Radio-echo sounding of Pine Island Glacier, West Antarctica : understanding the past from observations, analysis and modelling of internal layering

Pine Island Glacier is one of the fastest and most dynamic glaciers in West Antarctica. The stability of the glacier may thus have profound impact on the overall stability of the West Antarctic Ice Sheet and its contribution to global sea-level rise. This thesis addresses questions concerning the past dynamics of the glacier using observations of the internal layers in the ice imaged by radio-echo sounding. Results from an extensive internal layer classification showed that no major spatial changes have taken place in the glacier although the analyses did identify signs indicating a past change of flow pattern in several localised areas in the northern part of the catchment basin. Results also indicated that different parts of Pine Island Glacier are likely to respond in different ways to external forcing. The analyses of the radar data were facilitated by the development of new methods for layer classification and tracing. The second part of this thesis focussed on modelling the internal layers using two- and three-dimensional numerical ice flow models. Comparisons between the observed layers and results from the three-dimensional model indicated that a likely change in accumulation rate and pattern had taken place during the past 7 kyr - 17.5 kyr. The model also indicated a time scale for the changes in flow pattern of approximately 6 - 10 kyr. Results from the two-dimensional model further highlighted areas likely to have undergone changes in past ice flow pattern. The results from this study can feed into current efforts to understand the past dynamics of WAIS in order to establish its response to future climate change