1] We developed a real-time numerical simulator for the solar wind --space --magnetosphere -ionosphere coupling system, adopting the three-dimensional (3-D) magnetohydrodynamic (MHD) simulation code developed by Tanaka. By using the real-time solar wind data, which is available from the ACE spacecraft every minute, as the upstream boundary conditions for density, temperature, flow speed, and interplanetary magnetic field, our MHD simulation system can numerically reproduce the global response of the magnetosphere and ionosphere at the same time as in the real world. We achieved realtime 3-D simulations of the solar wind --magnetosphere --ionosphere coupling system with a 44 Â 56 Â 60 mesh size by adapting high-performance FORTRAN language with eight CPUs on a supercomputer system located at the National Institute of Information and Communications Technology (NICT). Simulated plasma temperature and density in geostationary orbit were also plotted as an index to predict satellite charging. In addition, we present real-time virtual AE indices obtained from simulation results that directly compare with geomagnetic field activities as well as real-time plasma temperature and density in geostationary orbit. Our real-time MHD simulator now runs routinely on NICT's supercomputer system. We will present a detailed configuration of the real-time simulator system in this paper. Some examples are presented from system output to show how solar wind variations result in geomagnetic disturbances.Citation: Den, M., et al. (2006), Real-time Earth magnetosphere simulator with three-dimensional magnetohydrodynamic code, Space Weather, 4, S06004,
In an electromagnetic particle simulation for magnetic reconnection in an open system, which has a free boundary condition, particles go out and come into the system through the boundary and the number of particles depends on time. Besides, particles are locally attracted due to physical condition. Accordingly, it is hard to realize an adequate load balance with domain decomposition. Furthermore, a vector performance does not become efficient without a large memory size due to a recurrence of array access. In this paper, we parallelise the code with High Performance Fortran. For data layout, all field data are duplicated on each parallel process, but particle data are distributed among them. We invent an algorithm for the open boundary of particles, in which an operation for outgoing and incoming particles is performed in each processor, and the only reduction operation for the number of particles is executed in data transfer. This adequate treatment makes the amount and frequency of data transfer small, and the load balance among processes relevant. Furthermore, a compiler-directive listvec in the gather process dramatically decreases the memory size and improves the vector performance. Vector operation ratio becomes about 99.5% and vector length turns 240 and over. It becomes possible to perform the simulation with 800 million particles in 512 × 128 × 64 meshes. We succeed in opening a path for a large-scale simulation.
SUMMARYWe are developing HPF/SX V2, a High Performance Fortran (HPF) compiler for vector parallel machines. It provides some unique extensions as well as the features of HPF 2.0 and HPF/JA. In particular, this paper describes four of them: (1) the ON directive of HPF 2.0; (2) the REFLECT and LOCAL directives of HPF/JA; (3) vectorization directives; and (4) automatic parallelization. We evaluate these features through some benchmark programs on NEC SX-5. The results show that each of them achieved a 5-8 times speedup in 8-CPU parallel execution and the four features are useful for vector parallel execution. We also evaluate the overall performance of HPF/SX V2 by using over 30 well-known benchmark programs from HPFBench, APR Benchmarks, GENESIS Benchmarks, and NAS Parallel Benchmarks. About half of the programs showed good performance, while the other half suggest weakness of the compiler, especially on its runtimes. It is necessary to improve them to put the compiler to practical use.
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