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.

尽管闪电是一种自然现象，但其基本物理学的很大一部分仍有待发现。即使是研究量最大的元素 - 回归中风 - 仍有待完全量化。闪电物理学中的一个核心问题与正面和负面领导者传播图中广泛观察的不对称性如何涉及正云到地面（CG）闪光之间的整体对比差异（领导者是用来描述延长灯光在与地面连接之前的术语）。一个重要的例子是后坐力领导者的起源，观察到只能追回带正电荷的领导者通道的通道。后坐力领导者反过来可能是正面和负CG之间卒中多样性中不对称性的根本原因。要量化其在地球大气中的影响（例如，生产氮氧化物化合物）并减轻其社会影响（例如，电力传输和分配破坏），需要了解基本水平的闪电物理学。通过开发新型计算机模型，该项目解决了以下第二段中概述的闪电物理学中的出色问题。该项目的更广泛影响与教育计划紧密相关。我们的教育计划的主干是基于物理教师可以使用闪电和雷暴的简单想法来制定教学策略（任何学生熟悉的东西）来介绍复杂的物理概念。该项目解决了闪电物理学的两个关键问题。问题1：当领导者通道连接到地面结构时，强烈的电流激增将被称为“返回冲程”。最广泛的返回冲程模型类型的类型假设波传播速度及其高度的衰减是模型的自由参数。尽管以前的调查进行了一些尝试，但对第一原理的返回中风动态的详细表征仍然是一个空旷的问题。问题2：正和负领导者具有不同的传播机制（不同的速度和渠道分支速率，以及连续与阶梯传播）。据推测，这种极性不对称图映射到当前截止和后坐力领导者形成如何在正和负CG闪烁中发生。但是，没有可用的计算模拟工具可以完全回答这个复杂的问题。 The main goal of this project is to advance the current understanding 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分支，具有不同的繁殖机制，用于正向和负四肢。这里最重要的进步是将这两个电子模型与血浆通道的非线性抗性的现实处理结合在一起。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响评估标准来评估值得支持。

项目成果

Lightning radiometry in visible and infrared bands

• DOI: 10.1016/j.atmosres.2023.106855
• 发表时间: 2023-09
• 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

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
• 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.

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

• DOI: 10.1029/2022gl101482
• 发表时间: 2022-12
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: M. Saba;D. R. D. da Silva-D.-R.-D.-da-Silva-2196437034;J. Pantuso;C. D. da Silva