Magnetism and Fluid Flows in our Solar-Planetary Environment

Over the past few years, a suite of space missions has been launched to provide incredibly high-precision measurements and observations of the Sun, the solar wind and Jupiter (for example Juno, Hinode, Cluster, SDO and IRIS). When put together with the large coverage by ground based observations and future instruments like DKIST and Solar Orbiter, the increase in computational power over recent years and great theoretical advances, this is an amazing time to be studying our solar system. Combining observations with theoretical and numerical work will allow us to probe the fundamental physics behind magnetic field generation in astrophysical systems, the important plasma processes like turbulence and shocks, and work towards a comprehensive understanding of space weather, which is on the UK risk register. Within this proposal we aim to study a huge range of important dynamical processes that occur across our solar system.

Our work on Planetary physics involves two complementary studies of the structure of Jupiter. The NASA Juno spacecraft entered into orbit around Jupiter in July 2016, and will be surveying the planet until February 2018. It will observe atmospheric dynamics as well as provide insights into interior dynamics. In particular, measurements of the gravitational potential will allow detailed information on the mass distribution within the planet, while also providing crucial observations of the weather layer. Theoretical modelling of the fluid dynamics in the interior and its link to the weather layer is thus very timely, and these projects will establish Exeter and the U.K. as leaders in interpreting Jovian fluid dynamics. We will examine the interaction between atmospheric and interior fluid flows -- for example, are atmospheric jets manifestations of the interior and do they connect to the deep jets? We will conduct intensive numerical modelling of the planet's interior in order to directly interpret the gravitational data from Juno.

The solar dynamo is the root of magnetic field in the solar atmosphere and the field carried throughout the heliosphere by the solar wind. The tachocline, which is the focus of a number of our projects, is believed to be of huge importance for the storing and enhancing of magnetic field during the dynamo process. We will investigate fundamental magnetohydrodynamic processes in rotating fluids and stratified fluids as relevant to understanding the tachocline and the solar convection zone. We will look at magnetic fields in thin fluid layers with important applications to zonal jet formation, and we will look at the structures that form as a result of stably stratified MHD turbulence in the tachocline. We will also 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.

We will use numerical modelling, observations and in-situ measurements to investigate the dynamics of the solar atmosphere and how this relates to eruptions. MHD shocks are known to be key for many dynamic processes in the chromosphere, including heating. Being partially ionised, this can greatly influence the structure of an MHD shock. We will investigate the role of partial ionization in the heating and dynamics of the chromosphere. By calculating the helicity flux at the photospheric boundary and in the solar wind through theoretical and observational studies, we will obtain a consistent and thorough account of helicity balance in the Sun and heliosphere. We will also look at the dynamics of solar eruptions, including those of the Kelvin-Helmholtz. These will be used to determine the observational signatures that can be used to predict the structure of ejecta observed at 1 A.U. Obviously, the space weather forecasting implications of this study are huge.

Finally, we shall communicate our work to the public and to schools, through the use of public lectures and workshops.

The potential impacts of this proposal can be divided into two sections: Societal and Economic. In all cases relevant projects are listed in brackets.

On the societal side, we propose an extensive public engagement programme that takes in aspects from our research and our proposed research programmes. The University of Exeter supports these activities in a number of ways, including providing monitoring and evaluation forms to assess the impact of subject-based workshops and a team who analyse evaluation forms and provide impact summaries.

Our program includes a range of lectures to the general public. Those we plan based on our research projects include:
weather on other planets, with Jupiter as the key example (1.1); highlighting the results from Juno and showing how they can be used to understand the internal structure of Jupiter (1.2); and highlighting the risks of space weather and how to predict it (2.1 & 2.6). These activities are very important to relay the key results of our work to the public, helping them to understand the role our research plays in their lives.

In conjunction with our public lecture programme we will also offer a range of workshops and mathematics classes for school students aimed at stimulating children's interest in mathematics though vibrant applications to solar and planetary physics. While these activities tend to be mathematical in nature, we are always careful to emphasises the applications to our research. Our group has particularly strong links with Exeter Mathematics School, a University-supported sixth form free school for talented mathematicians in the southwest, but we are also involved in RI Mathematics Masterclasses and other school outreach programs. Those lessons we plan based on our research programme include: studying the mathematics of space weather (2.1, 2.6) and heating the solar atmosphere (2.5); and examining the fundamental properties of fluid flow and magnetic field generation in the solar interior (2.2, 2.3, 2.4). These activities introduce young students to new mathematical techniques through the wonder of studying planetary and solar physics. Outreach activities of this kind are also impactful as they can discuss the range of skills and job-types that go into doing research, including programming, fluid-dynamics and engineering, and they give students a view of our place in the Universe.

The economic impacts to industry of space weather should not be underestimated, especially considering that it is included on the UK risk register. Our unique position, due to our group's long-standing connections to the Met Office, mean that we are well placed to collaborate with the Met Office as they develop their space-weather forecasting capabilities. Given the growing importance of Space Weather for the UK and the region around Exeter, we aim to develop image and in-situ data processing algorithms with applications for real-time monitoring and space weather forecasting (UoE/MO, 2.1, 2.6).