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Department of Geography

Departmental Research Projects

Determination of a New Global GPS-Derived Surface Velocity Field and its Application to the Problem of 20th Century Sea-Level Rise, The

A research project of the Department of Geography.

Background

This is a large NERC-funded multi-institution project, led by Matt King (Newcastle). The project is reprocessing existing GPS datasets with improved algorithms with a specific focus on improving horizontal and vertical velocity fields for Antarctica.

The Durham-led part of the project aims to improve our understanding of Antarctic postglacial rebound, which arises as a result of both large-scale ice mass variations between the Last Glacial Maximum and the mid-to-late Holocene, and present-day mass changes on a decadal-to-centennial time scale. By improving our knowledge of past changes, the ongoing viscous response to these changes will be able to be removed from present-day observations, allowing us to place tighter constraints on the present-day mass changes that are taking place.

Previous predictions of glacial isostatic adjustment (GIA) across Antarctica have been made using ice sheet histories that were constrained by near- and far-field sea-level data, and geological data, but did not obey ice sheet physics. In this project GIA- and ice sheet modelling will be combined iteratively in order to improve our estimate of ice mass changes across Antarctica over the last 20 kyr. Geological constraints relating to the temporal evolution of ice extent and thickness are used to constrain the development of the ice sheet, which is determined using the dynamic ice sheet model ‘Glimmer’. Once a feasible ice sheet history has been determined, this will be used as an input into the GIA model, from which predictions of global sea-level change over time and present-day deformation rates may be calculated. These predictions will be compared to relative sea-level and the reprocessed GPS data, and misfits will be used to guide improvements to the ice sheet model.

The importance is that our improved GIA modelling will allow satellite gravity measurements to be corrected more accurately for the memory of the ice sheet loading from the last ice age, and so improve measurements of contemporary ice loss.

Published Results

Journal Article

  • Whitehouse, P.L., Bentley, M.J. & Le Brocq, A.M. A deglacial model for Antarctica: geological constraints and glaciological modelling as a basis for a new model of Antarctic glacial isostatic adjustment. Quaternary Science Reviews. 2012;32:1-24.
  • Whitehouse, P.L., Bentley, M.J., Milne, G.A., King, M.A. & Thomas, I.D. A new glacial isostatic adjustment model for Antarctica: calibrated and tested using observations of relative sea-level change and present-day uplift rates. Geophysical Journal International. 2012;190:1464-1482.
  • King, M.A., Keshin, M., Whitehouse, P.L., Thomas, I.D., Milne, G.A. & Riva, R.E.M. Regional biases in absolute sea-level estimates from tide gauge data due to residual unmodeled vertical land movement. Geophysical Research Letters. 2012;39.
  • Nield, G.A., Whitehouse, P.L., King, M.A., Clarke, P.J. & Bentley, M.J. Increased ice loading in the Antarctic Peninsula since the 1850s and its effect on glacial isostatic adjustment. Geophysical Research Letters. 2012.
  • Thomas, I., King, M.A., Bentley, M.J., Whitehouse, P.L., Penna, N.T., Williams, S.D.P., Riva, R.E.M., Lavallee, D.A., Clarke P.J., King, E.C., Hindmarsh, R.C.A. & Koivula, H Widespread low rates of Antarctic glacial isostatic adjustment revealed by GPS observations. Geophysical Research Letters. 2011;38.

Newspaper/Magazine Article

  • King, M.A. & Whitehouse, P. On the Up. Planet Earth. 2012;14-15.

Staff

From the Department of Geography