Improving estimates of Antarctic geothermal heat flow from geophysical data (GTA eligible project)

Description

The flow of heat coming from the Earth’s interior is an important parameter to consider when studying how ice sheets flow and deform. It also plays a key role in determining how the Earth’s crust rebounds upwards once ice mass is displaced, influencing our estimates of sea-level rise among others. It is very difficult to measure geothermal heat flow directly, particularly beneath the kilometer-thick ice sheets in Antarctica. As such, we often rely on indirect geophysical measurements to estimate heat flow on continental scales (Burton-Johnson et al., 2020). One of the main geophysical methods used for this purpose is magnetometry, the measurement of anomalies in the Earth’s magnetic field due to magnetized rocks in the crust. The magnetic anomaly data allows us to estimate the depth at which magnetic minerals reach a temperature that makes them lose their magnetic properties, known as the Curie isotherm (Fox Maule et al., 2005; Martos et al., 2017). This provides information about the temperature of the crust at depths of up to 60 kilometers. 

When estimating Curie isotherm depths from magnetic data, we tend to assume that 1) the crust is uniformly magnetized and 2) the magnetic data from different surveys can be merged into a single dataset without errors. On the scale of a continent, the magnetization of the crust is known to vary due to the lateral changes in the Earth’s magnetic field and the presence of remanent magnetization in crustal rocks from the time of their formation. The magnetic anomaly data are also dependent on the direction of the Earth’s core field at the time of acquisition. Since the Earth’s field changes over time, merging data from surveys conducted at different times can be problematic if this effect is not taken into account. Nonetheless, these assumptions are often required in practice due to incomplete information and a lack of better data processing methods. The errors introduced by these failed assumptions may leak into geothermal heat flow estimates and any predictions of ice sheet behaviour and sea-level rise that are based upon them.

In this project, our goals are to 1) quantify the effect of merging magnetic data from different surveys due to changes in the Earth’s magnetic field and crustal magnetization, 2) produce an integrated magnetic data compilation for Antarctica that is less dependent on the direction of the Earth’s field using state-of-the-art processing methods, and 3) estimate the depth to the Curie isotherm in Antarctica using the newly generated magnetic data. The magnetic data integration and Curie depth estimation will be done by adapting methods and software recently developed by the research group and our international collaborators (for example, Hidalgo-Gato et al., 2021, and Reis et al., 2020). By achieving these goals, we hope to quantify and reduce the uncertainty in the Curie isotherm depth estimates for Antarctica, which is a key parameter in determining geothermal heat flow (Lösing et al., 2020). 

The appointed student will acquire the mathematical and computer programming skills required to undertake the project. They will be trained to develop software in a collaborative environment using GitHub and the current best practices in research software engineering. The project will be conducted following the current established norms of open-science and reproducible research, with all outputs published on the group’s GitHub page (github.com/compgeolab). The project also has the potential to involve code contributions to the different open-source Python software developed by the research group, mainly Fatiando a Terra (www.fatiando.org), leading to potential impact beyond standard scientific publications. This position would suit someone with mathematical and numerical methods skills (or who is willing to learn). Some experience with computer programming in any language is desirable. 

This PhD topic is one of eight eligible for funding support through the recruitment of two Graduate Teaching Assistants within Geography & Planning and Earth Sciences at 0.5 FTE over a five-year period. The expectation is that no less than 50% of your time will be made available for the pursuit of your PhD or MPhil studies. In addition to your application for the PhD (detailed here), you are also required to apply for the 0.5 FTE University Teacher Salary: (£29,177 - £33,797 pa – at 0.5FTE pro rata) ensure that, in the funding section of the PGR application form, you mark your application ‘GTA SoES Post’. 

For any enquiries please contact, Dr. Leonardo Uieda on: 

To apply for this opportunity, please visit: https://www.liverpool.ac.uk/study/postgraduate-research/how-to-apply/

Availability

Open to UK applicants

Funding information

Funded studentship

Funding for the PhD includes tuition fees and a research support budget £1,000 per year.

Supervisors

References

Burton-Johnson, A., Dziadek, R., & Martin, C. (2020). Review article: Geothermal heat flow in Antarctica: current and future directions. The Cryosphere, 14(11), 3843–3873. https://doi.org/10.5194/tc-14-3843-2020
Hidalgo-Gato, M. C., Barbosa, V. C. F., & Oliveira, V. C., Jr. (2021). Magnetic amplitude inversion for depth-to-basement and apparent magnetization-intensity estimates. GEOPHYSICS, 86(1), J1–J11. https://doi.org/10.1190/geo2019-0726.1
Lösing, M., Ebbing, J., & Szwillus, W. (2020). Geothermal Heat Flux in Antarctica: Assessing Models and Observations by Bayesian Inversion. Frontiers in Earth Science, 8. https://doi.org/10.3389/feart.2020.00105
Martos, Y. M., Catalán, M., Jordan, T. A., Golynsky, A., Golynsky, D., Eagles, G., & Vaughan, D. G. (2017). Heat Flux Distribution of Antarctica Unveiled. Geophysical Research Letters, 44(22), 11,417-11,426. https://doi.org/10.1002/2017gl075609
Fox Maule, C., Purucker, M.E., Olsen, N., Mosengaard, K. (2005). Heat Flux Anomalies in Antarctica Revealed by Satellite Magnetic Data. Science, 309(5733), 464–467. https://doi.org/10.1126/science.1106888
Reis, A. L. A., Oliveira Jr., V. C., & Barbosa, V. C. F. (2020). Generalized positivity constraint on magnetic equivalent layers. GEOPHYSICS, 85(6), J99–J110. https://doi.org/10.1190/geo2019-0706.1