CEDAR: Understanding the Loss of Energetic Electrons from the Radiation Belts Using Remote Sensing with Multi-point Riometer Measurements and Satellite In Situ Measurements

CEDAR：利用多点测厚仪测量和卫星原位测量遥感了解辐射带高能电子的损失

• 批准号: 1243183
• 负责人: Yuri Shprits
• 金额: $ 16.42万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1243183&HistoricalAwards=false
• 关键词: CEDAR; Understanding; Loss; Energetic; Electrons

The investigators will use multi-point riometer measurements in conjunction with in-situ satellite data, to improve understanding of the precipitation of energetic electrons into the ionosphere from their magnetospheric origins. Energetic electrons in the 10's of kilo-electron volt (KeV) range precipitate to the upper D- and lower E region ionosphere, and are responsible for enhanced ionization. This same particle population is important in the inner magnetosphere, as it provides a source of waves, and acts as a seed population for relativistic electrons in the radiation belts. In situ observations of plasma populations and waves are usually limited to a single point, which complicates temporal and spatial analysis. Also, the lifespan of satellite missions is often limited to several years, which does not allow the inference of long-term climatology of magnetospheric conditions and solar cycle dependencies. Multi-point remote sensing of the ionospheric plasma conditions can provide a global view of the ionospheric and magnetospheric conditions, and the coupling between magnetospheric and ionospheric phenomena can be examined on time-scales that allow comprehensive statistical analysis. The investigators will inter-calibrate riometers with satellite measurements of precipitating fluxes and also compare to variations in the trapped electron population in the equatorial plane. Comparison with in-situ observations of precipitating fluxes will show which energy electrons can be measured by riometers and allow development of maps of latitudinal and magnetic local time (MLT) distributions of precipitation. The team will also study how precipitation depends on the solar wind conditions and geomagnetic indexes. Comparison with trapped population measurements from satellites will quantify the fraction of the loss to the atmosphere vs loss to the outer boundary of trapping and the outward transport. Long-term riometer measurements, which are correlated with fluxes of precipitating energetic electrons, can be used in the future as a proxy for magnetospheric wave activity. Electron precipitation can also modify ionospheric conductivity, which will influence magnetosphere-ionosphere coupling. This study supports the Van Allen Probe mission by demonstrating how remote sensing of ionospheric precipitation can help scientists understand processes in the magnetosphere and radiation belts. The results of the study will advance knowledge of magnetosphere-ionosphere coupling, which is important to provide better quality conductance estimates in the E-region ionosphere. Additionally, the energetic electrons in the 10's of keV range act as a seed population for relativistic electrons, which may damage satellite systems and hardware. In addition, the precipitation of energetic electrons directly influences the upper atmospheric chemistry, and represents a link between solar and magnetospheric activity, and climate.

研究人员将结合现场卫星数据使用多点测热仪测量，以提高对高能电子从磁层起源进入电离层的沉淀的理解。千电子伏特（KeV）量级的高能电子沉淀到电离层的上、下两个区域，并对电离层的增强起作用。同样的粒子群在内磁层中很重要，因为它提供了波的来源，并作为辐射带中相对论性电子的种子群。等离子体种群和波的现场观测通常仅限于一个点，这使时空分析变得复杂。此外，卫星任务的寿命通常被限制在几年，因此无法推断磁层条件的长期气候学和太阳周期的依赖关系。电离层等离子体条件的多点遥感可以提供电离层和磁层条件的全局视图，并且可以在时间尺度上检查磁层和电离层现象之间的耦合，以便进行全面的统计分析。研究人员将用卫星测量的降水通量对流速计进行校准，并比较赤道平面上捕获电子数量的变化。与降水通量的现场观测相比较，将显示出哪些能量电子可以用流速计测量，并允许绘制降水的纬向和磁地方时（MLT）分布图。该小组还将研究降水如何取决于太阳风条件和地磁指数。与卫星捕获的种群测量值进行比较，将量化大气损失与捕获和向外迁移的外边界损失的比例。与沉淀的高能电子的通量相关的长期里程计测量，可以在未来用作磁层波活动的代理。电子沉淀还可以改变电离层电导率，从而影响磁层-电离层耦合。这项研究通过展示电离层降水的遥感如何帮助科学家了解磁层和辐射带的过程来支持范艾伦探测器的任务。该研究结果将促进对磁层-电离层耦合的认识，这对于提供更优质的e区电离层电导估计非常重要。此外，10 keV范围内的高能电子充当相对论性电子的种子种群，这可能会损坏卫星系统和硬件。此外，高能电子的沉淀直接影响高层大气化学，并代表了太阳和磁层活动与气候之间的联系。