CAREER: Coherent Structures in Ionospheric-Thermospheric Flows

检查和比较电离层和热层的流场结构可以告诉我们为什么它们可能在某些时间排列而在其他时间不排列。作为CAREER奖的一部分，PI将把地球空间科学、等离子体动力学和遥感教育整合到不同的背景中。教育活动包括1)通过波音学者学院向地区高中中代表性不足的少数民族开展地球和空间科学宣传；2)通过IIT跨专业项目计划（IPRO）进行跨学科项目学习的本科教育；3) IIT AIAA学生分会高空气球项目本科生科研训练及本科生指导；4)研究生阶段的课程开发；5)多篇博士、硕士论文研究生指导。除了通过出版物、演讲和讲习班向更广泛的科学界传播之外，还将开展这些活动。在物理学的许多领域中，一个共同的问题是物质在运动介质中的运动。近年来，一种被称为拉格朗日相干结构（LCS）的数学技术被用于模拟这些材料如何随时间漂移和传播。LCS代表了非定常流中的材料表面，这些区域以不同的性质演变。无论动力学方程是未知的还是不可解的，LCS都可以作为流中的组织结构，为理解系统相互作用提供新的上下文和框架。LCS分析借鉴了其他学科的最新知识，它处理的是非定常流，一个历史上复杂和不可预测的现象。LCS可以通过提供导致非定常流散的物理过程的证据，帮助我们完善对潜在动力学的理解。虽然LCS已被用于研究风、空气动力流和流体中物质云的运动，但它从未被应用于高层大气。在这项研究中，研究人员将使用LCS来研究沉积在高层大气中的结构（例如，大气烟雾颗粒、与气候变化有关的污染物、空间碎片）的行为。目标是使用LCS来确定中高纬度流场及其时间演变，在扰动条件下检测和跟踪这些结构的能力，以及赤道纬度湍流混合的播种和传播，这些湍流混合会导致小尺度扰动和无线电信号闪烁，影响高频通信和卫星导航。本研究中LCS的成功开发，为今后利用LCS分析赤道地区垂直气流运动奠定了基础。LCS分析可用于理解IT流体中可能导致闪烁的混沌混合，从而更好地进行操作预测。

Examining and comparing the flow field structures of both ionosphere and thermosphere can tell us why they might be aligned at certain times but not at others. As part of this CAREER award, the PI will integrate geospace science, plasma dynamics and remote sensing education to a diverse range of backgrounds. Educational activities include 1) Earth and space science outreach to underrepresented minorities at area high schools through the Boeing Scholars Academy; 2) undergraduate education through interdisciplinary project-based learning via the IIT Interprofessional Projects program (IPRO); 3) undergraduate research training and undergraduate mentoring of the IIT AIAA student chapter high altitude balloon project; 4) curriculum development at the graduate level; 5) graduate mentoring for multiple Ph.D. and M.S. theses. These activities will be undertaken in addition to dissemination efforts via publications, presentations, and workshops to the broader scientific community. A common problem in many areas of physics is the motion of material in a moving medium. In recent years, a mathematical technique called Lagrangian Coherent Structures (LCS) has been used to model how these materials drift and spread with time. LCS represent the material surface in an unsteady flow separating regions that evolve in qualitatively different ways. Whether the dynamical equations are unknown or unsolvable, the LCS can be an organizing structure in the flow that provides a new context and framework for understanding the system interactions. LCS analysis draws upon the latest knowledge in other disciplines, and it treats the unsteady flow, a historically complex and unpredictable phenomenon. LCS can help to refine our understanding of the underlying dynamics, by providing evidence of the physical processes that lead to unsteady flow divergence. Although LCS has been used to study the motion of clouds of material in wind, aerodynamic flows, and fluids, it has never been applied to the upper atmosphere. In this study, the investigators will use LCS to investigate the behavior of structures (e.g., meteoric smoke particles; climate change-related pollutants; space debris) deposited in the upper atmosphere. The goal is to use LCS to determine the mid-to-high-latitude flow fields and their time evolution, the ability to detect and follow these structures during disturbed conditions, and the seeding and propagation of turbulent mixing at equatorial latitudes, which leads to small-scale disturbances and radio signal scintillation that affects HF communications and satellite-based navigation. Successful development of LCS in this study can enable future studies of LCS analyzing the motion of vertical flow in equatorial regions. LCS analysis can be used to understand the chaotic mixing in IT fluid that may cause scintillation, leading to better operational forecasting.