Studies of New Elements for Global Electric Circuit Models

全球电路模型新要素的研究

• 批准号: 0605026
• 负责人: Thomas Marshall
• 金额: $ 29.69万
• 依托单位: University of Mississippi
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605026&HistoricalAwards=false
• 关键词: Studies; New; Elements; Global; Electric

This project develops improved models that incorporate recent experimental data to give a substantially improved understanding of thunderstorms as generators in the Earth's global electric circuit. Part 1 involves developing a spherical geometry model of a realistic thunderstorm embedded in a realistic, conducting atmosphere. The storm is modeled with layers of steady state currents that are adjusted to reproduce typically observed vertical electric field (E) profiles from different storm types. The model is then applied to large mesoscale convective systems (MCSs), to more typical small storms, and to unscreened convective updrafts by using appropriate vertical electric field profiles. The results of Part 1 will show how different types of storms drive different amounts of current between the Earth and the ionosphere in the global circuit. In Part 2 the model is expanded to handle transient currents associated with lightning flashes. The transient current model is applied to MCSs and to small thunderstorms, and the results will be added to those of Part 1. Through this work the relative importance of transient currents in the global circuit will be deduced. Finally, a global scale examination will be undertaken that incorporates these improved estimates of the several 'thunderstorm components' in the circuit, including mesoscale convective systems, small thunderstorms, unscreened convective cores, and above-cloud transients caused by lightning flashes. The relative contribution of each of these components will be estimated.The overall intellectual merit of this project derives from combining all of the proposed modeling results for the contribution of MCSs, small storms, and their associated transients, with estimations of the number and type of thunderstorms occurring simultaneously on the Earth. This synthesis will provide a state-of the-art estimate of the current that is driven in the global circuit by all simultaneous thunderstorms. This new estimate will be compared to the discharging currents that occur in the fair weather portion of the globe. From this, the overall importance of thunderstorms in the global electric circuit and the overall charge on the Earth can be determined. An estimate of the importance of other contributors to the global circuit, such as non-thunderstorm shower clouds, will also be possible.The broader impacts of this project derive partly from the international collaboration that areextended and expanded throughout the studies. The investigators, graduate students, and undergraduate students will conduct the work in close collaboration with established scientists and young scientists, graduate students, and undergraduate students at the Institute for Applied Physics in Russia. The primary Russian collaborators (one of whom is a recent Ph.D. Candidate) and one graduate student will visit the investigators' laboratory in the U.S. for extended periods. This collaboration also involves an integration of theoretical plasma physicists (Russian collaborators) with experimental atmospheric physicists (U.S. investigators). This exchange will lead to new methods of investigation and discovery for both groups. Another broader impact of the project involves the gender diversity of the scientists and students: one of the U.S. investigators and at least one of the U.S. students are female, and women remain an underrepresented group in physics and in atmospheric physics, especially. Mentorship, training, and education of the undergraduate and graduate students involved will enhance their abilities to become independent researchers in this or another field of science. Publication and dissemination of the results will contribute to better understanding of the global electrical circuit, which is intimately tied to global climate through the global thunderstorm activity.

该项目开发了包含最新实验数据的改进模型，以极大地改善对雷暴作为地球全球电路中的发电机的理解。第1部分涉及开发一个嵌入在逼真的传导大气中的真实雷雨的球形几何模型。风暴由多层稳态电流模拟，这些稳态电流被调整以再现来自不同风暴类型的典型观测到的垂直电场(E)轮廓。然后，通过使用适当的垂直电场廓线，将该模式应用于大、中尺度对流系统(MCSs)、更典型的小风暴以及未屏蔽的对流上升气流。第1部分的结果将展示不同类型的风暴如何在全球电路中的地球和电离层之间驱动不同数量的电流。在第二部分中，该模型被扩展以处理与闪电相关的暂态电流。将暂态电流模型应用于MCSs和小雷暴，并将其结果与第一部分的结果相加。通过这项工作，将推导出暂态电流在整体电路中的相对重要性。最后，将进行一次全球尺度的检查，将这些改进后的对环路中几个雷暴分量的估计纳入其中，包括中尺度对流系统、小雷暴、未屏蔽的对流核心和闪电引起的云上瞬变。这个项目的总体智力价值来自于将所有建议的对MCS、小风暴及其相关瞬变的贡献的模拟结果与对地球上同时发生的雷暴的数量和类型的估计相结合。这一综合将提供全球电路中由所有同时发生的雷暴驱动的电流的最新估计。这一新的估计将与地球上天气晴朗的地区出现的放电电流进行比较。由此，可以确定雷暴在全球电路中的总体重要性和地球上的总电荷。对其他因素对全球环流的重要性的估计也是可能的，例如非雷暴阵雨云。这一项目的更广泛影响部分源于在整个研究过程中不断扩大的国际合作。研究人员、研究生和本科生将与俄罗斯应用物理研究所的知名科学家和青年科学家、研究生和本科生密切合作开展这项工作。俄罗斯的主要合作者(其中一人是最近的博士生)和一名研究生将在较长时间内访问美国的研究人员实验室。这种合作还涉及理论等离子体物理学家(俄罗斯合作者)和实验大气物理学家(美国调查人员)的整合。这次交流将为两个群体带来新的调查和发现方法。该项目的另一个更广泛的影响涉及科学家和学生的性别多样性：一名美国调查人员和至少一名美国学生是女性，女性在物理学和大气物理学领域仍然是一个代表性不足的群体。对参与其中的本科生和研究生的指导、培训和教育将增强他们成为这个或另一个科学领域的独立研究人员的能力。结果的出版和传播将有助于更好地了解全球电路，而全球电路通过全球雷暴活动与全球气候密切相关。