Balancing the magnetosphere's magnetic flux budget

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端，而被磁化的行星的磁场划出了一个空间区域，称为行星的“磁层”。正是太阳和地球磁层的磁场之间的相互作用，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，我将更全面地了解推动这一反应的基本过程。然而，科学在这一领域的更广泛应用是对空间天气(近地空间的条件)的不断改进的预报。这在现代是非常重要的，因为我们依赖于对太阳活动敏感的卫星和其他技术。我们大致知道地球附近的空间区域对太阳活动的反应。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。当它这样做的时候，它携带着太阳的磁场。地球磁场通过形成一个叫做磁层的空腔来保护我们免受太阳风的侵袭。当太阳风冲击磁层时，太阳和地球的磁场会发生碰撞。有时，这两个磁场相互交错并在一种称为“重新连接”的过程中连接在一起。这将能量从太阳转移到磁层。这种能量驱动了磁层中的许多动态过程，例如范艾伦辐射带强度的增加和地球磁暴，这可能会破坏卫星和地面基础设施。当能量释放时，高能粒子被沉积到大气中。它在北极周围发出椭圆形的光带，在南极周围发出另一束光，这被称为“极光”或北极光和南极光。(在北部，椭圆形通常横跨斯堪的纳维亚、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，我们并不确切地了解“联锁”过程是如何发生的。我们甚至无法就有多少连锁发生达成一致；人们试图通过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(高层大气层的一层)的影响，并得到了截然不同的答案。通过采用一种从我最近的一些工作中发展出来的新方法，我将能够准确地测量这种影响；我相信我从航天器和电离层测量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相互作用时，磁层的行为如何。我们知道，在这种情况下，极光以一种不同的方式形成--而不仅仅是在极点周围的椭圆形中形成，它们也可以在更高的纬度看到。我们还没有完全理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行为的。通过测量极光和磁层中的环境，我将能够解决这个问题。这两个问题是理解我们的环境是如何受到太阳风驱动的问题的不同方面。彻底了解这一点很重要，原因有两个。首先，空间天气预报需要详细了解磁层如何工作，以及它如何对太阳风作出反应。其次，整个宇宙中都存在着“互锁”过程(重新连接)，因此，如果我们要理解大量天文天体的工作原理，理解这个过程是至关重要的。磁层测量的质量和范围使其成为观察和了解重联的最佳场所。

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.