The future is Nye: an extension of the perfect plastic approximation to tidewater glaciers

• Published in: Journal of Glaciology
• Main Authors: LIZZ ULTEE, JEREMY BASSIS
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2016
• Subjects: calving; glacial rheology; ice dynamics; ice/ocean interactions; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; glacier; glaciers; Journal of Glaciology; Tidewater; Alaska
• Online Access: https://doi.org/10.1017/jog.2016.108; https://doaj.org/article/eefbb6507af54066b7069f41673e9c59

Accurate modeling of calving glaciers relies on knowledge of many processes (ice flow, surface/submarine melting, calving, mélange interaction) and glacier-specific factors (air temperature, ocean circulation, precipitation rate, glacier geometry) that remain challenging to assess. Iceberg calving, especially, is important to glacier mass loss and difficult to resolve in currently-available models. Given these challenges facing even the most sophisticated models, there is value in simple, computationally-efficient models that can capture first-order effects. In this study we derive a simple model, extending Nye's perfect plastic approximation to include a yield surface at the calving front. With one climate-related input—either an upstream glacier thinning rate or glacier-wide accumulation—this model is able to simulate the advance and retreat of marine-terminating glaciers on annual to decadal scales. Our model requires knowledge of only two glacier-specific factors: glacier bed topography and basal shear strength, both reasonably constrained by laboratory and field observations. We apply the model to a case study of Columbia Glacier, Alaska and show that, despite its simplicity, the model succeeds in reproducing observed centerline profiles and rates of terminus retreat up to 2007.