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

该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传播的机制。确定这些机制对于了解近地环境的不同层次是如何耦合的很重要。了解中性和带电大气层对于了解空间气象事件发生的背景越来越感兴趣。将结合航天器数据分析来自美国国家科学基金会支持的设施的数据，如高级模块化非相干散射雷达(阿米西里雷达)。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，由于与地磁赤道或附近的波相互作用，磁层中的高能粒子经过俯仰角散射进入损失锥后，沉淀到大气中。然而，多个候选波对颗粒俯仰角分布影响的实验验证还没有得到明确的证实。该项目汇集了对电离层电离的高分辨率测量、对内磁层俯仰角散射的现场测量以及多学科的专门知识，以实现关闭可能涉及电子沉淀机制的所有波模。将识别在时间上一致的Van Allen探测器对辐射带(或环电流)中的粒子和波的测量以及对Van Allen探测器通量管脚点附近进入电离层的粒子的扑克平坦非相干散射雷达(PFISR)测量的实例。利用拟线性扩散方程，计算俯仰角散射的候选波产生的损失锥分布函数。在几赫兹到几千赫兹的频率范围内，电波场和磁波场产生的电子的相空间分布的变化将通过将UCLAS全扩散代码应用于Van Allen探测器的粒子和场测量来量化。最后，比较了由Van Allen探测器数据计算的损耗锥分布在大气中产生的电离分布与用PFISR直接测量的电离分布。

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.