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C335: Building hillslope erosion and debris transport processes into glacier mass balance models (Lead Supervisor: Ian Willis, Scott Polar Research Institute)

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

Importance of the area of research:

Regional and global assessments of past and future glacier mass balance are heavily biased towards clean-ice glaciers. However, many glaciers, at least in part, are covered by debris ranging in thickness from millimetres to metres. As glaciers shrink, debris cover increases. Detailed studies on specific glaciers show that debris exerts an important influence on glacier melt (thin veneers enhance melt but thick blankets, which are increasingly more common, inhibit melt); this has important implications for glacier mass balance. Since regional and global predictions of glacier mass balance do not explicitly account for the role of debris, they may be overestimating their rate of disappearance. Large volumes of buried ice blanketed beneath thick debris may continue to exist for decades into the future, with important implications for local and regional water supply and for global sea level.

Project summary:

This project will, for a range of glaciers in both the European Alps and the Himalayas, incorporate hillslope erosion and debris transport processes into a distributed glacier surface mass balance – flow model. Key hillslope processes are rock falls and debris flows which deliver debris to glacier surfaces and are largely topographically and climatically driven. Debris is transported by glacier flow but its extent and thickness will change down-glacier and over time in response to patterns of velocity and strain rate. Our existing glacier surface mass balance – flow model uses either the energy balance or degree-day approach to calculate surface melt rates across largely clean-ice surfaces but will be modified to include the role of the debris.

What the student will do:

There are four main components. First, archived satellite imagery will be used to identify the magnitude and frequency of hillslope erosion processes and debris delivery to glacier surfaces. Topographic and climate data will be analysed to identify where and when major hillslope erosion processes occur and how sediment delivery is controlled. These data sets will be used to parameterise physically-based hillslope erosion and sediment delivery models.

Second, image correlation techniques will be used to identify glacier flow characteristics and their change over time. A combination of thermal band imagery and energy balance modelling will be used to map debris thickness and its change over time. Contemporary free imagery, and very high resolution commercial imagery, together with some targeted field campaigns will be used to validate these past debris cover reconstructions. The data sets will be used to parameterise a glacier debris thickness evolution model.

Third, the hillslope erosion and debris transport models will be embedded within our existing glacier mass balance – flow model and used to calculate past glacier and debris cover changes in catchments not used in the parameterisation stage above, tested against the available satellite-derived evidence.

Finally, the full coupled model will be run into the future, driven by modelled climatologies for the C21st.

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:

Miles, E.S., Pellicciotti, F., Willis, I.W., Steiner, J.F., Buri, P., & Arnold, N.S. (2016). Refined energy-balance modeling of a supraglacial pond, Langtang Khola, Nepal. Annals of Glaciology, 57(71): 29-40. doi: 10.3189/2016AoG71A421

Reid, T. D., M. Carenzo, F. Pellicciotti, and B. W. Brock (2012). Including debris cover effects in a distributed model of glacier ablation. J. Geophys. Res., 117, D18105, doi:10.1029/2012JD017795.

Rowan, A.V., D. L. Egholm, D. J. Quincey and N. F. Glasser. 2015. Modelling the feedbacks between mass balance, ice flow and debris transport to predict the response to climate change of debris-covered glaciers in the Himalaya. Earth and Planetary Science Letters. 11/2015; 430:427-438. DOI: 10.1016/j.epsl.2015.09.004

Follow this link to find out about applying for this project

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