A New Generation of Forward and Inverse Geodynamo Models
Lead Research Organisation:
University of Leeds
Department Name: School of Earth and Environment
Abstract
Have you ever wondered why compasses point north? This fundamental question, still unsolved, has perplexed many scientists including the likes of Einstein. Scientists now accept that the source of the geomagnetic field lies inside Earth's core and, like a giant bar magnet thousands of miles beneath our feet, radiates tentacle-like magnetic field lines that penetrate the mantle and wrap around the Earth. Although it is apparent that, at the Earth's surface, the geomagnetic field is principally dipolar (having north and south poles), images of the field at the edge of the core show many more complex features. Furthermore, the geomagnetic field varies slowly with time. Although over the duration of a human lifetime these changes are small, geologists have shown that, over the course of the Earth's history, the geomagnetic field globally reverses: the north and south poles swap places a few times every million years or so. The geomagnetic field is not only crucial for navigation (by many animals, as well as humans) but provides us with an electromagnetic shield that protects our planet from harmful solar and interstellar radiation, and consequently has a potentially important influence on climate. Of particular interest is the recent evidence that the Earth's dipolar field is losing strength and that it may completely reverse within 2000 years. During reversals the electromagnetic shield is significantly weakened and, although our ancestors have survived many such events apparently without harm, it is unknown how the many satellites and other technological infrastructure, that our society relies upon, will be affected. A full understanding of the generation of the Earth's magnetic field and its reversals would undoubtedly help us to limit any destructive effects that might occur. The geomagnetic field is generated by the so-called geodynamo mechanism, powered by motions of molten iron in the Earth's core. Scientists study the geodynamo by using complex computer models that simulate the processes in the core. However, because of severe computational difficulties inherent in current techniques, the physical properties of the modelled Earth must be altered in order to make the problem solvable on present-day computers. It is not possible to faithfully simulate the Earth's core, and opinion remains divided over the many interpretations of such geodynamo models, including the trigger for global reversals. An additional technique is to use observations of the magnetic field on Earth's surface to image the field and the structure of the flow of molten iron at the edge of the core. This has been enormously successful in revealing many interesting dynamics although, rather like attempting to understand the internal currents of the world's oceans by simply inspecting the ocean surface, it is impossible to say very much about the processes inside the core. Consequently, many aspects of the Earth's interior and source of the geomagnetic field remain a mystery. Earlier this year in an exciting new development, I presented some crucial theoretical advances that pave the way for constructing a new generation of geodynamo models. The new technique supplies a fundamentally new approach that allows realistic properties of the core to be accessed directly on computers, and I will be able to produce the first geodynamo models able to simulate the Earth's core accurately. This will enable robust characterisation of the mechanism that generates the geomagnetic field and detailed analysis of the associated phenomena, including magnetic reversals. Additionally, by further exploitation of the new theoretical developments, I will be able to use observations to probe the present-day magnetic field structure inside the core, again something that has never before been possible. These two complementary projects will revolutionise the state-of-the-art in geodynamo modelling and will provide unprecedented insights into the dynamics of the Earth's core.
Organisations
People |
ORCID iD |
Philip William Livermore (Principal Investigator) |
Publications
Brown W
(2013)
Jerks abound: An analysis of geomagnetic observatory data from 1957 to 2008
in Physics of the Earth and Planetary Interiors
Cox G
(2014)
Forward models of torsional waves: dispersion and geometric effects
in Geophysical Journal International
Cox G
(2019)
Penetration of boundary-driven flows into a rotating spherical thermally stratified fluid
in Journal of Fluid Mechanics
Fournier A
(2015)
The impact of geomagnetic spikes on the production rates of cosmogenic 14 C and 10 Be in the Earth's atmosphere
in Geophysical Research Letters
Hardy C
(2022)
The inherent instability of axisymmetric magnetostrophic dynamo models
in Geophysical & Astrophysical Fluid Dynamics
Hardy CM
(2018)
Determination of the instantaneous geostrophic flow within the three-dimensional magnetostrophic regime.
in Proceedings. Mathematical, physical, and engineering sciences
Jackson A
(2011)
On Ohmic heating in the Earth's core II: Poloidal magnetic fields obeying Taylor's constraint
in Physics of the Earth and Planetary Interiors
Jackson A
(2009)
On Ohmic heating in the Earth's core I: nutation constraints
in Geophysical Journal International
Description | All models describing the dynamics of Earth's core use a viscosity that is about a billion times too large, artificially enhancing its negligibly small effect. This fellowship was focussed on exploring the dynamics with zero viscosity. I found that it was possible to construct models with zero viscosity, and that models with very low (but non-zero) viscosity can behave quite differently from those with large viscosity. I used a model with unprecedentedly low viscosity to explain the rotation of the solid inner core. I also used a constraint required by viscosity-free models to explore snapshot models of the magnetic field inside the Earth's core, currently hidden from view. |
Exploitation Route | My research lays some of the groundwork for constructing more complex and dynamically self-consistent models of the Earth's core. My work predicts the existence of a jet inside the Earth's core (on the tangent cylinder), which was published in Nature Geoscience in 2017. Such a signature can either be sought in future observations, or in numerical simulations that are created in an international endeavour to study the Earth's core. |
Sectors | Education,Environment |
Description | My findings have been reported in talks to the general public and to schoolchildren. |
First Year Of Impact | 2009 |
Sector | Education,Environment |
Impact Types | Societal |
Title | Galerkin polynomials |
Description | A compendium of a variety of numerical methods known as Galerkin polynomials. |
Type Of Material | Computer model/algorithm |
Year Produced | 2009 |
Provided To Others? | Yes |
Impact | N/A |
URL | http://homepages.see.leeds.ac.uk/~earpwl/Galerkin/Galerkin.html |
Description | BBC radio interviews |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Based on some recent research (High-latitude Jets in Earth's core) I was interviewed on BBC radio world service and BBC radio Wales. The Jets are also planned to feature in a Japanese-funded Earth Science documentary. |
Year(s) Of Engagement Activity | 2017 |
Description | Interview for BBC world service and other international media |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | After presenting a talk at the annual American Geosciences Union conference about the north magnetic pole, there was a lot of media interest: radio shows, websites and printed newspapers. |
Year(s) Of Engagement Activity | 2019 |
Description | Interviewed in BBC programme The Curious Cases of Rutherford & Fry |
Form Of Engagement Activity | A broadcast e.g. TV/radio/film/podcast (other than news/press) |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | I was interviewed in a podcast for the BBC programme The Curious Cases of Rutherford & Fry - on global geomagnetic reversals. |
Year(s) Of Engagement Activity | 2017 |
Description | Interviews and media coverage covering research activity |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Multiple press releases and radio interviews (BBC radio Wales, BBC world service) based on the outcomes of a research article. The research was also featured in a Japanese documentary about the Earth's core and the geomagnetic field. |
Year(s) Of Engagement Activity | 2017 |
Description | Irish radio programme |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | I was interviewed in Newstalk, an Irish radio programme, about the deep Earth and specifically new research. N/A |
Year(s) Of Engagement Activity | 2013 |
Description | Leeds Festival of Science activity |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | Yes |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | I organised a workshop session for school children as part of the Leeds Festival of Science - this involved various aspects of the geomagnetic field and hands-on magnetic experiments. I sparked interest is the students for physical sciences. |
Year(s) Of Engagement Activity | 2012,2013,2014 |
Description | Outreach article for "The Conversation" |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | I coauthored a piece on geomagnetic reversals for "The Conversation", which has been read internationally by about 1.6 million people. |
Year(s) Of Engagement Activity | 2017 |
URL | http://theconversation.com/why-the-earths-magnetic-poles-could-be-about-to-swap-places-and-how-it-wo... |
Description | Predicting deep Earth processes and impacts on space climate |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | A 2-day workshop to discuss UK science in space climate change. Inclusion of the results of the workshop within the "UK space weather strategy" and article in Astronomy & Geophysics. |
Year(s) Of Engagement Activity | 2012 |
Description | Radio Slovenia |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | I was interviewed on Radio Slovenia about the Earth's magnetic field. N/A |
Year(s) Of Engagement Activity | 2010 |
Description | SEDI conference |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | 5 days of scientific presentations. We put on a public talk "Journey to the centre of the Earth" |
Year(s) Of Engagement Activity | 2012 |
URL | http://www.see.leeds.ac.uk/research/igt/deep-earth-research/sedi-2012/ |
Description | UK SEDI |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Participants in your research and patient groups |
Results and Impact | A general discussion at the end of a day of scientific talks sparked questions from experienced researchers and PhD students. N/A |
Year(s) Of Engagement Activity | 2014 |
URL | http://www.see.leeds.ac.uk/research/igt/deep-earth-research/uksedi-2014/ |