Collaborative Research: Energetic Particle Precipitation Mechanisms in the Inner Magnetosphere: Van Allen Probes and Incoherent Scatter Radar Coordinated Measurements

这个项目将研究地球磁场中的带电粒子在大气层外和大气层中穿行的机制。确定这些机制对于理解近地环境的各个层是如何耦合的非常重要。了解中性和带电大气对于了解空间天气事件发生的背景已经变得越来越重要。来自国家科学基金会支持的设施，如先进模块化非相干散射雷达（AMISR）的数据将与航天器数据一起进行分析。该奖项还将资助两名博士后研究人员。目前的粒子沉淀理论假设，磁层中的高能粒子由于与地磁赤道或附近的波相互作用，经过俯角散射进入损耗锥后，沉淀到大气中。然而，多个候选波对粒子俯仰角分布影响的实验验证尚未得到明确的建立。该项目汇集了电离层电离的高度分辨测量，内磁层俯角散射的原位测量，以及多学科专业知识，以实现可能涉及电子沉淀机制的所有波模式的封闭。范艾伦探测器对辐射带（或环电流）中的粒子和波的测量和Poker平面非相干散射雷达（PFISR）对在范艾伦探测器通量管脚点附近沉降到电离层的粒子的测量在时间上一致的实例将被确定。利用拟线性扩散方程计算了俯仰角散射的候选波所产生的损失锥分布函数。在几赫兹到几千赫的频率范围内，由电场和磁场产生的电子相空间分布的变化将通过应用加州大学洛杉矶分校的全扩散代码来量化范艾伦探针的粒子和场测量。最后，将范艾伦探测器数据计算的损失锥分布与PFISR直接测量的电离分布在大气中产生的电离分布进行比较。

This project will examine the mechanisms by which charged particles in Earth's magnetic field travel both out of and through the atmosphere. Identifying these mechanisms is important for understanding how the various layers of the near-Earth environment are coupled. Understanding the neutral and charged atmosphere has become of increasing interest for understanding the background in which space weather events play. Data from NSF supported facilities such as the Advanced Modular Incoherent Scatter Radar (AMISR) will be analyzed in conjunction with space craft data. This award will also fund two postdoctoral researchers.Current particle precipitation theories assume that energetic particles in the magnetosphere precipitate into the atmosphere after undergoing pitch-angle scattering into the loss cone due to interactions with waves at or near the geomagnetic equator. However, the experimental verification of the effect of the multiple candidate waves on the particles' pitch-angle distributions has not been definitively established. This project brings together height-resolved measurements of ionization in the ionosphere, in situ measurements of pitch-angle scattering in the inner magnetosphere, and multidisciplinary expertise to achieve closure for all wave modes that may be involved in electron precipitation mechanisms. Instances of temporally coincident Van Allen Probes' measurements of particles and waves in the radiation belt (or ring current) and Poker Flat Incoherent Scatter Radar (PFISR) measurements of particles precipitating into the ionosphere near the foot-point of the Van Allen Probes' flux tubes will be identified. The loss-cone distribution functions created by candidate waves for pitch-angle scattering using the quasi-linear diffusion equations will be calculated. Changes in the phase-space distribution of electrons that are produced by the electric and magnetic wave fields in the frequency range from a few Hz to several kHz will be quantified by applying UCLAs Full Diffusion Code to Van Allen Probes' particle and field measurements. Finally, a comparison of the ionization profiles produced in the atmosphere by loss cone distributions calculated from Van Allen Probes' data with the ionization profiles directly measured with PFISR.