NERC GW4+ DTP PhD studentship: Modelling Antarctic winds and ice flow, in order to connect geomorphology and the history of the West Antarctic Ice Sheet

University of Exeter - College of Life and Environmental Science

Main supervisor: Dr Anne Le Brocq (Geography, University of Exeter)

Geomorphological evidence in the Ellsworth Mountains, Antarctica suggests that the central divide of the West Antarctic Ice Sheet (WAIS) has been intact for at least the last 1.4 million years (Hein et al., 2016). This implies that the maximum global sea level contribution from the WAIS over multiple glacial-interglacial cycles is only around 3 m, not the potential 5 m contained in the whole ice sheet. Understanding the behaviour of the ice sheet in the past can give us an insight into how it may respond in the future to similar climate conditions.

The evidence comes from the presence of blue-ice moraines (Fig. 1), which are made up of rock material drawn up to the surface of the ice sheet from its base by an upward flow of ice. The upward flow of ice is to compensate for the wind-driven removal of snow at the ice sheet surface, which causes an imbalance in the snow input across the local ice surface. The wind-driven removal of snow results from strong katabatic winds blowing downslope off the ice sheet, inferring that some configuration of the WAIS must have been in place to enable this.

The conclusion of Hein et al. (2016) is based on the assumption that a smaller ice sheet located at the present ice divide is enough to still generate the katabatic winds, and hence, generate the moraines. However, the dependence of the strength of the downslope winds, and subsequent formation of the moraines, on the topographic configuration of the ice sheet is poorly understood. The proportion of the ice sheet which needs to remain intact to generate sufficiently strong winds is not known. Further, the strength of the wind that is required to cause sufficient ablation to form the moraine is also uncertain. There is, therefore, a strong need to increase our knowledge around the formation of downslope winds and the moraines, in order to connect the geomorphological evidence with the behaviour of the ice sheet in the past.

The student will use a numerical weather prediction (the Met Office Unified Model) model to investigate the impact of different WAIS configurations on the generation of downslope winds (following Orr et al., 2014). Ice sheet configurations would range from moderate grounding line retreat, to removal of the marine-based areas, through to the full removal of the WAIS. Further, in order to investigate the relationship between localised wind strength and moraine formation, the Elmer model will also be employed to look at the localised wind field (e.g. Zwinger et al., 2015), and the resultant ice flow (using Elmer/Ice). The successful applicant for this project will spend time at the British Antarctic Survey, the Met Office, and the University of Bristol, receiving training in the use of both climate and ice flow models.

See please http://www.exeter.ac.uk/studying/funding/award/?id=2248 for more details on how to apply.

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Type / Role:

PhD

Location(s):

South West England