Multi-Scale Experimental Investigations of Extreme Plasma Density Depletions in the Polar Ionosphere

极地电离层极端等离子体密度损耗的多尺度实验研究

基本信息

批准号：
2022159
负责人：
Geoffrey Crowley
金额：
$ 56.03万
依托单位：
ATMOSPHERIC & SPACE TECHNOLOGY RESEARCH ASSOCIATES, L.L.C.
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2022159&HistoricalAwards=false
关键词：
Multi Scale Experimental Investigations Extreme

项目摘要

This project will investigate a phenomenon called ‘polar holes’ in the polar ionosphere, which is a region of atmosphere (80 to 1000 km above sea level) that is highly ionized due to solar radiation, with high concentration of charged particles, i.e. electrons and ions. The polar hole refers to the large reduction of charged particles (called plasma) that appears from time to time in the so-called F-region (150 to 500 km) and is believed to happen more often during the solar minimum when the solar radiation is at its lowest level. The formation of such holes is related to the complex interactions of the charged particles with the electromagnetic field and atmospheric circulation that are unique in the polar region. Understanding the formation and internal structures of the polar holes fills the gap of our understanding of such interactions and helps improve model simulation of the polar ionosphere. The current solar minimum provides a good opportunity to study this phenomenon.This project will experimentally investigate the polar holes and the role of the plasma convection in their formation and evolution. Polar holes are believed to be formed during the periods of the very slow anti-sunward convection, when the plasma is trapped just poleward of the statistical auroral oval in the absence of any ionization sources. At the same time, fast convection with rapid vertical plasma transport has also been associated with the polar hole formation. Combining the multi-point capability of the Advanced Modular Incoherent Scatter Radar (AMISR) located in the northern polar cap, the state of art variational data assimilation tool IDA4D developed at ASTRA, and the convection data from the Super Dual Auroral Radar Network (SuperDARN) array, the role of plasma convection in the polar hole formation will be investigated. The density in the vicinity of the polar holes is thought to be very structured. This study will explore the polar hole internal structure, analyze the gradients that are present inside the polar hole and on its edges, and evaluate their effects on high-frequency radar backscatter. Finally, to improve the predictability of the electron density conditions in polar cap regions, which are most problematic for modeling, a statistical analysis of the polar cap density during the solar minimum conditions will be performed. Variability of the polar cap density will be investigated using IDA4D runs and large amounts of collected radio occultation data from COSMIC I mission in the northern and southern polar regions to find the most problematic time periods where the model parameters and data-derived parameters have the largest differences.The work will improve our knowledge of the plasma depletions in the polar cap during solar minimum conditions. The polar cap during the winter and during the solar minimum is one of the most problematic zones for the ionospheric models used in application areas, such as satellite communications, satellite-based navigation, data links, and space situational awareness. This work will improve the ability to model the electron density in the polar cap region by direct investigation of its lowest extremes and by statistical investigation of its variability. This project will support an early-career female researcher who has a strong track record of outreach activities, including delivering Space Physics lectures for senior people and developing the www.sheisaphysicist.com web space that promotes and cultivates the success of women in physics by publishing stories about the career path of female physicists. When a new interview is published, the website reaches ~2000 independent views, inspiring high-school and undergraduate female students to choose physics as their career path. This will contribute to broadening of participation of underrepresented minorities in STEM fields.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.

该项目将研究极地离子层中称为“极孔”的现象，该现象是大气区域（海拔80至1000 km），该区域由于太阳辐射而高度离子化，具有高浓度的带电颗粒，即电子和离子。极性孔是指在所谓的F-Region（150至500 km）中不时出现的带电颗粒（称为等离子体）的大幅减少，并且据信在太阳辐射处于最低水平时，在太阳最小值期间发生了更频繁的发生。这种孔的形成与电磁颗粒与极地区域独特的电磁场和大气环流的复杂相互作用有关。了解极孔的形成和内部结构填补了我们对这种相互作用的理解的空白，并有助于改善对极性电离层的模型模拟。当前的太阳最小值为研究这种现象提供了一个很好的机会。该项目将实验研究等离子体构建在其形成和进化中的作用。据信，在没有任何电离源的情况下，在非常缓慢的反肺连接期间形成了极孔。同时，与快速垂直等离子体传输的快速连接也与极孔形成有关。结合了位于北极帽的高级模块化散射雷达（AMISR）的多点功能，在ASTRA开发的最先进的变量数据同化工具IDA4D以及超级双极光雷达网络（Superdarn）阵列的构造数据，Polarsma构造的作用将被调查。极孔附近的密度被认为是非常结构化的。这项研究将探索极性孔的内部结构，分析极性孔和边缘内的梯度，并评估它们对高频雷达反向散射的影响。最后，为了提高极性盖区域电子密度条件的可预测性，这对于建模最有问题，将对太阳最小条件下的极性盖密度进行统计分析。极性盖密度的可变性将使用IDA4D运行以及来自北极和南极区域的宇宙I任务收集的大量无线电事件数据进行研究，以找到最有问题的时间段，其中模型参数和数据衍生的参数具有最大的差异。冬季和太阳最小值期间的极性盖是应用领域中使用的电离层模型最有问题的区域之一，例如卫星通信，基于卫星的导航，数据链接和空间情境意识。这项工作将通过直接投资其最低极端和可变性的统计投资来提高极地帽区域中电子密度的模型。该项目将支持一位早期职业女性研究人员，该研究人员拥有良好的宣传活动记录，包括为高级人员提供太空物理讲座以及开发www.sheisaphysics.com网络空间，该网络空间通过出版有关女性物理学家的职业道路来促进和培养妇女在物理学领域的成功。当发布新的采访时，该网站将达到〜2000个独立视图，激发了高中生和本科女学生选择物理学作为职业道路。这将有助于扩大代表性不足的少数群体在STEM领域的参与。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准，被认为值得通过评估来获得支持。