Dynamics of Atmospheres and Magneto-Fluids in our Solar-Planetary Environment

在过去十年中，在太阳和太阳系行星体的观测和测量方面有了巨大的发展，计划在不久的将来取得进一步的进展。这些进展中有很大一部分是通过天基仪器取得的，例如卡西尼、朱诺、日诺、SDO、IRIS和帕克太阳探测器上的仪器，但随着DKIST最近的第一次亮相，地面仪器在未来也将发挥重要作用。除了这些新的和未来的(如太阳轨道器、蜻蜓)飞行任务外，还有一些重要的数据仍在使用，例如威尔科克斯山太阳天文台正在获取的长期磁图数据。这些丰富的数据使太阳系研究成为理论家的梦想，可获得的高质量数据为任何正在开发的理论提供了重要的指导和约束。我们计划的重点是使用理论和数值研究来详细研究太阳系中发生的一系列重要的动力学过程。在行星物理领域，我们提出了三项研究，着眼于三个非常不同的行星天体的大气动力学：火星、木星和土卫六。埃克塞特在模拟地球大气层方面的专业知识，由于我们与附近气象局的密切联系而得到加强，将在我们调查这三个行星时得到进一步发展和扩展。我们将利用这一专业知识来研究火星极地涡旋在火星两极惊人的水冰和尘埃层形成中的作用。火星极地涡旋具有不同寻常的环状结构。朱诺号观测到的木星大气动力学，在木星两极发现了极涡晶体。将对这种涡旋结构的形成过程进行测试。土卫六是一个重要的行星体，因为它与地球相似，拥有厚厚的氮气大气和以甲烷为基础的水文循环。我们打算研究泰坦大气环流的驱动因素，以及它是如何与甲烷循环相互作用的。能量通过统称为太阳发电机的过程传递到太阳内部的磁场，是太阳活动背后的驱动因素。因此，了解太阳能发电机是了解空间气候和空间天气的关键一步，后者在英国的风险登记册上。我们将发展一种基于频率平均的新形式的平均场发电机理论，不同于使用空间或时间平均的经典理论。通过理论和观测研究计算光球边界的螺旋度通量，我们将获得一致和彻底的太阳螺旋度平衡的解释，为发电机过程提供约束。此外，最近发展的小波方法将被用于理解磁螺旋的局部化。日冕中的磁流体动力学湍流和进入太阳风的磁流体力学湍流在传输(质量和能量)和耗散方面都是一个非常重要的过程。在湍流的研究中，我们提出了两个重点研究湍流动力学的方案。第一个研究日冕(或针状物)和日冕交界处的湍流的作用，以了解湍流在系统热力学演化中的作用。我们还将通过研究电子MHD中的惠斯勒波相互作用来研究MHD尺度以外的湍流能量级联。最后，我们将通过公开讲座和工作坊向公众和学校传达我们的工作。

There has been tremendous development over the past decade, with further advances planned in the near future, in the observation and measurement of the Sun and the planetary bodies of the solar system. A huge amount of this progress has been made through space-based instruments, for example those on Cassini, Juno, Hinode, SDO, IRIS and Parker Solar Probe, but with the recent first light of DKIST ground-based instrumentation also has an important future role to play. As well as these new, and future (e.g. Solar Orbiter, Dragonfly) missions, the important data that is still being taken by older instruments, for example the long term magnetogram data that is being taken at Mount Wilcox Solar Observatory. This wealth of data makes study of the solar system a theorist's dream, where the high-quality data available provides important guidance and constraints on any theory being developed. Our proposed programme focuses on using theoretical and numerical studies to make detailed investigations of a huge range of important dynamical processes that occur across our solar system.In the area of Planetary physics we propose three studies looking at the atmospheric dynamics of three very different planetary bodies: Mars, Jupiter and Titan. The expertise in Exeter of modelling the Earth's atmosphere, strengthened by our close links with the nearby Met Office, will be further developed and extended as we investigate these three planetary bodies. We will use this expertise to investigate the role of Martian polar vortices, with their unusual 'annular' structure, in the formation of the striking water ice and dust layers at the poles of Mars. The atmospheric dynamics of Jupiter, as observed by Juno, discovered polar vortex crystals at the poles of Jupiter. The formation processes of this vortex structure will be tested. Titan, an important planetary body due to its similarity to Earth, has a thick nitrogen atmosphere and a hydrology cycle based on methane. We propose to investigate the drivers of Titan's general circulation and how it interacts with the methane cycle.The energy transferred to the magnetic field in the solar interior through the processes collectively known as the solar dynamo is the driver behind solar activity. Therefore, understanding the solar dynamo is a key step towards understanding both space climate and space weather, the latter of which is on the UK risk register. We will develop a new form of mean-field dynamo theory based on frequency averaging, unlike the classical theories that use averages in either space or time. By calculating the helicity flux at the photospheric boundary through theoretical and observational studies, we will obtain a consistent and thorough account of helicity balance in the Sun, providing constraints on the dynamo processes. Furthering this, new methods recently developed involving wavelets will be applied to understand the localisation of magnetic helicity.Magnetohydrodynamic turbulence in the solar corona and out into the solar wind is a hugely important process both in terms of transport (both of mass and energy) and in terms of dissipation. In the study of turbulence we propose two projects that focus on turbulent dynamics. The first studies the role of turbulence at the boundary between prominences (or spicules) and the solar corona, to understand the role of the turbulence in the thermodynamic evolution of the system. We will also investigate the turbulent energy cascade beyond the MHD scales through a study of Whistler wave interactions in Electron MHD.Finally, we shall communicate our work to the public and to schools, through the use of public lectures and workshops.