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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 
Brief summary: 
Antarctic ice shelves are vital for the stability of the Antarctic Ice Sheet, but are increasingly being affected by surface melting which can ultimately cause ice shelf collapse.
Importance of the area of research concerned: 
Processes of water production, infiltration, ponding, refreezing and flow on Antarctic Ice Shelves are poorly understood but have important implications for ice shelf mass balance, runoff, ice flexure, and potentially fracture and break up. If meltwater collects in surface lakes it may weaken an ice shelf facilitating its breakup. Alternatively, if large stream networks develop, surface melt may be evacuated to the ice shelf edge, reducing the potential for break up. Less is known about water stored within the snow or firn. Field measurements have found extensive contemporary firn water aquifers, and also point to large frozen ice lenses as evidence of former water aquifers. Although physically-based meltwater infiltration models have been used to calculate vertical firn water flow and refreezing, showing that years with extensive surface melt and subsurface refreezing may lead to greater ponding above impermeable ice layers in subsequent years, models dealing with horizontal advection of surface and subsurface water, and storage/ refreezing/ draining in lakes and firn aquifers on Antarctic ice shelves are less well developed and applied.
Project summary : 
The project will develop a numerical model to calculate both vertical and horizontal meltwater movement, refreezing and runoff for ice shelves. Previously, together with former students at SPRI, we have separately modelled: i) vertical energy and mass transfer processes in snow/firn (water infiltration, refreezing of water, latent heat release, ice layer formation); and ii) horizontal mass transfer processes (surface channel flow and shallow subsurface porewater flow) to address different research questions on Svalbard glaciers and part of the Greenland Ice Sheet respectively. This project will take aspects of both models, incorporate other physical processes relevant to water flow on ice shelves, and produce a coupled 3-D surface and shallow subsurface energy / mass transfer model. Existing data sets produced at SPRI from satellite images will be used to validate the model.
What will the student do?: 
The student will use recent literature to identify all relevant hydrological processes occurring on different parts of various ice shelves across Antarctica. In addition, the student will identify all relevant process-based models that are in use to model snow / glacier hydrology. The student will identify the best modelling framework to use for modelling the relevant hydrological processes occurring on ice shelves, and develop code linking existing models for horizontal and vertical water movement. The model will be driven using past and future regional climate model output which the student will extract from online databases of current regional and global model results. The student will perform the model validation for the past using satellite-derived distributions of surface water (produced as part of a recently completed PhD student project) and satellite-derived distributions of subsurface water (produced as part of a current postdoctoral fellowship project); and they will run for future predictions for C21st patterns of surface and subsurface hydrology of ice shelves in order to assess the implications for future ice shelf stability.
References - references should provide further reading about the project: 
Bell, R. E., Banwell, A. F., Trusel, L. D., and Kingslake, J.: Antarctic surface hydrology and impacts on ice-sheet mass balance, Nature Climate Change, 8, 1044–1052, https://doi.org/10.1038/s41558-018-0326-3, http://www.nature.com/articles/s41558-018-0326-3, 2018.
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, v. 14, p.2313-2330. doi:10.5194/tc-14-2313-2020
Law, R., Arnold, N., Benedek, C., Tedesco, M., Banwell, A. and Willis, I., 2020. Over-winter persistence of supraglacial lakes on the Greenland Ice Sheet: Results and insights from a new model. Journal of Glaciology, v. 66, p.362-372. doi:10.1017/jog.2020.7.
Applying
You can find out about applying for this project on the Scott Polar Research Institute page.
Department of Geography Graduate Administrator
Dr Neil Arnold
Dr Ian Willis