Porting a 3D-model for the transport of reactive air pollutants to the parallel machine T3D

Air pollution forecasting puts a high demand on the memory and the floating point performance of modern computers. For this kind of problems massively parallel computers are very promising, although the software tools and the I/O facilities on those machines are still under-developed. This report describes the work involved to port a 3D model, which was optimized for the parallel vector computer Cray C90, to a parallel distributed memory computer, namely the Cray T3D. After some introductory remarks about the model and the communication therein, examples are given to describe the performance of the T3D-machine on simple problems. Thereafter performance measurements are shown with kernels of the model using shared and explicit programming.