CPOM Staff based at UCL
Sophie Nowicki
| email: smn |
tel: 0207.679.4406 |
| fax: 0207.679.7883 |
Sophie was awarded a M.Sc in Remote Sensing and Image Processing with distinction from the University of Edinburgh in 2002 and obtained a B.Sc in Geophysics from the same institution in 2001.
Her Ph.D research project is entitled: "Stability of an ice sheet/ice shelf Junction"
This project is concerned with matter that has lain at the heart of Antarctic glaciology for 30 years. In a 1974 theoretical paper, Weertman suggested that a marine ice sheet (i.e. an ice sheet that terminates by floatation) whose bed gets deeper into the interior, is unstable and that were, for some reason, the ice sheet to start to thin, the thinning would continue until the sheet ceased to exist. This theoretical argument has motivated a great deal of Antarctic glaciological research in the past three decades, because the configuration of the West Antarctic ice sheet (WAIS), which contains a water volume equivalent of 5 metres of sea level, has such a bed configuration. To large extent, however, this research has been inconclusive, not the least because it has proved very difficult to even determine if in fact the WAIS is thinning. Recently, however, satellite observations have shown that thinning extending well into the interior is occurring in the Pine Island and Thwaites Glacier Basins of the West Antarctic ice sheet. These observations give the now old contention that a marine ice sheet may be unstable a new importance: these two glaciers account of 16% of the mass flux from the WAIS.
In fact, a close examination shows that the result of Weetman's theory rests on an assumption concerning the force balance in the region of the grounding line (the locus of points of flotation). This assumption is plausible, but not proven, because to do so requires a solution of the full Stoke's problem in the vicinity of the grounding line, a problem which has proven remarkably resistant to analytic methods. On the other hand, a numerical solution requires a fluid dynamical code of high quality (because the solution has singular aspects) and one that can deal with free surface and buoyancy forces. Such a code ("Basil') has been developed to deal with the apparently very different problem of lithospheric and mantle flow, but it turns out that the mathematics of the two problems is identical. This project is to apply the Basil code to problems of glaciology, and in particular to study the junction problem of the marine ice sheet. Initially, the project will examine very idealised flows whose solution may be checked analytically. As it progresses, however, a wide range of more realistic glacial geometries, sliding laws, etc. may be investigated. The investigations will provide new insight into the behaviour of marine ice sheets.