|From||Daniel Goldberg <email@example.com>|
|Date||Fri, 24 Nov 2017 10:11:24 -0600|
At the margin of the Antarctic Ice Sheet the ice goes afloat as large ice shelves. In some cases massive inverted “channels” have been observed beneath the ice shelves, thought to be eroded by underlying warm oceans. Depending on their details of formation, these channels take on different patterns, and can lead to crevassing, thereby weakening the ice shelves. This is important because ice shelves hold back the flow of the ice sheet inland, and ice loss from ice sheets is causing global sea levels to rise. A number of theoretical and numerical studies have been carried out to study the formation and implications of basal channels [e.g., Vaughan et al, 2012; Sergienko, 2013]; however, all of these studies neglect physical processes which may fundamentally affect the nature of the channels and how they affect ice-sheet stability. Specifically, neither channel interactions with ocean circulation or channel-induced crevassing have been fully investigated.
Aims and Methodology: The project will address three research questions:
RQ1: What are the glaciological and oceanographic conditions under which sub-ice shelf channels form, and what controls their morphology?
RQ2: What effect does channel formation have on ice-shelf crevassing?
RQ3: How does channel formation feed back on large scale ice-shelf stability?
These questions will be answered using numerical modelling, constrained by geophysical and remotely-sensed data where possible. RQ1 will use a new model of coupled ice-ocean interaction that can capture the fast time scales and small spatial scales that will be investigated here [Jordan et al, 2017]. This model has already been observed to reproduce channel-like structures, though more thorough investigation is needed. Through a range of comprehensive numerical experiments, the conditions for channel formation will be determined. RQ2 will be addressed by studying the effects of channel-induced flexure on ice-shelf stresses and how they may lead to crevassing and damage. The work will involve integrating equations for viscous flexure [e.g. MacAyeal et al, 2015] into the ice shelf component of the coupled model. RQ3 will be addressed by investigating the interactions between channels and large-scale ice shelf and ice sheet flow. It has already been observed that incised channels play a role in weakening the ice shelves’ resistance to flow through focused thinning, but the impact of channel-induced crevassing is unknown. The student will develop a parameterization for the effect of channel-induced crevassing on ice shelf damage and weakening, which could potentially lead to ice shelf instability and collapse [Borstad et al, 2013].
Requirements: We seek a motivated student with a suitable undergraduate or Masters degree in physics, mathematics or a relevant science subject. The student should have some familiarity with scientific programming.
This project is funded through the NERC Edinburgh E3 Doctoral Training Program. See http://e3dtp.geos.ed.ac.uk/ for details on eligibility and application. Informal inquiries should be directed to Daniel Goldberg (firstname.lastname@example.org).
References: Borstad et al (2013), Cryosphere, 7:1931--1947. Gourmelen et al (2017), Geophys. Res. Lett, 44, 9796–9804. Jordan et al (2017), J. Geophy. Res-Oceans, doi:10.1002/2017JC013251. LeBrocq et al (2014), Nat. Geosc. 6, 945-948. MacAyeal et al (2015). Journal of Glaciology, 61(228), 635-645. Sergienko, O. V. (2013), J. Geophys. Res. Earth Surf., 118,1342–1355. Vaughan et al (2012), J. Geophys. Res. Earth Surf., 117, F03012.
The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.
Go to: Periods · List Information · Index by: Date (or Reverse Date), Thread, Subject or Author.