Global simulations of planetary magnetospheres

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

Large-scale global simulations are a powerful tool for studying the physics of how planetary magnetospheres form and evolve. Whilst much effort has been directed at modelling and understanding the Earth's magnetosphere, computer simulations have also been used to model all the magnetized planets - Mercury, Jupiter, Saturn, Uranus and Neptune. A key question pertaining to the solar wind - magnetosphere interaction is the role of magnetic reconnection in enabling plasma to circulate throughout the magnetosphere. At Earth, it is commonly understood that reconnection is of primary importance, but asymmetric boundary conditions, flow shear, magnetic field orientations, and the 3d geometry all control its occurrence, location, and efficiency. Therefore the role of magnetic reconnection in magnetospheric dynamics in general is still not completely understood. The goal of this PhD project is to use Imperial College's High Performance Computing (HPC) system and computer codes developed in the Imperial College plasma physics group to perform simulations of the global solar wind-magnetosphere interaction, to better understand when and where magnetic reconnection may occur on the boundaries of planetary magnetospheres, firstly at Earth, but with applications to other planets in the solar system and also exoplanet magnetospheres.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/R504816/1 30/09/2017 29/09/2021
1962712 Studentship ST/R504816/1 30/09/2017 29/04/2021 Joseph EGGINGTON
 
Description The work achieved through this studentship involved direct contribution to the development of the Gorgon MHD code for simulating planetary magnetospheres. In particular, a model ionosphere was integrated into the code and tested, capturing magnetosphere-ionosphere coupling which is a crucial component in accurately modelling geospace. Various post-processing software tools were developed for visualisation and analysis of the simulation outputs, such as for studying phenomena like magnetic reconnection and ionospheric convection. This greatly improved the capability of the Gorgon code as a research tool in magnetospheric physics.

The studies performed during this studentship explored the nature of solar wind-magnetosphere-ionosphere coupling, its drivers, and the timescales over which it occurs. Through the use of global simulations it was shown that the tilt angle of the Earth's magnetic field, which varies daily and seasonally, closely modulates the interaction between the solar wind and magnetosphere, and results in interhemispheric asymmetries in the system that manifest in the ionosphere. For extreme tilt angles which can occur over geological timescales, these currents may become increasingly localised and asymmetric depending on the time of day or year. Simulations of synthetic extreme space weather events were also performed which revealed how strong compression of the magnetosphere by an interplanetary shock results in much more intense magnetic reconnection during the compression, and with a strong time-dependence that may not be captured by empirical models. The code was then extended to simulate a real space weather event, exploring the timescales over which changes in the configuration of the magnetosphere are communicated from the solar wind and ultimately into the ionosphere during a geomagnetic storm. It was found that this occurs over timescales of hours, dependent on the balance between magnetic reconnection at the dayside and nightside magnetosphere. As well as forming the body of work in my PhD thesis, these results were published in a peer-reviewed journal article, and contributed to two further articles, one of which is currently under peer-review and the other in preparation for submission to peer-review. In addition to these, the work contributed to two co-authored peer-reviewed journal articles.

Finally, the further development of the Gorgon model during this studentship has provided a significant step towards using the code for space weather forecasting. As well as allowing for fundamental studies into space weather, this also provides the foundations for modelling a real event using measured solar wind input data and generating real-time predictions of conditions in the magnetosphere and ionosphere. One example is the ability to use the simulation outputs to predict magnetic field perturbations on the ground, which affect infrastructure such as power grids. The work from this studentship will therefore not only benefit future Gorgon research into magnetospheric physics in general, but also other projects which utilise Gorgon as a space weather modelling tool.
Exploitation Route Much of the work from this studentship has provided an important basis for subsequent work in the NERC-funded SWIGS and SWIMMR/SAGE projects, in which Gorgon in being developed to better our understanding of the ground effects of space weather, and modified for operational forecasting purposes for predicting geomagnetic perturbations at UK latitudes. This will also greatly facilitate future collaborations with other UK and international space physics researchers. As part of the latter project, Gorgon may also be used in the future to provide forecasts to non-academic users (e.g. in the energy industry) as part of a Met Office suite of models.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Energy,Environment,Transport

 
Description Conference Funding
Amount £300 (GBP)
Organisation Imperial College London 
Department Imperial College Trust
Sector Charity/Non Profit
Country United Kingdom
Start 08/2018 
End 09/2018
 
Description Conference/Meeting Travel Subsistence
Amount £920 (GBP)
Organisation Royal Astronomical Society 
Sector Academic/University
Country United Kingdom
Start 12/2019 
End 12/2019
 
Title SWIGS: Gorgon Magnetohydrodyamic Code Simulation Data: Magnetospheric and Ionospheric Conditions under Southward IMF for 0-90 degree Dipole Tilts 
Description This dataset contains data outputs generated using the Gorgon Magnetohydrodynamic (MHD) code, for simulations of the steady-state magnetosphere-ionosphere system during southward interplanetary magnetic field (IMF) with dipole tilt angles from 0-90 degrees. This data were collected as part of the NERC project Space Weather Impacts on Ground-based Systems (SWIGS). The access rules are as follows: "Access to these data is available to any registered CEDA user. Please Login or Register for an account to gain access. Use of these data is covered by the following licence: http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record." 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact This database will be used to accompany a publication (currently under peer-review) in AGU's 'Journal of Geophysical Research: Space Physics', in accordance with the Enabling FAIR Data project policy. 
URL https://catalogue.ceda.ac.uk/uuid/77d63a69e3554412a40c9a9ba564e3f9
 
Description Geomagnetic Storm Timescales 
Organisation British Antarctic Survey
Country United Kingdom 
Sector Academic/University 
PI Contribution I performed simulations of the response of the Earth's ionosphere to changes in the solar wind during a geomagnetic storm. The results from these simulations were compared to ionospheric data from collaborators at the University of Southampton, and to ground magnetic field data from collaborators at the British Antarctic Survey. The resulting insights from the simulation helped to improve understanding of how the coupling between the solar wind and the Earth's magnetosphere results in severe space weather impacts, and what influences the timescales over which such impacts occur.
Collaborator Contribution The collaborators helped to identify an appropriate geomagnetic storm to be the focus of the study by searching through spacecraft data. Data analysis showing the response timescales of electric currents entering the Earth's ionosphere from the magnetosphere during the chosen storm was performed by collaborators at the University of Southampton, and similar analysis showing the response timescales of the ground magnetic field on the Earth's surface was performed by collaborators at the British Antarctic Survey.
Impact Poster presentation at the 2020 European Geosciences Union General Assembly: "Timescales of Ionospheric Field-Aligned Currents during a Geomagnetic Storm: Global Magnetospheric Simulations", DOI: 10.5194/egusphere-egu2020-16461
Start Year 2019
 
Description Geomagnetic Storm Timescales 
Organisation University of Southampton
Country United Kingdom 
Sector Academic/University 
PI Contribution I performed simulations of the response of the Earth's ionosphere to changes in the solar wind during a geomagnetic storm. The results from these simulations were compared to ionospheric data from collaborators at the University of Southampton, and to ground magnetic field data from collaborators at the British Antarctic Survey. The resulting insights from the simulation helped to improve understanding of how the coupling between the solar wind and the Earth's magnetosphere results in severe space weather impacts, and what influences the timescales over which such impacts occur.
Collaborator Contribution The collaborators helped to identify an appropriate geomagnetic storm to be the focus of the study by searching through spacecraft data. Data analysis showing the response timescales of electric currents entering the Earth's ionosphere from the magnetosphere during the chosen storm was performed by collaborators at the University of Southampton, and similar analysis showing the response timescales of the ground magnetic field on the Earth's surface was performed by collaborators at the British Antarctic Survey.
Impact Poster presentation at the 2020 European Geosciences Union General Assembly: "Timescales of Ionospheric Field-Aligned Currents during a Geomagnetic Storm: Global Magnetospheric Simulations", DOI: 10.5194/egusphere-egu2020-16461
Start Year 2019
 
Description Science Museum Summer of Space Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact I assisted on the 'Space Soundscapes' exhibit as a science expert. In this exhibit, members of the public listened to processed satellite data which turned low-frequency plasma waves in Earth's near-space environment into audible range frequencies, allowing them to hear the true 'sounds' of space. People wrote down descriptions of what they heard on post-it notes and attached these to a board which I was stood next to. I then answered any questions which members of the public had, and helped them to understand what they were hearing. The exhibit contributed to public understanding and interest in space science.
Year(s) Of Engagement Activity 2019