CR2025_28 Ice sheets and glaciers in a warming climate: measuring and modelling surface melt lakes

Lead Supervisor: Bernd Kulessa, Department of Geography, Swansea University

Email: b.kulessa@swansea.ac.uk

Co-supervisors: Danny Feltham, Department of Meteorology, University of Reading; Sammie Buzzard, Northumbria University and Centre for Polar Observation and Modelling.

Surface melt lakes are ubiquitous on the Greenland Ice Sheet (Fig. 1), on Antarctica ice shelves and on mountain glaciers worldwide, and their global abundance will multiply further in a warming climate. This matters because their sudden, chain-reaction drainage is strongly implicated in the explosive break-up of Antarctic ice shelves, triggering substantial increases in ice discharge into the Southern Ocean, and therefore sea-level rise. In Greenland, thousands of surface lakes develop every melt season around the ice-sheet’s margin which is important for three main reasons. First, melt lakes lower the reflectivity (albedo) of the surface, triggering enhanced absorption of radiation and further melting. Second, many such lakes drain suddenly and rapidly (often within minutes) to the ice-sheet bed, with cumulative lake drainages having substantial impacts on seasonal ice-flow speeds. Third, together they also represent important temporary stores that delay meltwater runoff into the ocean. On mountain glaciers, and prominently so in the Himalayan region, glacial lake formation and outburst floods present major and indeed growing hazards to downstream communities. It is therefore clear that we must understand the hydrological processes by which such surface lakes form and expand in a warming climate, but it is here where a major problem arises: we neither understand these processes well, nor are we able to model these processes and their evolution in a warming climate.

This PhD project aims to test, and appropriately improve, a world-leading existing model of surface melt lake development using novel geophysical data sets collected on the Juneau Icefield in Alaska. Drone-based ground-penetrating radar measurements will map the shallow snow, firn and englacial ice structure around a site where a surface melt lake is known to develop every meltseason. Electrical self-potential measurements will map and monitor meltwater flows through snow, firn and the surface-ice weathering crust as the lake evolves, a key uncertainty in understanding surface hydrology. These geophysical data sets will be complemented by in situ lake and shallow englacial temperature measurements, as well as those of lake water levels, and a met station established on the icefield. The combined data set will be ideally suited to test, initially, an established 1-D model of surface lake development. The model numerically solves coupled systems of differential equations describing the surface energy balance, heat transfer through the firn, the production and percolation of meltwater into the firn, the formation of ice lenses, and the development and refreezing of melt lakes. An exciting opportunity then exists to expand the data-constrained modelling experiments to test MONARCHS, a hot-of-the-press community-driven, open-access surface hydrology model. This next-generation model incorporates a full representation of 3-D processes such as lateral transport of surface meltwater, which is naturally restricted in existing 1-D models.

This PhD project is globally pioneering in that it will be the first time that a surface melt lake model will be tested and calibrated with a fully comprehensive suite of measurements. This will be particularly significant due to the field data being acquired at a mountain icefield location where climate warming has been particularly pronounced. Depending on the interests of the student, focus can be placed on field measurements or improved representation of physical processes in the model or, of course, a combination of both. The student will join an international, multi-disciplinary team of students and scientists that work together every year as part of the Juneau Icefield Research Program – a fantastic opportunity to not only conduct world-class and fun science, but also meet like-minded colleagues from around the globe and acquire a plethora of new skills. Better incorporation of data into ice-sheet models, and glaciological models more widely, is at the frontier of modern glaciology: this PhD project offers the opportunity to acquire important and exciting nextgeneration skills.

Training opportunities: 

• Drone science, holding untold potential in glaciological exploration.
• The electrical self-potential geophysical method, with unique ability to sense meltwater flows through snow, firn and ice.
• Learn directly from the developers of world-leading melt lake models and their integration into the Joint UK Land Environment Simulator (JULES).
• Juneau Icefield Research Program: meet many like-minded scientists from around the globe and acquire multi-disciplinary skills.
• Join the Centre for Polar Observation and Modelling community across multiple HEIs and the British Antarctic Survey.
• Apply to the Karthaus Summer School on Ice Sheets and Glaciers in the Climate System. 

Student profile: 

• Strongly numerate, and ideally also with evident skills in data collection and practical problemsolving.
• Physics, applied mathematics, geophysics or other strongly quantitative geoscientific discipline (e.g., meteorology, oceanography), appropriate engineering subject (e.g., environmental, fluid dynamics, civil).

Co-Sponsorship details: 

This project will receive co-sponsorship from the University of Maine. This will be through logistics support for field survey program through the Juneau Icefield Research Program. 

References:

• www1: https://juneauicefield.org/ www2: https://www.malagpr.com.au/uploads/3/7/9/4/37942849/quick_guide_geodrone80_v1.pdf
• Priestley, A., Kulessa, B., Essery, R., Lejeune, Y., Le Gac, E., & Blackford, J. (2022). Towards the development of an automated electrical self-potential sensor of melt and rainwater flow in snow. Journal of Glaciology, 68(270), 720-732. https://doi.org/10.1017/jog.2021.128
• The Firn Symposium team. Firn on ice sheets. Nat Rev Earth Environ 5, 79–99 (2024). https://doi.org/10.1038/s43017-023-00507-9
• Buzzard, S. C., Feltham, D. L., & Flocco, D. (2018). A Mathematical Model of Melt Lake Development on an Ice Shelf. Journal of Advances in Modeling Earth Systems, 10(2), 262-283. https://doi.org/10.1002/2017ms001155
• Buzzard, S., Robel, A., & MacAyeal, D. (2023). Modelling Ice Shelf Hydrology and Flexure in
• Response to Meltwater Loading. AGU Fall Meeting Abstracts, https://ui.adsabs.harvard.edu/abs/2023AGUFM.C52A..06B/abstract