The environment surrounding a planet dominated by its magnetic field (called the magnetosphere) shields the planet from the solar wind. The study of the dynamics of this region, in the terrestrial context, is now known as Space Weather and has its own American Geophysical Union Journal in recognition of its importance. Exactly how the magnetosphere responds to the solar wind and transports mass and energy is a fundamental problem. Understanding these processes on Earth permits a detailed examination through the use of in situ observations from international multi-spacecraft missions such as Cluster and THEMIS, which is also relevant to the magnetospheres of other planets and even neutron stars [1].
Understanding Space Weather has considerable urgency for our technology based society: The USA now funds a Space Weather Prediction Centre [2] (SWPC), and stresses the link between three regions which are traditionally studied independently: The Sun, interplanetary space (the solar wind) and the Earth’s environment (the magnetosphere and ionosphere). During intense Space Weather events power grids can fail causing blackouts, radio communications (including those via satellite) can become disrupted and GPS navigation can become inoperable. In 2014 the UK’s Met Office opened their Space Weather Operations Centre which, like SWPC and other forecast sites, offer predictions for the coming 24 and 48 hour periods.
Magnetospheres are energized by the solar wind, and this can take place through the Kelvin-Helmholtz instability at the magnetopause (observed both at Earth [3,4] and other planets such as Saturn [5]), or through buffeting by dynamic pressure perturbations in the solar wind [6]. Both these processes excite ’fast’ Magnetohydrodynamic (MHD) waves in the magnetosphere, which can propagate, disperse, and couple to other MHD modes. A detailed understanding of these processes can be used seismologically to understand properties and dynamics of the magnetosphere by comparison with observations. Indeed, recent observations from satellite mission such as Cluster [3] and THEMIS have provided the motivation for this proposal.
The PhD project will focus on theory and be complemented by simulations. It will suit someone with an Applied Maths/Physics background who enjoys analytical theory and computing.
The Earth’s magnetosphere is distorted by the solar wind and has a complex 3D structure. Recently it has become evident that earlier simplified models cannot capture the complexity of the MHD wave processes in 3D [7,8,9]. Thus there is the opportunity to investigate the fundamental physics of wave coupling processes which will have wide-ranging applications from planetary magnetospheres, to solar coronal magnetic fields, to pulsar magnetospheres.
The type of research undertaken will involve running simulations and analysing the results to identify the essential behaviour of the system. Given such insights from the simulations, we can then construct approximate analytical theory which can be benchmarked against simulations and provide results and concepts which can be exploited by the wider Space Weather community. Examples of the style of research can be found in [7,8,9].
Although the emphasis of the project is theoretical, we maintain strong links with observers of satellite data and groundbased measurements, and these guide our research and keep our results relevant to helping observers better understand their observations.
STFC funding is available for a PhD project on this subject to start immediately, subject to eligibility.
For more details about the group, please visit our website:
http://www-solar.mcs.st-and.ac.uk/.
For information about the School and the application procedure in general, please see:
https://www.st-andrews.ac.uk/maths/prospective/pg/phdprogrammes/.
[1] Rezania, V., and J. C. Samson, 2005,
https://doi.org/10.1051/0004-6361:20041796 [2]
http://www.swpc.noaa.gov/ [3] Foullon, C., et al., 2008,
https://doi.org/10.1029/2008JA013175 [4] Guo, X. C., C. Wang, and Y. Q. Hu, 2010,
https://doi.org/10.1029/2009JA015193 [5] Masters, A., J. Geophys. Res., 2011,
https://doi.org/10.1029/2010JA016421 [6] Takahashi, K. and A. Y. Ukhorskiy, 2008,
https://doi.org/10.1029/2008JA013327 [7] Wright, A. N., and T. Elsden, 2016,
http://dx.doi.org/10.3847/1538-4357/833/2/230 [8] Elsden, T., and A. N. Wright, 2017,
https://doi.org/10.1002/2016JA023811 [9] Elsden, T., and A. N. Wright, 2019,
https://doi.org/10.1009/2018JA026222
