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C336: Melting, ponding and refreezing on Antarctic ice shelves (Lead Supervisor: Ian Willis, Scott Polar Research Institute)

Supervisors: Ian Willis (Scott Polar Research Institute), Alison Banwell (Scott Polar Research Institute) and Neil Arnold (Scott Polar Research Institute)

Importance of the area of research:

The most likely way for the Antarctic Ice Sheet to contribute to sea level rise over the coming centuries involves the breakup of its ice shelves allowing faster inland ice discharge to the ocean (Shepherd et al, 2003). What is known about ice-shelf break-up comes from the few examples that have occurred over the past two decades along the Antarctic Peninsula. The explosive disintegration of the Larsen B Ice Shelf was attributed to the rise of melt-season duration and intensity that led to a widespread coverage of the ice shelf by ~ 2500 surface lakes, which persisted through the years leading up to the break-up in 2002 (Glasser and Scambos, 2008). In the days prior to ice-shelf’s disintegration, almost all the lakes were observed to drain, suggesting that hydrofracture and elastic flexure in response to lake-load changes were responsible for breaking it up into an uncountable melange of small icebergs that were easily able to capsize  and disperse (Banwell et al, 2013). Despite the established view that surface melt and lakes constitute important drivers of ice-shelf instability, the detailed processes of surface melt, vertical and lateral water movement, lake formation and refreezing on floating ice shelves remain largely unknown.

Project summary:

This project will, for a range of contrasting ice shelves around Antarctica, use a combination of existing field data, airborne and satellite remote sensing data, and numerical modelling to investigate the surface hydrology of ice shelves. Key processes to be studied are the energy exchange at the ice-shelf surface; melting; vertical and lateral movement of meltwater within and across the snow, firn and ice surfaces; the ponding of water in crevasses and surface depressions, and the possible feedback processes this may promote via surface albedo, energy exchange and conduction, leading to further melting; refreezing within snow/firn or on ice surfaces, and the possible feedback processes this may induce by providing impermeable layers, allowing further ponding.

What the student will do:

There are two aspects. First, the student will compile and analyse a suite of existing data sets (notably airborne and satellite data) for the last decade over selected ice shelves which, from preliminary inspection, show evidence of melting and ponding and variability from year to year. Both optical (visible and near infrared), thermal, and radar data will be used. These will be supplemented, where possible, by ground measurements (e.g. data collected in 2015/16 and 2016/17 on McMurdo ice shelf by the supervisors).

Second, the student will adapt existing surface energy balance, melt, refreezing, and water routing code (Arnold et al, 2014), which will be used to model the hydrological processes across the selected ice shelves. The above data sets will be used to both calibrate and validate the model. The key output from the research will be a better understanding of the hydrology of ice shelves, and a model which may be used to predict ice shelf hydrology into the future which will inform scientists about shelves which may be most prone to future breakup.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Arnold, N.S., Banwell, A.F. and Willis, I.C., 2014. High-resolution modelling of the seasonal evolution of surface water storage on the Greenland Ice Sheet. Cryosphere, v. 8, p.1149-1160. doi:10.5194/tc-8-1149-2014.

Banwell, A.F., Macayeal, D.R. & Sergienko, O.V. 2013. Breakup of the Larsen B Ice Shelf triggered by chain reaction drainage of supraglacial lakes. Geophysical Research Letters, 40, 10.1002/2013GL057694.

Glasser, N.F. & Scambos, T.A. 2008. A structural glaciological analysis of the 2002 Larsen Ice Shelf collapse. Journal of Glaciology, 54, 10.3189/002214308784409017.


Shepherd, A., Wingham, D., Payne,T. & Skvarca, P. 2003. Larsen Ice Shelf  has  progressively thinned. Science, 302,  doi:10.1126/science.1089768.

Follow this link to find out about applying for this project

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