Collaborative Research: Anomalous Plasma Cooling in the Topside Ionosphere During Solar Eclipses

合作研究：日食期间顶部电离层的异常等离子体冷却

• 批准号: 1929866
• 负责人: Marc Hairston
• 金额: $ 15.55万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1929866&HistoricalAwards=false
• 关键词: Collaborative; Research; Anomalous; Plasma; Cooling

Previous observations during the 2017 solar eclipse in the weakly ionized portion of the upper atmosphere (the ionosphere) revealed a surprising result. Rather than the expected smooth response to the Moon's shadow, the electron and ion temperatures observed by two satellites traversing the topside ionosphere at 850 km in altitude showed complex and sporadic jumps between regions of cooler plasma and regions where the temperatures were nominal. This project will investigate these unexpected plasma temperature modulations by conducting a thorough analysis of the plasma observations (temperatures, density, flows) for this and other past eclipse events. This will provide important information about how the ionosphere responds to the transient changes in the illumination drivers. Knowledge of these responses is important since solar illumination is a key driver of fundamental processes of ionization and structuring. Radio propagation through the ionosphere depends on how much ionization and structuring occurs, and solar eclipses provide a controlled and quantifiable way to learn more about both positive and adverse effects of the ionosphere on global networks that use radio frequencies, for example the Global Navigation Satellite System. This project will provide detailed characterization of the ionospheric plasma anomalies during solar eclipses using Defense Meteorological Satellite Program measurements of the plasma density, electron and ion temperatures, and plasma transport. It will also provide identification and characterization of mutual relationship between the irregular solar source regions and consequential ionospheric transient modulation. Finally, the project will identify the physical mechanisms, controlling parameters, and limiting cases of the anomalous flows and temperatures. The ultimate goal of this work is to obtain a better understanding of how short-term changes in the illumination of the dayside ionosphere can produce non-uniform responses in the ionospheric density, temperature, and drifts.This project will contribute to the development of a highly-skilled workforce by supporting a graduate student at Boston University.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.

之前在 2017 年日食期间对高层大气弱电离部分（电离层）的观测揭示了一个令人惊讶的结果。与预期的对月球阴影的平滑响应不同，两颗穿越高度为 850 公里的上部电离层的卫星观测到的电子和离子温度显示出较冷等离子体区域和标称温度区域之间存在复杂且零星的跳跃。该项目将通过对此次日食事件和其他过去日食事件的等离子体观测结果（温度、密度、流量）进行彻底分析，来研究这些意外的等离子体温度调制。这将提供有关电离层如何响应照明驱动器瞬态变化的重要信息。了解这些反应非常重要，因为太阳光照是电离和结构化基本过程的关键驱动因素。通过电离层的无线电传播取决于发生电离和结构化的程度，日食提供了一种受控且可量化的方法，可以更多地了解电离层对使用无线电频率的全球网络（例如全球导航卫星系统）的积极和不利影响。该项目将利用国防气象卫星计划对等离子体密度、电子和离子温度以及等离子体传输的测量，提供日食期间电离层等离子体异常的详细特征。它还将提供不规则太阳源区域和随之而来的电离层瞬变调制之间相互关系的识别和表征。最后，该项目将确定异常流量和温度的物理机制、控制参数以及限制情况。这项工作的最终目标是更好地了解白天电离层照明的短期变化如何在电离层密度、温度和漂移方面产生不均匀的响应。该项目将有助于开发通过支持波士顿大学的研究生培养高技能劳动力。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。