Beyond observations: recovery of unknown parameters in ice flows using optimisation techniques and other tools ...

• Main Author: McGeorge, Elizabeth Kos
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Canterbury 2022
• Subjects: Ice Sheet
• Online Access: https://dx.doi.org/10.26021/14236; https://ir.canterbury.ac.nz/handle/10092/105141

Basal slipping at the ice-bed interface is a key parameter in ice sheet modelling because it can have a large impact on the ice thickness. Unfortunately, its effect on surface observations can be hard to distinguish from that of bed undulations. Therefore, inferring the ice thickness from surface measurements is an interesting, useful, and non-trivial inverse problem. This thesis develops methods for simultaneously recovering the ice thickness and the basal slip, using only surface elevation and velocity measurements. The shallow ice approximation, a time-dependent non-linear partial differential equation for ice thickness evolution, is chosen to model ice flow. Using this model, synthetic surface data is produced for given bedrock and basal slip profiles. To invert the synthesised data, a restriction to unidirectional ice-flow is initially explored. First, a semi-analytical approach is developed and studied. Following its success, an optimisation based approach is implemented. This method requires less data ...