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Balancing the magnetosphere's magnetic flux budget

平衡磁层的磁通量预算

基本信息

批准号：
ST/K004298/2
负责人：
Robert Fear
金额：
$ 45.19万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FK004298%2F2
关键词：
Balancing magnetosphere magnetic flux budget

项目摘要

Many bodies in the universe have their own magnetic fields. The Sun's magnetic field extends out to the furthest reaches of the Solar System, and the magnetic field of a magnetised planet carves out a region of space called the planet's "magnetosphere". It is the interplay between the magnetic fields of the Sun and the Earth's magnetosphere that transfers huge amounts of energy and drives most of the activity within the magnetosphere. In this study, I will gain a more comprehensive understanding of the fundamental processes driving this response. However, a wider application of the science in this field is the ever-improving forecasts of space weather (the conditions in near-Earth space). This is of real importance in the modern age, with our reliance on satellites and other technologies that are sensitive to solar activity.We know broadly how the region of space near Earth responds to solar activity. The Sun continuously spews out a hot gas (a plasma) called the solar wind, which flows through the Solar System. As it does so, it carries the Sun's magnetic field with it. The Earth's magnetic field protects us from the solar wind by forming a cavity called the magnetosphere. As the solar wind buffets the magnetosphere, the Sun's and Earth's magnetic fields collide. Sometimes, the two magnetic fields interlock and become connected in a process called 'reconnection'. This transfers energy from the Sun to the magnetosphere. This energy drives a lot of dynamic processes in the magnetosphere, such as increases in the intensity of the Van Allen radiation belts and geomagnetic storms, which can damage satellites and infrastructure on the ground. When the energy is released energetic particles are deposited into the atmosphere. This gives off light in an oval-shaped band around the North Pole and another around the South Pole which is called the 'aurora' or the northern and southern lights. (In the north, the oval usually stretches through Scandinavia, Siberia, Alaska and Canada, which is why these are the best places to see the northern lights.)Many parts of this chain of events are poorly understood, and I will make advances in two key areas. Firstly, we do not understand exactly how the 'interlocking' process happens. We cannot even agree how much interlocking takes place; people have tried to measure this by using satellites and radars that see the effects in the ionosphere (a layer of the upper atmosphere), and get wildly different answers. By taking a new approach developed from some of my recent work, I will be able to measure this effect accurately; I am confident that my estimates from spacecraft and ionospheric measurements will agree.The second aspect I will study is how the magnetosphere behaves when the Earth's and Sun's magnetic fields do not interlock. We know that under these conditions auroras form in a different way - rather than just forming in an oval around the pole, they are also seen at higher latitudes. We do not fully comprehend how high latitude auroras are formed, or how the magnetosphere behaves under these conditions. By making measurements of both the aurora and the environment in the magnetosphere, I will be able to work this out.These two questions are different sides to the problem of understanding how our environment is driven by the solar wind. Gaining a thorough understanding of this is important for two reasons. First, space weather forecasting requires a detailed knowledge of how the magnetosphere works and how it responds to the solar wind. Second, the 'interlocking' process (reconnection) occurs throughout the universe, and so understanding it is vital if we are to comprehend the workings of a large number of astronomical objects. The quality and range of measurements that can be made in the magnetosphere make it the best place to observe and understand reconnection.

宇宙中的许多物体都有自己的磁场。太阳的磁场延伸到太阳系的最远处，而磁化行星的磁场在空间中划出一个区域，称为行星的“磁层”。太阳磁场和地球磁层之间的相互作用传递了大量的能量，并驱动了磁层内的大部分活动。在这项研究中，我将更全面地了解驱动这种反应的基本过程。然而，该科学在这一领域的更广泛应用是不断改进的空间天气（近地空间的条件）预报。这在现代具有真实的重要性，因为我们依赖卫星和其他对太阳活动敏感的技术，我们广泛了解近地空间区域如何对太阳活动作出反应。太阳不断地喷出一种叫做太阳风的热气体（等离子体），它流经太阳系。地球的磁场通过形成一个叫做磁层的空腔来保护我们不受太阳风的影响。当太阳风冲击磁层时，太阳和地球的磁场就会发生碰撞。有时候，两个磁场会在一个叫做“重连”的过程中互锁并连接起来。这将能量从太阳转移到磁层。这种能量驱动磁层中的许多动态过程，例如货车艾伦辐射带和地磁暴强度的增加，这可能会损坏卫星和地面基础设施。当能量被释放时，高能粒子被沉积到大气中。这发出的光在一个椭圆形带围绕北极和另一个围绕南极这就是所谓的“极光”或北方和南方的光。(In在北方，椭圆通常延伸到斯堪的纳维亚半岛、西伯利亚、阿拉斯加和加拿大，这就是为什么这些地方是观看北方极光的最佳地点。人们对这一系列事件的许多部分知之甚少，我将在两个关键领域取得进展。首先，我们并不完全理解“互锁”过程是如何发生的。我们甚至不能同意有多少联锁发生;人们试图通过使用卫星和雷达来测量这一点，这些卫星和雷达可以看到电离层（高层大气层）的影响，并得到截然不同的答案。通过采用一种从我最近的一些工作中发展出来的新方法，我将能够精确地测量这种效应;我相信我从航天器和电离层测量中得出的估计将是一致的。我将研究的第二个方面是当地球和太阳的磁场不互锁时，磁层的行为。我们知道，在这些条件下，极光以不同的方式形成-而不仅仅是在极地周围形成椭圆形，它们也可以在高纬度地区看到。我们并不完全了解高纬度极光是如何形成的，或者磁层在这些条件下是如何表现的。通过对极光和磁层环境的测量，我将能够解决这个问题。这两个问题是理解我们的环境如何被太阳风驱动的问题的不同方面。对这一点有一个透彻的理解是很重要的，原因有两个。首先，空间天气预报需要详细了解磁层如何运作以及它如何对太阳风作出反应。其次，“互锁”过程（重连）发生在整个宇宙中，因此如果我们要理解大量天体的运作，了解它是至关重要的。在磁层中可以进行的测量的质量和范围使其成为观察和理解重连的最佳场所。