PhD Study : Surface wind modelling on Mars

Summary

The modern surface of Mars has widespread substantial deposits of sand-sized sediments that form significant sand dune fields of various typologies and scales (Bridges et al. 2012). With wind forces being the only contemporary (and ancient) driving parameter in moving and altering dunefields and sediment processes across the surface of Mars, understanding the dynamics of surface atmospheric boundary layers in contact with the underlying sediment surface is paramount in any examination of the landform dynamics.

Most research efforts to date have focussed on Mars atmospheric circulation at very large scales, with Global Climate Models (GCMs) (e.g., Leovy and Mintz, 1969; Haberle et al., 1993; Hourdin et al., 1995; Richardson et al., 2002) being the primary guidance. The temporal and spatial scales these models are operating at are good first principles in understanding atmospheric-surface interactions –  however, they are much too coarse when we are trying to understand how surface landforms such as dunes are (or have been) moulded into the forms we see them in today.

Understanding aeolian (wind-blown) processes must be approached at a spatial scale of much less than the length of a dune to properly assess dune evolution patterns. Mesoscale climate models (e.g., Rafkin et al., 2001; Toigo and Richardson, 2002; Tyler et al., 2002; Richardson et al., 2007; Spiga and Forget, 2009) have reduced the resolution gap considerably, but their utility chiefly lies at the dunefield scale or larger. However, mesoscale modelling does capture relatively short-timescale wind flow pattern variability due to complex interactions between the atmosphere and regional topography and surface properties. Such variations are believed to be hugely important for localised modifications in dunefields and for the longer term dynamics of the dunes’ migration patterns.

Recent efforts (Jackson et al. 2015) have employed 3-D microscale (<5m resolution) computational fluid dynamics modelling to investigate atmospheric surface interactions and dune surface changes. Mars atmospheric/aeolian model validation can take many forms, but in the context of sand dunes, it typically involves analysing orbital imagery of the dunes and their surroundings to find relevant morphological changes and clues. Additionally, the Curiosity rover has recently passed through a small dunefield in Gale crater (Mars), providing invaluable in situ imagery and meteorological data. Several state-of-the-art numerical atmospheric modelling tools will be used, including a Mars GCM, a regional Mars mesoscale climate model, and a computational fluid dynamics model (OpenFOAM). Geospatial and geomorphic analysis of relevant spacecraft imagery and other observational data will be used to constrain and validate the modelling results.

Objectives:

Overall to combine macro- to meso- to micro-scale airflow modelling for a significantly more realistic approach to modelling the meter-scale fluid dynamics involved in the time-evolution of aeolian features (such as dunes) on Mars.

Specific objectives:

*Run the global climate model using contemporary Mars parameters, archiving its output for use as the initial state and boundary conditions for mesoscale modelling runs

*Select key sites to apply the integrated modelling approach at, favouring locations with exceptional orbital and/or in situ observational data coverage

*Access and analyse digital terrain models of the Martian surface, integrating them into mesoscale and microscale airflow model runs

*Merge mesoscale climate modelling with CFD microscale simulations through initial state and boundary conditions

*Validate the model results using geomorphic analysis of imagery and in situ datasets

References:

Bridges, N.T., Bourke, M.C., Geissler, P.E., Banks, M.E., Colon, C., Diniega, S., Golombek, M.P., Hansen, C.J., Mattson, S., McEwen, A.S., Mellon, M.T., Stantzos, N., and Thomson, B.J., 2012. Planet-wide sand motion on Mars, Geology, 40(1), 31-34.

Haberle, R.M., Pollack, J.B., Barnes, J.R., Zurek, R.W., Leovy, C.B., Murphy, J.R., Lee, H., and Schaeffer, J., 1993. Mars atmospheric dynamics as simulated by the NASA Ames General Circulation Model, 1. The zonal mean circulation. Journal of Geophysical Research, 98, 3093-3123.

Hourdin, F. and Forget, F., 1995. The sensitivity of the Martian surface pressure and atmospheric mass budget to various parameters: A comparison between numerical simulations and Viking observations. Journal of Geophysical Research, 100 (E3), 5501-5523, doi:10.1029/94JE03079.

Jackson, D.W.T., Bourke, M.C., and Smyth, T.A.G., 2015. The dune effect on sand-transporting winds on Mars. Nature Communications, 6:8796.

Leovy, C. and Mintz, Y., 1969. Numerical simulation of the atmospheric circulation and climate of Mars. Journal of Atmospheric Science, 26 (6), 1167-1190.

Rafkin, S.C.R., Haberle, R.M., and Michaels, T.I., 2001. The Mars Regional Atmospheric Modeling System: Model description and selected simulations. Icarus, 151, doi:10.1006/icar.2001.6605.

Richardson, M.I., Wilson, R.J., and Rodin, A.V., 2002. Water ice clouds in the Martian atmosphere: General circulation model experiments with a simple cloud scheme. Journal of Geophysical Research, 107 (E9), doi:10.1029/2001JE001804.

Richardson, M.I., Toigo, A.D., and Newman, C.E., 2007. PlanetWRF: A general purpose, local to global numerical model for planetary atmospheric and climate dynamics. Journal of Geophysical Research, 112 (E9), doi:10.1029/2006JE002825.

Spiga, A. and Forget, F., 2009. A new model to simulate the Martian mesoscale and microscale atmospheric circulation: Validation and first results. Journal of Geophysical Research, 114 (E2),  doi:10.1029/2008JE003242.

Toigo, A.D. and Richardson, M.I., 2002. A mesoscale model for the Martian atmosphere, Journal of Geophysical Research, 107 (E7), doi:10.1029/2000JE001489.

Tyler, D., Barnes, J.R., and Haberle, R.M., 2002. Simulation of surface meteorology at the Pathfinder and VL1 sites using a Mars mesoscale model. Journal of Geophysical Research, 107 (E4), doi:10.1029/2001JE001618.

Essential criteria

Applicants should hold, or expect to obtain, a First or Upper Second Class Honours Degree in a subject relevant to the proposed area of study.

We may also consider applications from those who hold equivalent qualifications, for example, a Lower Second Class Honours Degree plus a Master’s Degree with Distinction.

In exceptional circumstances, the University may consider a portfolio of evidence from applicants who have appropriate professional experience which is equivalent to the learning outcomes of an Honours degree in lieu of academic qualifications.

• A comprehensive and articulate personal statement

Desirable Criteria

If the University receives a large number of applicants for the project, the following desirable criteria may be applied to shortlist applicants for interview.

• First Class Honours (1st) Degree
• Masters at 65%
• Research project completion within taught Masters degree or MRES
• Experience using research methods or other approaches relevant to the subject domain
• Work experience relevant to the proposed project
• Experience of presentation of research findings

Funding and eligibility

The University offers the following levels of support:

Vice Chancellors Research Studentship (VCRS)

The following scholarship options are available to applicants worldwide:

• Full Award: (full-time tuition fees + £19,000 (tbc))
• Part Award: (full-time tuition fees + £9,500)
• Fees Only Award: (full-time tuition fees)

These scholarships will cover full-time PhD tuition fees for three years (subject to satisfactory academic performance) and will provide a £900 per annum research training support grant (RTSG) to help support the PhD researcher.

Applicants who already hold a doctoral degree or who have been registered on a programme of research leading to the award of a doctoral degree on a full-time basis for more than one year (or part-time equivalent) are NOT eligible to apply for an award.

Please note: you will automatically be entered into the competition for the Full Award, unless you state otherwise in your application.

Department for the Economy (DFE)

The scholarship will cover tuition fees at the Home rate and a maintenance allowance of £19,000 (tbc) per annum for three years (subject to satisfactory academic performance).

This scholarship also comes with £900 per annum for three years as a research training support grant (RTSG) allocation to help support the PhD researcher.

• Candidates with pre-settled or settled status under the EU Settlement Scheme, who also satisfy a three year residency requirement in the UK prior to the start of the course for which a Studentship is held MAY receive a Studentship covering fees and maintenance.
• Republic of Ireland (ROI) nationals who satisfy three years’ residency in the UK prior to the start of the course MAY receive a Studentship covering fees and maintenance (ROI nationals don’t need to have pre-settled or settled status under the EU Settlement Scheme to qualify).
• Other non-ROI EU applicants are ‘International’ are not eligible for this source of funding.
• Applicants who already hold a doctoral degree or who have been registered on a programme of research leading to the award of a doctoral degree on a full-time basis for more than one year (or part-time equivalent) are NOT eligible to apply for an award.

Due consideration should be given to financing your studies. Further information on cost of living