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穿过大气层的机制。确定这些机制对于了解近地环境各层之间的耦合关系非常重要。了解中性和带电大气层对于了解空间天气事件的背景越来越有意义。来自美国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）的数据将结合航天器数据进行分析。目前的粒子沉淀理论假设，磁层中的高能粒子在与地磁赤道或附近的波相互作用后，经过俯仰角散射进入损失锥，然后沉淀到大气中。然而，多个候选波对粒子的俯仰角分布的影响的实验验证尚未明确建立。该项目汇集了电离层电离的高度分辨测量、内磁层俯仰角散射的现场测量以及多学科专门知识，以封闭可能参与电子沉淀机制的所有波模式。将确定货车艾伦探测器对辐射带（或环电流）中粒子和波的时间同步测量结果和扑克牌平板非相干散射雷达对货车艾伦探测器通量管脚点附近沉淀到电离层中的粒子的测量结果。将使用准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。通过将UCLA全扩散代码应用于货车艾伦探针的粒子和场测量，将在几Hz到几kHz的频率范围内由电场和磁场产生的电子的相空间分布的变化量化。最后，将由货车艾伦探测器的数据计算的损失锥分布在大气中产生的电离剖面与用PFISR直接测量的电离剖面进行了比较。

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.