The Effects of Coupled Wave Power and Plasma Properties on Radiation Belt Dynamics

地球的辐射带由高能带电粒子组成，它们像环形甜甜圈一样围绕着地球。它们是在60多年前太空时代开始时首次被发现的，但关于控制其行为的物理过程的相对重要性仍然存在许多问题。内辐射带通常位于磁赤道平面内600至6，000公里的高度，相对稳定，但外辐射带通常位于12，000至45，000公里的高度，具有高度动态性。在这里，相对论性电子的数量可以在从几分钟到几天的时间尺度上变化几个数量级。理解、建模并最终预测这些所谓的“杀手”电子的行为至关重要，因为这些粒子的增强通量可能会损坏卫星，并对太空中的人类构成风险。各种等离子体波与地球辐射带中的高能带电粒子共存。它们可以与相对论性电子强烈相互作用，并在带的动力学中发挥重要作用，尽管它们的确切作用尚未确定。两种非常重要的波模是哨声模合唱和等离子体层嘶嘶声。哨声模式合唱，所谓的，因为它经常类似于鸟在黎明合唱时转换成声音的鸣叫，起着双重作用，有助于加速和能量电子的损失。相比之下，等离子体层的嘶嘶声，如此命名是因为它在作为声音回放时类似于可听的嘶嘶声，主要是一种损失机制。我们提出的项目将评估两种波模式的作用，以了解基本的物理学和改进辐射带模型和预测。目前等离子体波与电子相互作用的模型使用基于空间位置和地磁活动的等离子体波模型。在每个位置的局部等离子体条件，这也是重要的辐射带的动力学建模，独立建模。然而，最近的研究表明，在辐射带建模中纳入对当地环境和波谱的同地测量十分重要。这些新的结果的任务，不仅由卫星定位和地磁活动，但也由当地环境的特点binned新的波模型的发展，合唱和plasmaspheric嘶嘶声使用这种新方法的作用，目前正在调查的辐射带的一个有限的区域的一部分，NERC资助的空间气象仪器测量建模和风险（SWIMMR）项目卫星风险。本研究主要限于28，000公里以内（磁赤道平面内）和绝对磁纬度小于21度的区域，不包括重要的地球静止轨道区域及更远的区域。在这个项目中，我们将使用来自另外四颗卫星的数据，THEMIS-A，-D，-E和Arase，以研究合唱和等离子体层嘶嘶声如何影响整个地球辐射带的高能电子的行为。这将增进我们对控制辐射带行为的过程的物理学的理解，对于空间天气的准确建模和预报至关重要。具体来说，我们将建立合唱团的重要性，在海拔超过28,000公里的加速和损失的高能电子在地球的外辐射带。我们还将建立中纬度（21 <|MLAT| < 42度）合唱和等离子体层嘶嘶声辐射带动力学。此外，我们将在最后一个封闭的漂移壳层的外部径向边界运行模拟，以研究径向扩散和合唱在整个外辐射带产生MeV电子的作用。研究结果还将用于改进我们的辐射带模型和预测，因此，对卫星工程师、运营商和保险公司将具有巨大价值。

The Earth's radiation belts consist of energetic charged particles which surround the Earth like a ring doughnut. They were first discovered over 60 years ago, at the beginning of the space age, but many questions remain regarding the relative importance of the physical processes controlling their behaviour. The inner radiation belt, which typically lies at altitudes between 600 and 6,000 km in the magnetic equatorial plane, is relatively stable, but the outer radiation belt, which typically lies at altitudes between 12,000 and 45,000 km, is highly dynamic. Here the number of relativistic electrons can vary by orders of magnitude on timescales ranging from minutes to days. Understanding, modelling and ultimately predicting the behaviour of these so called "killer" electrons is critical because enhanced fluxes of these particles can damage satellites and pose a risk to humans in space.A variety of plasma waves co-exist with the energetic charged particles in the Earth's radiation belts. They can interact strongly with the relativistic electrons and play a fundamental role in the dynamics of the belts, although their precise roles are yet to be determined. Two very important wave modes are whistler mode chorus and plasmaspheric hiss. Whistler mode chorus, so-called because it often resembles the twittering of birds in the dawn chorus when converted to sound, plays a dual role, contributing to both the acceleration and loss of energetic electrons. In contrast, plasmaspheric hiss, so-named because it resembles audible hiss when played back as sound, is primarily a loss mechanism. Our proposed project will assess the role of both wave modes to understand the basic physics and to improve radiation belt models and forecasts.Current models for the interaction of plasma waves with electrons use models of the plasma waves based on spatial location and geomagnetic activity. The local plasma conditions in each location, which are also important for modelling the dynamics of the radiation belts, are modelled independently. However, recent studies have shown that it is important to incorporate co-located measurements of the local environment and wave spectra in radiation belt modelling. These new results mandate the development of new wave models binned not only by satellite location and geomagnetic activity, but also by the characteristics of the local environment.The roles of chorus and plasmaspheric hiss using this new method are currently being investigated in a limited region of the radiation belts as part of the NERC-funded Space Weather Instrumentation Measurement Modelling and Risk (SWIMMR) project Sat-Risk. This study is mostly restricted to the region inside 28,000 km (in the magnetic equatorial plane) and absolute magnetic latitudes less than 21 degrees, excluding the important geostationary orbit region and beyond. In this project we will use data from four additional satellites, THEMIS-A, -D, -E and Arase, to study how chorus and plasmaspheric hiss influence the behaviour of energetic electrons throughout the Earth's radiation belts. This will improve our understanding of the physics of the processes governing the behaviour of the belts and is essential for the accurate modelling and forecasting of space weather. Specifically, we will establish the importance of chorus at altitudes greater than 28,000 km on the acceleration and loss of energetic electrons in the Earth's outer radiation belt. We will also establish the importance of mid-latitude (21 < |MLAT| < 42 degrees) chorus and plasmaspheric hiss on radiation belt dynamics. Furthermore, we will run simulations with the outer radial boundary at the last closed drift shell to examine the roles of radial diffusion and chorus in the generation of MeV electrons throughout the outer radiation belt. The results will also be used to improve our radiation belt models and forecasts and, as such, will be of great value to satellite engineers, operators and insurers.