An atmosphere-ocean forecast system on a hybrid architecture

An operational forecast system is being developed at ENEA, which consists of a high resolution meteorological limited area model coupled with ocean models for the prediction of the state of the Mediterranean Sea and of high water events in the Venice Lagoon. In order to satisfy the operational requirement (3-days forecasts in a few hours) a very effective two level parallelization strategy was adopted: the parallel implementation of the most time-consuming codes and the simultaneous execution of different models. Following this approach, the integrated system has been implemented on the hybrid machine PQE1, which integrates the Meiko CS-2 MIMD architecture and the APE100/Quadrics SIMD architectures by means of HiPPI channels. The first level of parallelism allowed to obtain a highly performing meteorological code QBOLAM, running at more than 2 GFlops sustained on a 128 nodes Quadrics machine. The second level of parallelism allowed to gain more than a factor 2 with respect to the sequential execution of the different processes.