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性电子群，这些电子被困在磁场线上，这些磁场线延伸到被称为外辐射带（ORB）的地球同步轨道。这些电子会损坏航天器部件，甚至导致航天器终端故障，因此预测和临近预报ORB中的条件对航天器操作至关重要。ORB中高能电子的数量由加速和损失过程的组合确定。电磁波可以使电子穿过磁力线向内扩散，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全球的电磁波统计图来驱动ORB的动力学。然而，这些地图通常由地磁指数参数化，这些指数在ORB内的净电子损失或加速期间可以取相同的值，例如分别在风暴的主要和恢复阶段。因此，模型可以使用相同的波群来尝试对ORB中的不同净变化进行建模。这就引出了两个基本问题：“在ORB的不同净变化期间，电磁波的数量是多少？是什么决定了这些变化？”“和“波群或粒子群梯度是辐射带动力学的主导因素吗？".美国宇航局货车艾伦探测器使命对辐射带中高能电子总数的观测表明，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，我们将挑战波群的常见参数化，通过重新铸造波和粒子分布方面的ORB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显着差异。我们还将研究是否将波分类在同一波中可以改善辐射带的物理模型。

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.