Mercury's Nightside Magnetosphere Response to Southward IMF and ICMEs: MESSENGER Investigation and Comparisons With Earth’s Magnetosphere

太阳风和磁层之间的耦合导致强烈而独特的磁层和地磁活动，称为地球上的空间天气。水星的磁层结构与地球相似，但在几个重要方面有所不同。水星没有电离层，只有一个稀薄的外逸层，由于它靠近太阳，它的磁层面临着比地球更强的行星际磁场（IMF）和更低的Alfvénic马赫数。这些因素影响到太阳风和磁层之间的耦合以及低高度场向电流的闭合。然而，很少有研究探索水星耦合的性质。这一提议将对水星和地球的太阳风-磁层耦合进行全面比较。结果将是非常有影响力的，并广泛地有助于我们了解太阳风磁层耦合过程，特别是在这两个地球风格的磁层的磁层动力学和空间天气的IMF和场向电流闭合的作用。该项目将支持博士学位。该项目由一名学生、一名早期职业科学家、一名女科学家以及美国和英国之间的国际合作组成。拟议的项目旨在全面调查水星磁层的磁层模式，并将其与地球磁层中观察到的模式进行比较。磁层通量环流的响应模式，包括孤立亚暴、稳定磁层对流和磁层振荡，是太阳风-磁层耦合过程中的基本耦合模式和重要的空间天气现象。然而，缺乏对水星磁层中磁层模式的性质和驱动条件的全面调查，也缺乏对地球和水星磁层之间类似过程的性质和驱动因素的全面比较。我们将分析信使号的测量结果，并将其与地球磁层中类似过程的现有知识和模式进行比较。要解决的具体科学问题包括：一）调查水星磁层对向南行星际磁场和行星际日冕物质抛射的反应;二）将类似过程与地球磁层中的类似过程进行比较;以及iii）该奖项反映了NSF的法定使命，通过使用基金会的知识价值和更广泛的影响审查标准进行评估，认为值得支持。

The coupling between the solar wind and magnetosphere causes strong and distinct magnetospheric and geomagnetic activities, known as space weather on Earth. Mercury’s magnetosphere is structurally similar to Earth’s but differs in several important ways. Mercury does not have an ionosphere, but only a tenuous exosphere, and its magnetosphere faces stronger interplanetary magnetic fields (IMF) and lower Alfvénic Mach numbers than Earth due to its proximity to the Sun. These factors affect the coupling between the solar wind and the magnetosphere and the closure of field-aligned currents at low altitudes. However, few studies have explored the nature of the coupling at Mercury. This proposal will conduct a comprehensive comparison of the solar wind-magnetosphere coupling at Mercury and Earth. The results will be highly impactful and contribute broadly to our understanding of solar wind-magnetosphere coupling processes, especially the roles of the IMF and field-aligned current closure in magnetospheric dynamics and space weather at these two terrestrial-style magnetospheres. This project will support a Ph.D. student, an early career scientist, a female scientist, and international collaborations between the US and UK.The proposed project aims to comprehensively investigate the magnetospheric modes of Mercury’s magnetosphere and compare them with those observed in Earth’s magnetosphere. Magnetospheric response modes of flux circulations, including isolated substorms, steady magnetospheric convection, and sawtooth oscillations, are fundamental coupling modes and important space weather phenomena during solar wind-magnetosphere coupling. However, comprehensive investigations into the properties and driver conditions of magnetospheric modes in Mercury’s magnetosphere are lacking, as are comprehensive comparisons of the properties and drivers of similar processes between the magnetospheres of Earth and Mercury. We will analyze measurements from MESSENGER and compare them with the current knowledge and modes of similar processes in Earth’s magnetosphere. The specific science questions to be addressed include: i) investigating the response of Mercury’s magnetosphere to the southward interplanetary magnetic field (IMF) and interplanetary coronal mass ejections (ICMEs); ii) comparing similar processes to those in Earth’s magnetosphere; and iii) determining what can be learned from the comparison of similar processes between Earth and Mercury.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.