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

在过去十年中，在观测和测量太阳和太阳系行星体方面取得了巨大的发展，并计划在不久的将来取得进一步的进展。这一进展中有很大一部分是通过天基仪器取得的，例如卡西尼号、朱诺号、日出号、SDO、IRIS和帕克太阳探测器上的仪器，但随着DKIST最近首次亮相，地基仪器也将在未来发挥重要作用。除了这些新的和未来的任务（如太阳轨道器，蜻蜓），重要的数据仍然是由旧的仪器，例如长期磁图数据，正在采取的威尔科克斯山太阳天文台。这些丰富的数据使研究太阳系成为理论家的梦想，高质量的数据为任何正在发展的理论提供了重要的指导和约束。我们提出的方案侧重于利用理论和数值研究，详细调查整个太阳系发生的大量重要动力学过程，在行星物理学领域，我们提出三项研究，研究三个非常不同的行星体：火星、木星和土卫六的大气动力学。在埃克塞特的专业知识模拟地球的大气层，加强了我们与附近的气象局的密切联系，将进一步发展和扩大，因为我们调查这三个行星机构。我们将利用这些专业知识来研究火星极地涡旋的作用，它们具有不寻常的“环形”结构，在火星极地形成引人注目的水冰和尘埃层。朱诺号观测到的木星大气动力学在木星的两极发现了极涡晶体。对这种涡旋结构的形成过程进行了实验研究。泰坦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层和基于甲烷的水文循环。我们建议调查泰坦大气环流的驱动因素以及它如何与甲烷循环相互作用。通过统称为太阳发电机的过程转移到太阳内部磁场的能量是太阳活动背后的驱动因素。因此，了解太阳发电机是了解空间气候和空间天气的关键一步，后者已列入联合王国风险登记册。我们将开发一种基于频率平均的新形式的平均场发电机理论，这与使用空间或时间平均值的经典理论不同。通过理论和观测研究计算在光球边界的螺旋度通量，我们将获得一个一致的和彻底的帐户在太阳的螺旋度平衡，提供发电机过程的约束。此外，最近开发的新方法，涉及小波将被应用于了解磁螺旋度的本地化。磁流体动力学湍流在太阳日冕和太阳风是一个非常重要的过程，无论是在运输（质量和能量）和耗散方面。在湍流的研究中，我们提出了两个项目，专注于湍流动力学。第一部分研究了湍流在日冕（或针状体）和日冕边界处的作用，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磁流体力学中的哨声波相互作用来研究磁流体力学尺度之外的湍流能量级联。最后，我们将通过公开讲座和研讨会向公众和学校宣传我们的工作。

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.