Cyclones and their influence on Greenland ice sheet surface mass balance and dynamics through satellite remote sensing and modelling

The Greenland Ice Sheet (GrIS) has the potential to raise global sea level by approximately 7 m, if it were to melt completely, yet the processes that determine its contribution to sea level rise over time are not well understood. Mass is lost from the ice sheet primarily due to changes surface mass balance (SMB) and ice dynamics. Understanding the complex processes involved in determining the change in these over time creates a challenge for estimating the current and future contribution of the GrIS to sea level. There is limited research on the role of extratropical cyclones in forcing variations in surface mass balance and ice dynamics, however, work to date suggests that their passage during summer can initiate periods of intense melting and can locally accelerate ice flow (Doyle et al., 2015; McLeod and Mote, 2015). The extent to which these controls extend across the ice sheet, and as the climate continues to warm, is yet to be determined and with climate models projecting an increase in frequency of cyclones over the 21st Century this presents a key area for further research. Therefore, this project will explore in detail the impacts of past cyclonic weather events on variability in GrIS SMB and ice dynamics in order to increase our understanding of the current and future response of the GrIS to climate change.

The impacts of past cyclones on the GrIS will be assessed using an array of data from satellite observations and numerical models (of the atmosphere and ice sheet). Satellite datasets will be used primarily to produce ice velocity estimates and terminus retreat/advance information, however, other important parameters will also be calculated (e.g. albedo, water presence in the snow pack). Numerical model data will be employed to assess the surface energy and mass balance response to cyclonic forcing, and also to explore the role of air mass advection and modification in controlling this behaviour. Building on these insights, climate model projections from CMIP5/CMIP6 will be used to probe the possible implications of enhanced future cyclonicity for GrIS mass loss.

The project aim is to improve understanding of extratropical cyclone forcing on Greenland Ice Sheet (GrIS) surface mass balance and ice dynamics and through this determine the impact on future contribution of the GrIS to sea level as cyclonic activity increases over the ice sheet.

There may be an opportunity for the successful candidate to travel to Denmark during the PhD to meet with collaborators on the project.

The PhD candidate will need to be in place for a start date no later than 1st November 2017.

Entry Requirements:

The applicant should be from the UK/EU only and have some familiarity with satellite remote sensing and/or computer programming with an interest in the cryosphere. The successful candidate should have, or expect to have, at least an Honours Degree at 2.1 or above (or equivalent) in environmental/geographical science or another numerate technical discipline, although an MSc would be preferred.

Key references:

Doyle et al. (2015) ‘Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall’. Nature Geoscience, 8, 647- 656, DOI: 10.1038/NGEO2482

McLeod, J.T. and Mote, T.L., (2015) ‘Assessing the role of precursor cyclones on the formation of extreme Greenland blocking episodes and their impact on summer melting across the Greenland ice sheet’. Journal of Geophysical Research: Atmospheres, 120(24), 12357-12377.