Design and Performance of a Scalable Parallel Community Climate Model

We describe the design of a parallel global atmospheric circulation model, PCCM2. This parallel model is functionally equivalent to the National Center for Atmospheric Research's Community Climate Model, CCM2, but is struc-tured to exploit distributed memory multicomputers. PCCM2 incorporates parallel spectral transform, semi-Lagrangian transport, and load balancing algorithms. We present detailed performance results on the IBM SP2 and Intel Paragon. These results provide insights into the scalability of the individual parallel algorithms and of the parallel model as a whole.