CAREER: Self-consistent and Data-constrained Simulations of the Leader and Return Stroke Processes in Lightning Discharges

职业：闪电放电中先导和回程过程的自洽和数据约束模拟

• 批准号: 2046043
• 负责人: Caitano da Silva
• 金额: $ 52.32万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2046043&HistoricalAwards=false
• 关键词: CAREER; Self; consistent; Data; constrained

Despite lightning being such a common natural phenomenon, a large portion of its fundamental physics remains to be uncovered. Even its most studied element — the return stroke — remains to be fully quantified. A central question in lightning physics has to do with how the widely-observed asymmetry in positive- and negative-leader propagation maps into the overall contrasting differences between cloud-to-ground (CG) flashes of both positive and negative polarities (leader is the term used to describe the elongation lightning channel before its connection to the ground). One important example is the origin of recoil leaders, which are observed to only retrace the channels of positively-charged leader channels. Recoil leaders in its turn may be the root cause for the asymmetry in stroke multiplicity between positive and negative CGs. Understanding the physics of lightning at a fundamental level is required for quantifying its effects in our planet's atmosphere (e.g., production of nitrogen oxide compounds) and to mitigate its societal impacts (e.g., power transmission and distribution disruptions). Through the development of novel computer models, this project addresses outstanding questions in lightning physics outlined in the second paragraph below. The broader impacts of this project are heavily tied with the educational plan. The backbone of our educational plan is to develop teaching strategies based on the simple idea that a physics instructor can use lightning and thunderstorms — something that any student is familiar with — to introduce complex physics concepts. This project tackles two key problems in lightning physics. Problem 1: When leader channels connect to a ground structure, a strong current surge known as the return stroke travels upward. The most widely-employed type of return stroke model assumes that the wave propagation velocity and its attenuation with height are free parameters of the model. Despite a few attempts from previous investigation, a detailed characterization of the return stroke dynamics from first-principles remains an open problem. Problem 2: Positive and negative leaders have different propagation mechanisms (different velocities and channel branching rates, and continuous vs. stepped propagation). It has been hypothesized that this polarity asymmetry maps into how differently current cutoff and recoil leader formation takes place in positive and negative CG flashes. However, there is no computational simulation tool available that can fully answer this complicated question. The main goal of this project is to advance the current understand of lightning by introducing two novel physics-based models to describe the main stages of a lightning flash, and address the two problems outlined above: (1) a return stroke model that calculates the velocity of current and optical luminosity waves and their attenuation as they propagate upward towards the cloud, and (2) a stochastic, 3-dimensional model of the leader channel network, which accounts for probabilistic branching and has different propagation mechanisms for positive and negative extremities. The most important advance aimed here is the coupling of these two electrodynamics models with a realistic treatment of the plasma channel's nonlinear resistance.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.

尽管闪电是一种常见的自然现象，但它的大部分基础物理学仍有待揭开，即使是它最受研究的元素——回击——也仍然有待完全量化。闪电物理学的一个核心问题与如何广泛传播有关。 -观察到的正负先导传播的不对称性映射到正极性和负极性的云对地（CG）闪光之间的总体对比差异（先导是用于描述在连​​接到闪电之前的伸长闪电通道的术语）地面）。一个重要的例子是反冲先导的起源，据观察，反冲先导仅沿着带正电荷的先导通道进行回溯，而反冲先导可能是正负 CG 之间中风多重性不对称的根本原因。需要从根本上量化闪电对地球大气的影响（例如，氮氧化物化合物的产生），并通过开发新颖的技术来减轻其社会影响（例如，输电和配电中断）。计算机模型，该项目解决了下面第二段中概述的闪电物理学中的突出问题，该项目的更广泛影响与教育计划密切相关，我们的教育计划的支柱是基于以下简单想法制定教学策略。物理教师可以使用任何学生都熟悉的闪电和雷暴来介绍复杂的物理概念，该项目解决了闪电物理中的两个关键问题：当先导通道连接到接地结构时，会产生称为“强电流浪涌”的电流。返回行程向上移动。广泛使用的回程模型假设波传播速度及其随高度的衰减是模型的自由参数，尽管之前的研究进行了一些尝试，但根据第一原理对回程动力学进行详细表征仍然是一个悬而未决的问题。问题 2：正引导和负引导具有不同的传播机制（不同的速度和通道分支率，以及连续传播与阶梯传播）。人们对这种极性不对称性如何映射到电流截止进行了不同的研究。反冲先导形成发生在正向和负向 CG 闪光中。然而，没有可用的计算模拟工具可以完全回答这个复杂的问题，该项目的主要目标是通过引入两种新颖的物理原理来增进对闪电的当前理解。基于模型来描述闪电的主要阶段，并解决上述两个问题：（1）回程模型，用于计算电流和光光度波的速度及其向上传播到云时的衰减，以及（ 2）随机，先导通道网络的 3 维模型，它解释了概率分支，并且对于正端和负端具有不同的传播机制。这里最重要的进展是将这两个电动力学模型与等离子体通道非线性电阻的实际处理相结合。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Close View of the Lightning Attachment Process Unveils the Streamer Zone Fine Structure

近距离观察闪电附着过程揭示流光区精细结构

• DOI: 10.1029/2022gl101482
• 发表时间: 2022-12-14
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: M. Saba;D. R. D. da Silva;J. Pantuso;C. D. da Silva
• 通讯作者: C. D. da Silva

Data-Driven Simulations of the Lightning Return Stroke Channel Properties

雷电回击通道特性的数据驱动模拟

• DOI: 10.1109/temc.2022.3189590
• 发表时间: 2022-07
• 期刊: IEEE Transactions on Electromagnetic Compatibility
• 影响因子: 2.1
• 作者: Taylor, Michael C.;da Silva, Caitano L.;Walker, T. Daniel;Christian, Hugh J.
• 通讯作者: Christian, Hugh J.

Lightning radiometry in visible and infrared bands

可见光和红外波段的闪电辐射测量

• DOI: 10.1016/j.atmosres.2023.106855
• 发表时间: 2023-09-01
• 期刊: Atmospheric Research
• 影响因子: 5.5
• 作者: Jacob Wemhoner;Lydia Wermer;C. D. da Silva;Patrick Barnett;C. Radosevich;Sonal Patel;H. Edens
• 通讯作者: H. Edens