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Stephen J Thomas, Richard D Loft, and John M Dennis (2001)
Scalable Spectral Element Climate Dynamical Core
In: Proceedings of the LACSI Symposium, Los Alamos, NM, Los Alamos Computer Institute.
A scalable spectral element atmospheric model is presented that achieves a high percentage of peak on microprocessors. A semi-implicit time stepping scheme accelerates the integration rate relative to an explicit model by a factor of two, achieving 130 years per day at T63L30 equivalent resolution. Simulation results are reported for the standard shallow water and Held-Suarez climate benchmarks. The explicit multi-layer shallow water model sustains 360 Gflops at NERSC, 206 Gflops at NPACI (SDSC) and 127 Gflops at NCAR on IBM SP clusters. An explicit Held- Suarez run sustains over 300 Gflops on the 134 16-way IBM nodes at NERSC. The semi-implicit scheme is hampered by global reductions in the conjugate gradient (CG) algorithm, which scale at a rate higher than O(log P) on IBM SP interconnects. We explore several techniques for improving the scalability of the solver.
