The transfer of solar wind energy into the upper atmosphere through magnetospheric waves

太阳和地球等离子体环境之间的相互作用是非常动态的，具有重要的社会和商业意义。这个太瓦系统的很大一部分能量通过磁流体动力学（MHD）波从外层磁层向内转移，这些波在磁层等离子体中沿着磁场线传播到上层大气（电离层）。在那里，能量通过摩擦（焦耳）加热和高能粒子沉淀（EPP）消散。图1给出了感兴趣的系统的概述。通过这项研究，学生将能够测量地磁活动对近地空间环境的影响。由于众所周知地磁暴会影响人类在地面和空间的活动，“空间天气”危害现已成为政府国家风险登记册的一部分。莱斯特大学的无线电和空间等离子体物理（RSPP）小组拥有独特的英国访问许多重要数据集的机会，包括来自卫星（例如范艾伦探测器，VAPs和最近发射的日本Arase任务），电离层雷达（包括SuperDARN和EISCAT）和地面磁力计（通过SuperMag）的数据集。MHD波可以大致归类为由外部（太阳风）驱动或激发，通过地球磁场和范艾伦带中漂移的等离子体之间的波粒相互作用。NASA的VAPs任务将观测磁层中的波，JAXA的Arase任务可以确定进入高层大气的EPP通量，而NASA的Wind航天器则监测太阳风驱动程序的背景。收集到的数据将为最新的MHD波浪产生和太阳对大气的强迫模式提供输入。与MHD波相关的电场驱动电离层运动，这可以通过使用莱斯特大学首创的技术的EISCAT和SuperDARN等雷达直接测量。同时，外部激发波（大尺度）也很容易被地面磁强计（SuperMag）探测到，而粒子驱动波（较小尺度）更容易在电离层和磁层内观测到。最初，将对上游太阳风（风）数据进行检查，以确定磁层驱动因素，并将这些数据与磁层内的测量（VAP和Arase）相结合，以提供一种确定MHD波是如何产生的方法，并估计传递到上层大气的能量和EPP通量。将得到一个事件及其特征的数据库。这些模型将与现有的MHD波模型进行比较。这些观测结果将与EISCAT和SuperDARN雷达（包括2021年在芬兰部署的新型数字雷达）的同期测量结果相结合，以提供在确定事件期间发生的电离层电导率、电动力学和EPP的详细图像。此外，学生将利用一种新开发的分析方法（基于Lomb-Scargle周期图）来检查SuperDARN测量结果和SuperMag提供的地磁强计数据中的MHD波特征。最终，学生将确定从太阳风到电离层的能量路径，并提供通过这些路径转移的总能量的准确估计。该项目将建立在无线电和空间等离子体物理（RSPP）小组在开发和分析地球物理数据以及结合地面和空间观测空间天气现象方面40多年的经验基础上。将提供有关等离子体和大气物理及雷达技术方面的培训，以及计算机编程、模型模拟和所需数据分析方面的培训。学生将在研究方法、数据管理、分析思维和计算机编程方面获得大量专业知识。

The interaction between the Sun's and the Earth's plasma environments is very dynamic and one of societal and commercial importance. A large proportion of the energy from this terawatt system is transferred from the outer magnetosphere inwards by magnetohydrodynamic (MHD) waves, which propagate in the magnetospheric plasma along magnetic field lines into the upper atmosphere (ionosphere). There, the energy is dissipated through frictional (Joule) heating and energetic particle precipitation (EPP). Fig. 1 presents an overview of the system of interest. By undertaking this study, the student will be able to gauge the impact of geomagnetic activity on the near-Earth space environment. "Space Weather" hazards are now part of the Government's National Risk Register since geomagnetic storms are known to affect human activities on the ground and in space. The Radio and Space Plasma Physics (RSPP) group at the University of Leicester has unique UK access to a number of important data sets including those from satellites (e.g. the Van Allen Probes, VAPs and the recently launched Japanese Arase mission), ionospheric radars (including SuperDARN and EISCAT) and ground magnetometers (through SuperMag). MHD waves can be broadly categorised as being externally (solar wind) driven or excited through wave -particle interactions between the Earth's magnetic field and drifting plasma in the van Allen belts. The NASA VAPs mission will observe waves in the magnetosphere and the JAXA Arase mission can determine the flux of EPP entering the upper atmosphere, whilst the NASA Wind spacecraft monitors the solar wind driver for context. The data collected will provide input to up-to-date models of MHD wave generation and solar forcing of the atmosphere. The electric fields associated with MHD waves drive the ionosphere into motion, which is directly measurable by radars such as EISCAT and SuperDARN using techniques pioneered at Leicester. Simultaneously, externally-excited waves (with large scale sizes) are also readily detected by ground magnetometers (SuperMag) whereas particle-driven (smaller scale) waves are more easily observed within the ionosphere and magnetosphere. Initially, an examination of upstream solar wind (Wind) data will be undertaken to determine magnetospheric drivers and these will be combined with measurements within the magnetosphere (VAP and Arase) to provide a way of determining how the MHD waves are generated and estimates of energy and EPP fluxes which are delivered to the upper atmosphere. A database of events and their characteristics will be derived. These will be compared with existing models of MHD waves. The observations will be exploited in conjunction with contemporaneous measurements from the EISCAT and SuperDARN radars (including a new digital radar being deployed in Finland in 2021) to provide a detailed picture of the ionospheric conductivity, electrodynamics and EPP occurring during events identified. In addition, the student will utilise a newly developed analysis method (based on the Lomb-Scargle periodogram) to examine the MHD wave signatures in both the SuperDARN measurements and in ground magnetometer data provided by SuperMag. Ultimately, the student will determine the energy pathways from the solar wind into the ionosphere and provide accurate estimates of the total energy transferred through these routes.The project will build upon over 40 years of experience within the Radio and Space Plasma Physics (RSPP) group in the exploitation and analysis of geophysical data and combining ground- and space-based observations of Space Weather phenomena. Training in relevant plasma and atmospheric physics and radar techniques will be provided as well as training in computer programming, model simulations and the data analysis required. The student will gain a great deal of expertise in research methods, data management, analytical thinking and computer programming.