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

确定控制地球外辐射带增减的地磁和太阳物理参数

• 批准号: 2903408
• 金额: --
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2903408
• 关键词: Determining; geomagnetic; heliophysical; parameters; control

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.

地球的地球空间环境包含了被捕获在磁场线上的动态近相对论电子群，这些电子延伸到称为外辐射带（ORB）的地球同步轨道。这些电子会损坏航天器部件，甚至导致航天器末期故障，因此预测和临近预报 ORB 中的状况对于航天器运行至关重要。 ORB 中高能电子的数量由加速和损失过程的组合决定。电磁波可以导致电子穿过磁场线向内扩散，从而使电子获得能量。与此同时，其他电磁波群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。当前基于物理的辐射带模型需要电磁波的全局统计图来驱动 ORB 的动力学。然而，这些地图通常由地磁指数参数化，地磁指数在 ORB 内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）可以取相同的值。因此，模型可以使用相同的波群来尝试模拟 ORB 中不同的净变化。这就引出了两个基本问题：“ORB 中不同净变化期间的电磁波群是什么，以及什么决定了这些变化？”和“波群或粒子群中的梯度是辐射带动力学的主导因素吗？”。美国宇航局范艾伦探测器任务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。通过结合现场和地面测量，我们将根据 ORB 是否正在经历快速损失、稳定损失或加速来重新构建波和粒子分布，并通过统计数据揭示波群的常见参数化它们之间存在显着差异。我们还将研究将波分类在同一波中是否可以改进辐射带的物理模型。