CPOM Staff based at Bristol
Anne Le Brocq
| email: a.lebrocq |
Tel: 0117.928.9954 |
| Fax: 0117.928.7878 |
Anne was awarded a M.Sc in Geographical Information Science (GIS) from the University of Edinburgh and obtained a B.Sc in Geography from Bristol University.
Her research project is entitled: "Validating models of the West Antarctic Ice Sheet".
Project Outline:
The West Antarctic Ice Sheet (WAIS) has been the subject of intensive research over the past decade. Research has focussed on the area for two reasons. First, the marine nature of the ice sheet may make it prone to rapid retreat in the face of rising sea levels. Second, there is a wealth of evidence that implies the changes are occurring in the area at rates far greater than previously thought possible. This latter work focuses on the dynamics of the ice streams draining the ice sheet in two main areas: the Bellingshausen Coast and the Siple Coast.
An analysis of satellite-altimetry data identifies that the combined Thwaites and Pine Island drainage basin (draining to the Bellingshausen Sea) is experiencing ice-surface lowering at a rate in excess of that explicable solely in terms of snowfall variability. A dynamic forcing is therefore likely. More detailed studies of Thwaites and Pine Island Glaciers (PIG), as well as Smith Glacier, indicate that the grounding line of PIG retreated at the rate of 1.2km yr-1 during the 1990's and that this retreat was accompanied by ice-surface lowering (at a rate of ~ 1m yr-1) up to 150km inland of the grounding line. The latter effect appears to be related to a general acceleration in the vicinity of PIG and a similar draw down is observed on Thwaites (~0.5 m yr-1) and Smith Glaciers (~3.2 m yr-1).
The study of the Siple Coast ice streams has a far longer history and has been accomplished using a mixture of satellite, airborne, field and modelling techniques. They have clearly had a complex evolution and there are instances of ice stream shutdown, for instance Ice Stream C at roughly 140 years ago and the Siple Ice Stream roughly 450 years ago. There is also evidence for the widening, as well as head-ward and lateral migration of the ice streams. A recently published estimate of the area's overall mass balance is strongly positive with average ice thickening equal to approximately 25% of the annual accumulation rate. The majority of this signal is associated with the stagnation of Ice Stream C.
The
majority of this work is based around field (drilling, seismic survey and
radio-echo sounding, RES), airborne (RES) and remote-sensing (inferometry
and altimetry) techniques. A relatively small number of modelling studies
have been performed. To date no attempt has been made to rigorously validate
a model of the WAIS. This aim of this project is to attempt this validation
for an existing WAIS model using a variety of information drawn from the different
sources outlined above.