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C418: Exploring hydrological systems beneath the Greenland Ice Sheet using high precision radar (Lead Supervisor: Keith Nicholls, British Antarctic Survey)

Supervisors: Keith Nicholls (British Antarctic Survey) and Poul Christoffersen (SPRI)

Importance of the area of research:

The Greenland Ice Sheets continues to lose mass through increased surface melting, and from the acceleration of fast-flowing glaciers that terminate in coastal fjords. Retreat of grounding lines as a result of glacier thinning, and a more rapid discharge of ice from the ice sheet into the ocean, has profound consequences both for the oceanography of this ecologically rich region, and for rising sea levels.

Water flow and melting at the base of the glaciers influences the ice motion over the bed, and so drainage through the ice sheet exerts fundamental control on ice sheet dynamics. However, the study of sub-glacial hydrology and how it relates to the hydrological system on the glacier surface has historically been very challenging. The development of high precision radar systems capable of imaging glacier beds with millimeter precision provides an opportunity to develop a better understanding of ice sheet hydrology. Only by exploiting new technologies such as these will it be possible to make significant progress in understanding the dependence of glacier motion on surface mass balance, and ultimately learn how to predict the future of the Greenland Ice Sheet.

Project summary:

The aim of the project is to use novel radar techniques to study water conduits in and below fast-flowing Greenland glaciers. Precise, downward-looking, phase-sensitive radars will be deployed on Store Greenland in West Greenland. By making measurements over a broad area, a synthetic aperture will be created, allowing the imaging of the glacier interior and base. The radar will be left year-round, using multiple antennas to create the aperture, capturing data every few hours.

The imagery will be processed and analysed to determine how water is routed at the base of the glacier and thus how the glacier’s hydrology responds to seasonal penetration of meltwater from the surface. Ancillary datasets of glacier velocity and visual imagery will be used to determine the glacier response to the seasonal hydrological forcing. Results from a trial will be available at the start of the project.

What the student will do:

The student will be responsible for assembling the antenna array, and preparing and testing the phase-sensitive radar instruments. It is anticipated that s/he will undertake a minimum of two field seasons as part of a larger team of Cambridge scientists studying Store Glacier with funding from the European Research Council (www.erc-responder.eu). Transportation to the field site will be by helicopter. The student, who will be responsible for the deployment of autonomous radar instruments, would live in a science camp set up on the ice sheet.

Initial data processing will be done using established methods. The student will then use synthetic aperture processing techniques to determine the evolution of the basal hydrology during the year, and then relate this to ancillary datasets gathered through exploratory boreholes drilled in the vicinity of the deployed radar instrument in order to observe the basal environment directly.

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:

Howat, I. M., de la Pena, S., van Angelen, J. H., Lenaerts, J. T. M. & van den Broeke, M. R. 2013. Expansion of meltwater lakes on the Greenland Ice Sheet. Cryosphere 7, 201-204, doi:10.5194/tc-7-201-2013.

Marsh, O.J., Fricker, H.A., Siegfried, M.R., Christianson, K., Nicholls, K.W., Corr, H.F.J. and Catania, G. 2016. High basal melting forming a channel at the grounding line of Ross Ice Shelf, Antarctica. Geophysical Research Letters, 43(1): 250-255,10.1002/2015gl066612.

Nicholls, Keith W., Corr, Hugh F.J., Stewart, Craig L., Lok, Lai Bun, Brennan, Paul V., Vaughan, David G (2015), A ground-based radar for measuring vertical strain rates and time-varying basal melt rates in ice sheets and shelves. Journal of Glaciology, 61. 1079-1087. doi:10.3189/2015JoG15J073.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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