| 研究実績の概要 |
Computer simulations have become established as an important technique for the understanding of ice sheet dynamics. In particular, they are relevant for predicting the evolution of ice sheets in a future changing climate. The goal of this project was to develop an operational ice sheet model that employs the technique of GPU- (graphics processing unit) accelerated computing.
This model, termed "Sainou", is an Elmer/Ice (elmerice.elmerfem.org) derivative that solves the full-Stokes equations (no stresses neglected) of ice dynamics with the finite element method. In the second project year (FY 2016), the focus was on testing Sainou, using an established benchmark problem, namely the ISMIP-HOM experiment A (Pattyn et al., 2008, Cryosphere 2, 95-108). This experiment consists of an inclined slab of ice flowing over a bumpy bed.
The computing time required by Sainou for the assembly of the finite element matrix of the full-Stokes system of partial differential equations was compared to that required by Elmer/Ice. Four different numbers of elements were tested for the ISMIP-HOM experiment A, and the simulations were carried out on a Mac Pro workstation, using only a single CPU. It was found that, for double-precision accuracy with 8000, 87500, 252000 and 391500 brick elements, respectively, Sainou is 7x, 17x, 23x and 25x faster than Elmer/Ice, and for single-precision accuracy it is even 9x, 38x, 45x and 49x faster. It could therefore be demonstrated successfully that GPU-accelerated computing is a useful method for fast and efficient ice sheet modelling.
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