Identifying the Physical Drivers and Radar Signatures of Fire-Generated Tornadic Vortices

野火会产生自身的恶劣天气，包括嵌入野火羽流的龙卷风和雷暴。这些火灾产生的极端情况威胁着消防员和公共安全，但人们对它们知之甚少，而且往往是不可预测的。为了填补这一知识空白，研究人员建议通过从气象雷达和卫星数据中确定导致火灾龙卷风和雷暴的共同因素，来了解火灾产生的极端天气。该项目还将让公众参与到野火科学中来，比如在中学课堂上开设以火灾天气为重点的课程，并开展一项公民科学社交媒体活动，收集从野火羽流中“降雨”而下的灰烬和碎片的照片。公众收集的众包数据将有助于提高我们对野火羽流的理解，以便更好地记录射向天空的物质的大小和形状。几十年来，利用雷达和卫星观测成功地发布了挽救生命的对流恶劣天气（例如，严重雷暴）警报，这促使了这项拟议的工作。对于火产生的龙卷风（FGTV）和火积雨云（pyroCb），这些工具显示出显著的潜力，但尚未完全实现。为了充分实现这一潜力，需要新的物理和概念模型来解释野火环境的雷达和卫星观测。为了开发这些模型，研究人员将测试一系列假设，这些假设旨在分离与FGTV发展相关的雷达和卫星观测到的火焰和羽流过程的共同特征。这些假设是基于初步观察，证明FGTV产生的火灾通常表现为：(1)弯曲和分叉的羽流具有嵌入和脱落的旋涡，(2)火灾周围的流动分裂和流动逆转的不对称性，有利于一种旋涡旋转（即气旋与反气旋），以及(3)pyroCb起始与旋涡增强同时发生。在分离FGTV火灾的共同属性和观察到的特征时，研究小组的目标是为FGTV形成建立概念模型。这些概念模型将促进救生预警，加强对野火利益相关者的决策支持，从而提供直接的社会效益。作为该提案的一部分，社区参与和教育将包括：(a)将雷达观测与野火羽流落下的灰烬大小和形状的照片记录联系起来的社交媒体公民科学运动，(b)在课堂上的中学学习经验和课程与基于应用程序的数据收集模块相结合，(c)研究生指导和课程开发，以及(d)向公众和野火利益相关者进行宣传。公民科学运动预计每年将有1000名用户，而课堂课程每年将有500多名学生参加。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wildfires can generate their own severe weather, including tornados and thunderstorms embedded in the wildfire plume. These fire-generated extremes threaten fire-fighter and public safety yet are poorly understood and often unpredicted. To fill this knowledge gap, the investigators propose to understand fire-generated extreme weather by identifying the common factors contributing fire-generated tornados and thunderstorms from weather radar and satellite data. The project will also engage the public in wildfire science such as developing middle-school in-class lessons focused on fire-generated weather and conducting a citizen-science social-media campaign to collect photographs of the ash and debris that “rain” down from wildfire plumes. The crowd-sourced data collected by the public will help improve our understanding of wildfire plumes for better documenting the size and shape of material lofted into the sky.The proposed work is motivated by decades of success in using radar and satellite observations to issue life-saving warnings for convectional severe weather (e.g., severe thunderstorms). For fire-generated tornadic vortices (FGTV) and pyrocumulonimbus (pyroCb) these same tools show remarkable, yet incompletely realized potential. To fully realize this potential, new physical and conceptual models are required for interpreting radar and satellite observations of the wildfire environment. To develop these models, the investigators will test a sequence of hypotheses designed to isolate the common characteristics of radar and satellite observed fire and plume processes linked to the FGTV development. These hypotheses are based on preliminary observations demonstrating FGTV producing fires often exhibit: (1) bent-over and bifurcating plumes with both embedded and shedding vortices, (2) asymmetries in flow splitting and flow reversal around the fire that favor one sense of vortex rotation (i.e., cyclonic vs. anticyclonic), and (3) pyroCb initiation concurrent with vortex intensification. In isolating the common attributes and observed signatures of FGTV fires, the research team aims to produce conceptual models for FGTV formation. These conceptual models will facilitate life-saving warnings and enhance decision support for wildfire stakeholders, thereby providing an immediate societal benefit. Community engagement and education as part of this proposal will include: (a) social-media citizen-science campaign linking radar observations with photographic documentation of size and shape of ash falling from wildfire plumes, (b) in-classroom middle school learning experiences and curriculum coupled with an app-based data collection module, (c) graduate student mentoring and curriculum development, and (d) outreach to the public and wildfire stakeholders. The citizen-science campaign is expected to reach 1000s of users annually, and the in-classroom program upwards of 500 students per year.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.