Determining the geomagnetic and heliophysical parameters that control increases and decreases in Earth's outer radiation belt

地球的地球空间环境包含了一个动态的近相对论电子群体，这些电子被困在磁力线上，向外延伸到地球同步轨道，称为外辐射带(ORB)。这些电子可能会损坏航天器部件，甚至导致航天器终端故障，因此预测和现在预测地球上的条件对航天器的运行至关重要。球体中高能电子的数量是由加速和损耗过程共同决定的。电磁波可以使电子通过磁力线向内扩散，从而使电子获得能量。与此同时，其他电磁波群体可以将电子散射到大气损失锥中，导致粒子沉淀到高层大气中。目前基于物理学的辐射带模型需要电磁波的全球统计地图来驱动球体的动力学。然而，这些地图通常是由地磁指数来参数化的，地磁指数在地球内部的净电子损失或加速期间，例如分别在风暴的主要阶段和恢复阶段，可以采取相同的值。因此，这些模型可以使用相同的波群来尝试模拟ORB中的不同净变化。这就引出了两个基本问题：“在大气层中不同的净变化期间，电磁波的种群是什么？是什么决定了这些变化？”以及“波群或粒子群中的梯度是辐射带动力学的主导因素吗？”对美国宇航局范艾伦探测器任务辐射带中高能电子总数的观察表明，辐射带的变化可以分为快速损失、快速加速或稳定损失。使用现场和地面测量相结合的方法，我们将通过重新预测波和粒子的分布，根据球体是否正在经历快速损失、稳定损失或加速，并揭示它们之间的统计上的显著差异，来挑战波群的常见参数化。我们还将研究将波归类在同一波中是否可以改进辐射带的物理模型。

Earth's geospace environment incorporates a dynamic population of near-relativistic electrons trapped on magnetic field lines that extend out to geosynchronous orbit known as the Outer Radiation Belt (ORB). These electrons can damage spacecraft components and even cause terminal spacecraft failures thus forecasting and nowcasting the conditions in the ORB are critical to spacecraft operations. The number of energetic electrons in the ORB determined from a combination of acceleration and loss processes. Electromagnetic waves can cause electrons to diffuse inwards across magnetic field-lines, causing the electrons to gain energy. At the same time, other electromagnetic wave populations can scatter the electrons into the atmospheric loss cone, causing the particles to precipitate into the upper atmosphere. Current physics-based models of the radiation belts require global, statistical maps of electromagnetic waves to drive the dynamics of the ORB. However, these maps are commonly parameterised by geomagnetic indices which can take the same values during periods of net electron loss or acceleration within the ORB, such as during the main and recovery phases of storms respectively. As such, the models can be using the same wave populations to attempt to model different net changes in the ORB. This leads to two fundamental questions: "what are the electromagnetic wave populations during different net changes in the ORB and what dictates these changes?" and "are the wave populations or gradients in the particle populations the dominant factor in radiation belt dynamics?". Observations of the total number of energetic electrons in the radiation belt from the NASA Van Allen Probes mission hint that the changes in the radiation belt can be categorised as either rapid loss, rapid acceleration, or steady loss. Using a combination of in-situ and ground-based measurements, we will challenge the common parameterisation of the wave populations by re-casting the wave and particle distributions in terms of whether the ORB is undergoing rapid loss, steady loss or acceleration and revealing statistically significant differences between them. We will also examine whether categorising the waves in the same wave can improve physical models of the radiation belts.