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

调查人员将使用多点riometer测量结合现场卫星数据，以提高对高能电子从其磁层起源沉淀到电离层的理解。 高能电子在几十千电子伏（KeV）范围内沉淀到D区和E区电离层的上部，并负责增强电离。同样的粒子群在内磁层中也很重要，因为它提供了波的来源，并作为辐射带中相对论电子的种子群。等离子体群和波的原位观测通常限于单个点，这使得时间和空间分析复杂化。此外，卫星飞行任务的寿命往往限于几年，这不允许推断磁层条件和太阳周期依赖性的长期气候学。 对电离层等离子体状况进行多点遥感可以提供电离层和磁层状况的全球视图，并且可以在允许进行全面统计分析的时间尺度上审查磁层和电离层现象之间的耦合。研究人员将用卫星测量的降水通量相互校准riometers，并将其与赤道平面上捕获的电子总数的变化进行比较。与现场观测的降水通量的比较将显示哪些能量的电子可以测量riometers，并允许开发地图的纬度和磁性当地时间（MLT）的降水分布。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，将量化损失到大气中的比例与损失到捕获和向外传输的外边界的比例。长期riometer测量，这是与沉淀高能电子通量，可在未来用作磁层波活动的代理。电子沉降还可以改变电离层电导率，从而影响磁层-电离层耦合。这项研究支持货车艾伦探测器使命，演示电离层降水遥感如何帮助科学家了解磁层和辐射带的过程。 这项研究的结果将增进对磁层-电离层耦合的了解，这对于提供E区电离层更高质量的电导估计十分重要。此外，在几十keV范围内的高能电子充当相对论电子的种子种群，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。

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.