Imaging the Earth's magnetosphere response to solar wind variability

成像地球磁层对太阳风变化的响应

• 批准号: 2728040
• 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: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2728040
• 关键词: Imaging; Earth; magnetosphere; response; solar

It is known that soft X-rays are produced in the Earth's magnetosheath and cusps by the process of charge exchange between solar wind ions and neutrals in the Earth's exosphere. The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE - https://mssl.ucl.ac.uk/SMILE/) is a joint mission of the European Space Agency and the Chinese Academy of Sciences that will study the interaction of the solar wind with the Earth's magnetosphere. At the end of 2024 the mission will take into space four instruments, two of them being imagers, the Soft X-ray Imager (SXI) and the UV Imager (UVI). SXI will take X-ray images of the dayside magnetosphere with the purpose of studying its response to solar wind variations in a totally new way.In order to understand the data SMILE will return, we are simulating the X-rays emitted by the cusp and magnetosheath and the output of SXI.The motivation behind this PhD project is that of studying large-scale magnetic reconnection at the dayside magnetopause and transitions between different magnetospheric modes. Dayside reconnection is induced by an increase in the solar wind dynamic pressure and/or a southward interplanetary magnetic field (IMF) turning. So far, many modelling and observational studies have been devoted to the magnetospheric response to solar wind pressure jumps (e.g. interplanetary shocks) and to solar wind tangential/rotational discontinuities. These phenomena are part of what we call 'space weather', representing the impact of solar wind variability on environmental conditions in near Earth space, which can have severe disrupting consequences on our technological infrastructure, in space and on the ground. A particularly interesting issue is the magnetospheric response to southward IMF turnings. This is important in magnetospheric physics because the IMF component orthogonal to the equatorial plane is thought to be one of the most important driving parameters for the solar wind - magnetosphere interaction. And it is a topic that has great potential for investigations applying SMILE imaging.Questions that the project will try to find an answer to are like: Which types of solar wind structures are related to southward IMF turnings? Are they the sort of conditions that lead to geomagnetic storms and substorms? In addition, there are many other unresolved issues that a PhD project in this area can address. For example, we know that the magnetopause shape and position are different for northward and southward IMF but the empirical and MHD models we have do not describe them accurately. MHD model runs, combined with observations from spacecraft, could better constrain the mathematical form of the magnetopause shape.

众所周知，软X射线是通过太阳风离子与地球外逸层中中性粒子之间的电荷交换过程在地球磁鞘和尖点产生的。太阳风磁层电离层链接探测器（SMILE - https://mssl.ucl.ac.uk/SMILE/）是欧洲航天局和中国科学院的联合任务，将研究太阳风与地球磁层的相互作用。到 2024 年底，该任务将把四台仪器送入太空，其中两台是成像仪，即软 X 射线成像仪 (SXI) 和紫外线成像仪 (UVI)。 SXI 将拍摄阳侧磁层的 X 射线图像，目的是以全新的方式研究其对太阳风变化的响应。为了了解 SMILE 将返回的数据，我们正在模拟尖点和磁鞘发射的 X 射线以及 SXI 的输出。这个博士项目背后的动机是研究阳侧磁层顶的大规模磁重联以及不同磁层之间的转变 模式。日侧重联是由太阳风动态压力的增加和/或向南的行星际磁场（IMF）转向引起的。到目前为止，许多建模和观测研究都致力于磁层对太阳风压力跳跃（例如行星际激波）和太阳风切向/旋转不连续性的响应。这些现象是我们所说的“太空天气”的一部分，代表太阳风变化对近地空间环境条件的影响，这可能对我们太空和地面的技术基础设施产生严重的破坏性后果。一个特别有趣的问题是磁层对国际货币基金组织南转的响应。这在磁层物理学中很重要，因为正交于赤道面的 IMF 分量被认为是太阳风 - 磁层相互作用最重要的驱动参数之一。这是一个在应用 SMILE 成像进行研究方面具有巨大潜力的主题。该项目将试图找到答案的问题包括：哪些类型的太阳风结构与南向 IMF 转向有关？它们是导致地磁风暴和亚暴的条件吗？此外，该领域的博士项目还可以解决许多其他未解决的问题。例如，我们知道北向和南向 IMF 的磁层顶形状和位置是不同的，但我们的经验模型和 MHD 模型并没有准确地描述它们。 MHD 模型的运行与航天器的观测相结合，可以更好地约束磁层顶形状的数学形式。