A shallow approximation for ice streams sliding over strong beds

• Published in: Journal of Glaciology
• Main Authors: Katarzyna L. P. Warburton, Duncan R. Hewitt, Colin R. Meyer, Jerome A. Neufeld
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press
• Subjects: glacier flow; glacial rheology; ice dynamics; ice streams; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Ice Sheet; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2023.47; https://doaj.org/article/7e6b45e837644611a3fac8d9fac913f2

Ice streams are regions of rapid ice sheet flow characterised by a high degree of sliding over a deforming bed. The shallow shelf approximation (SSA) provides a convenient way to obtain closed-form approximations of the velocity and flux in a rapidly sliding ice stream when the basal drag is much less than the driving stress. However, the validity of the SSA approximation breaks down when the magnitude of the basal drag increases. Here we find a more accurate expression for the velocity and flux in this transitional regime before vertical deformation fully dominates, in agreement with numerical results. The closed-form expressions we derive can be incorporated into wider modelling efforts to yield a better characterisation of ice stream dynamics, and inform the use of the SSA in large-scale simulations.