Abstract
Abstract. Ice sheets lose the majority of their mass through outlet glaciers or ice streams, corridors of fast ice moving multiple orders of magnitude more rapidly than the surrounding ice. The future stability of these corridors of fast-moving ice depends sensitively on the behaviour of their boundaries, namely shear margins, grounding zones and the basal sliding interface, where the stress field is complex and fundamentally three-dimensional. These boundaries are prone to thermomechanical localisation, which can be captured numerically only with high temporal and spatial resolution. Thus, better understanding the coupled physical processes that govern the response of these boundaries to climate change necessitates a non-linear, full Stokes model that affords high resolution and scales well in three dimensions. This paper's goal is to contribute to the growing toolbox for modelling thermomechanical deformation in ice by leveraging graphical processing unit (GPU) accelerators' parallel scalability. We propose FastICE, a numerical model that relies on pseudo-transient iterations to solve the implicit thermomechanical coupling between ice motion and temperature involving shear heating and a temperature-dependent ice viscosity. FastICE is based on the finite-difference discretisation, and we implement the pseudo-time integration in a matrix-free way. We benchmark the mechanical Stokes solver against the finite-element code Elmer/Ice and report good agreement among the results. We showcase a parallel version of FastICE to run on GPU-accelerated distributed memory machines, reaching a parallel efficiency of 99 %. We show that our model is particularly useful for improving our process-based understanding of flow localisation in the complex transition zones bounding rapidly moving ice.
Highlights
The fourth IPCC report (Solomon et al, 2007) concludes that existing ice-sheet flow models do not accurately describe polar ice-sheet discharge (e.g. Gagliardini et al, 2013; Pattyn et al, 2008) owing to their inability to simultaneously model slow and fast ice motion (Gagliardini et al, 2013; Bueler and Brown, 2009)
We compare our numerical solutions obtained with the GPUbased PT method using a CUDA C implementation (FastICE) to the reference Elmer/Ice model
We report MTPeff values obtained with the FastICE algorithm for both the vectorised MATLAB (CPU) and the CUDA C (GPU) implementations in double-precision arithmetic (Fig. 17a)
Summary
The fourth IPCC report (Solomon et al, 2007) concludes that existing ice-sheet flow models do not accurately describe polar ice-sheet discharge (e.g. Gagliardini et al, 2013; Pattyn et al, 2008) owing to their inability to simultaneously model slow and fast ice motion (Gagliardini et al, 2013; Bueler and Brown, 2009). Gagliardini et al, 2013; Pattyn et al, 2008) owing to their inability to simultaneously model slow and fast ice motion (Gagliardini et al, 2013; Bueler and Brown, 2009). Shallow ice models are computationally more tractable and describe the motion of large homogeneous portions of ice as a function of the basal friction. Räss et al.: Modelling thermomechanical ice grounding zones and the basal interface These boundaries dictate the stability of the current main drainage routes from Antarctica and Greenland, and predicting their future evolution is critical for understanding polar ice-sheet discharge
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
