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

耦合波功率和等离子体特性对辐射带动力学的影响

• 批准号: NE/X000389/1
• 负责人: Nigel Meredith
• 金额: $ 103.41万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX000389%2F1
• 关键词: Effects; Coupled; Wave; Power; Plasma

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.

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多年前太空时代之初首次被发现的，但关于控制它们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600至6000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，是高度动态的。在这里，相对论电子的数量可以在从几分钟到几天的时间尺度上以数量级变化。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，因为这些粒子通量的增强会损坏卫星，并对太空中的人类构成威胁。在地球的辐射带中，各种等离子体波与高能带电粒子共存。它们可以与相对论性电子发生强烈的相互作用，并在辐射带的动力学中起着基本的作用，尽管它们的确切作用还有待确定。两种非常重要的波模式是哨声模式合唱和等离子体嘶嘶。惠斯勒模式合唱，之所以被称为“惠斯勒模式合唱”，是因为它在转换成声音时经常类似于黎明合唱中的鸟儿的啁啾，它起着双重作用，既有助于加速，也有助于高能电子的损失。相比之下，等离子体嘶嘶声主要是一种损失机制，之所以如此命名，是因为它在播放时类似于可听到的嘶嘶声。我们提出的项目将评估这两种波模式的作用，以了解基本物理和改进辐射带模型和预报。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。每个位置的局部等离子体条件对模拟辐射带的动力学也很重要，它们是独立建模的。然而，最近的研究表明，在辐射带模拟中结合局部环境和波谱的同地测量是很重要的。这些新结果要求开发新的波模型，不仅受卫星定位和地磁活动的影响，而且受当地环境特征的影响。作为nerc资助的空间气象仪器测量建模和风险（SWIMMR）项目卫星风险的一部分，使用这种新方法的合唱和等离子体嘶嘶声的作用目前正在辐射带的有限区域进行研究。本研究主要局限于28,000 km以内（磁赤道平面）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以外。在这个项目中，我们将使用另外四颗卫星THEMIS-A、-D、-E和Arase的数据来研究合唱和等离子体的嘶嘶声如何影响整个地球辐射带的高能电子的行为。这将提高我们对控制辐射带行为的物理过程的理解，对精确建模和预测空间天气至关重要。具体来说，我们将确定海拔超过28,000公里的合唱对地球外辐射带高能电子的加速和损失的重要性。我们还将建立中纬度（21 < |MLAT| < 42度）合唱和等离子体嘶嘶对辐射带动力学的重要性。此外，我们将在最后一个封闭漂移壳的外径向边界上进行模拟，以检验径向扩散和合唱在整个外辐射带产生MeV电子中的作用。研究结果还将用于改进我们的辐射带模型和预报，因此，对卫星工程师、运营商和保险公司将有很大的价值。

项目成果

New Chorus Diffusion Coefficients for Radiation Belt Modeling

用于辐射带建模的新合唱扩散系数

• DOI: 10.1029/2023ja031607
• 发表时间: 2023
• 期刊: Space Physics
• 作者: Wong J

Substorm Driven Chorus Waves: Decay Timescales and Implications for Pulsating Aurora

亚暴驱动的合唱波：衰变时间尺度和对脉动极光的影响

• DOI: 10.1029/2023ja031883
• 发表时间: 2024
• 期刊: Space Physics
• 作者: Troyer R

The challenge to understand the zoo of particle transport regimes during resonant wave-particle interactions for given survey-mode wave spectra

• DOI: 10.3389/fspas.2024.1332931
• 发表时间: 2024-03
• 期刊: Frontiers in Astronomy and Space Sciences
• 影响因子: 3
• 作者: Oliver Allanson;Donglai Ma;A. Osmane;Jay M. Albert;Jacob Bortnik;Clare E. J. Watt;Sandra C. Chapman;Joseph Spencer;Daniel J. Ratliff;Nigel P. Meredith;Thomas Elsden;Thomas Neukirch;David P. Hartley;Rachel Black;N. Watkins;S. Elvidge