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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities

Lead Supervisor: Amelie Kirchgaessner, British Antarctic Survey

Co-Supervisor: Ian Willis, Scott Polar Research Institute (based in Geography); Andrew Orr, British Antarctic Survey & Neil Arnold, Scott Polar Research Institute (based in Geography)

Brief summary: 
Investigate what causes surface melt on George VI Ice Shelf, Antarctica by combining high-resolution climate simulations with state of the art remote sensing techniques!
Importance of the area of research concerned: 
The floating ice shelves around Antarctica provide a buffer against rapid ice flow from the continent's interior to the ocean. If that buffer is reduced or removed, the ice flow towards the ocean will accelerate. Unlike the ice shelves themselves, this ice flow will contribute to global sea level rise. It is therefore important to understand the controls on ice shelf stability, to assess and predict a possible future ice shelf collapse. Evidence shows that one source of ice shelf instability comes from surface melting and the movement of the meltwater. This project complements current research of the supervisor team on: (1) climate patterns and their variability over the Antarctic Peninsula (AP); (2) melt water ponding on Antarctic ice shelves; and (3) the viscoelastic ice-shelf flexure and fracture that are observed in response to surface melt water ponding and movement.
Project summary : 
High resolution atmospheric simulations will be combined with the satellite-derived estimates of surface melt in the area of George VI Ice Shelf (GVIIS) on the AP to investigate the atmospheric drivers for this surface melt. Adiabatic warming in the lee of mountains (föhn) has been found to be a key driver behind surface melt over the Larsen Ice Shelf. The orography around GVIIS is conducive to föhn winds, and other orographically forced flow regimes. This project will investigate: - The frequency of föhn and other distinct atmospheric flow regimes over GVIIS - Their impact on the surface energy balance of GVIIS - How these findings match with satellite-derived estimates of surface melt on GVIIS - How the frequency of the flow regimes may change under future climate scenarios - How such changes may influence the surface energy balance, and hence melt, on GVIIS throughout the C21st
What will the student do?: 
The student will run high-resolution simulations for 2000 – 2019, and analyse them for atmospheric flow regimes based on their meteorological signature. Model output of radiative and turbulent fluxes at and near the surface will be used to investigate the impact of föhn on the local surface energy balance. The presence and extent of melt water on GVIIS during the same period will be investigated using optical and synthetic-aperture radar satellite imagery. The extent and volume of melt ponds, and of water-saturated snow or firn (slush) will be investigated using established thresholding and classification schemes, including machine learning. These results will be compared with the atmospheric simulations to investigate possible drivers of melt events. The student will then run high-resolution simulations for future emission scenarios (2020-2040) to investigate changes in frequency and occurrence of flow regimes. CMIP6 projections will be used as boundary conditions for these simulations. The analysis of the historical simulations and melt extent will allow future melt patterns on the ice shelf to be modelled, and the medium-term stability of the ice shelf to be assessed.
References - references should provide further reading about the project: 
Kirchgaessner, A., King, J., & Gadian, A. 2019. The representation of Föhn events to the east of the Antarctic Peninsula in simulations by the Antarctic Mesoscale Prediction System. Journal of Geophysical Research: Atmospheres, 124, 13663– 13679.
Dell, R., Arnold, N., Willis, I., Banwell, A., Williamson, A., Pritchard, H. and Orr, A, 2020. Lateral meltwater transfer across an Antarctic ice shelf. The Cryosphere, p.1-24. doi:10.5194/tc-2019-316
Banwell, A.F., Willis, I.C., Macdonald, G.J., Goodsell, B. and MacAyeal, D.R., 2019. Direct measurements of ice-shelf flexure caused by surface meltwater ponding and drainage. Nat Commun, v. 10, p.730- doi:10.1038/s41467-019-08522-5.
Dr Amelie Kirchgaessner
Dr Andrew Orr
British Antarctic Survey Graduate Administrator
Dr Neil Arnold
Dr Ian Willis