测给定的雷暴是否会产生龙卷风，更不用说它是短暂而微弱的，还是长期而强大的。拟议的工作将使用 Blue Waters 来模拟许多不同的猛烈龙卷风，其中龙卷风从其产生到消散都得到解决。通过模拟不同环境中的许多风暴，该项目希望确定参与龙卷风形成和维持的因素。最具破坏性的龙卷风，并了解更多有关其结构和演变的信息。这项工作有可能改善对最具破坏性风暴的预测，最终挽救生命。一旦在 Blue Waters 的模拟中确定了与长期猛烈龙卷风的发生和维持相关的特定特征，现场研究人员就可以在观测到的风暴中搜索这些特征。运行气象雷达识别的这些特征可以帮助预报员针对异常猛烈的龙卷风发出具体的、有针对性的警告。此外，对研究中使用的代码 CM1 的修改将与天气建模社区共享。 在之前的工作中，该项目对 Blue Waters 的长寿命暴力进行了突破性的超高分辨率模拟（30 米网格间距）。龙卷风由一个超级单体产生，该超级单体基于 2011 年 5 月 24 日在俄克拉荷马州中部观测到的 EF5 龙卷风超级单体。 该项目拟在之前的工作基础上探索 2011 年 5 月 24 日风暴中龙卷风形态对云微物理、湍流参数化和低层环境风切变等参数的敏感性。 此外，该项目将允许在 CM1 中使用任意拉伸的垂直网格，以便将分辨率集中在关键的垂直水平上，例如靠近地面的水平。 此外，该项目将以物理真实的方式应用表面摩擦，为 CM1 添加功能，使雨水和冰雹能够在强烈旋转的区域进行离心，并探索发生猛烈龙卷风的其他风暴环境。 最后，该项目将为 CM1 添加将重新启动文件从较粗的网格插值到较细的网格的功能，从而使模型能够模拟风暴生命周期的各个时期，其中极端分辨率集中在风暴的核心。