• Sea, Wind, & Fire (Wednesday 10:30AM-Noon)
    Room A102/104/106
    Chair: Xiaoye Li, Lawrence Berkeley National Laboratory

    • Title: Coastal Ocean Modeling of the U.S. West Coast with Multiblock Grid and Dual-Level Parallelism
    • Authors:
      Phu V. Luong (Engineer Research and Development Center, Major Shared Resource Center)
      Clay P. Breshears (KAI Software, A Division of Intel Americas, Inc.)
      Le N. Ly (Naval Postgraduate School)
    • Abstract:
      In coastal ocean modeling, a one-block rectangular grid for a large domain has large memory requirements and long processing times. With complicated coastlines, the number of grid points used in the calculation is often the same or smaller than the number of unused grid points. These problems have been a major concern for researchers in this field.

      Multiblock grid generation and dual-level parallel techniques are solutions that can overcome these problems. The Multiblock Grid Princeton Ocean Model (MGPOM) uses Message Passing Interface (MPI) to parallelize computations by assigning each grid block to a unique processor. Since not all grid blocks are of the same size, the workload between MPI processes varies. Pthreads is used to improve load balance.

      Performance results from the MGPOM model on a one-block grid and a 29-block grid simulation for the U.S. west coast demonstrate the efficacy of both the MPI-Only and MPI-Pthreads code versions.

    • Title: Terascale spectral element dynamical core for atmospheric general circulation models
    • Authors:
      Richard D. Loft (National Center for Atmospheric Research)
      Stephen J. Thomas (National Center for Atmospheric Research)
      John M. Dennis (National Center for Atmospheric Research)
      Gordon Bell Prize Finalist
    • Abstract:
      Climate modeling is a grand challenge problem where scientific progress is measured not in terms of the largest problem that can be solved but by the highest achievable integration rate. These models have been notably absent in previous Gordon Bell competitions due to their inability to scale to large processor counts. A scalable and efficient spectral element atmospheric model is presented. A new 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. Execution rates are reported for the standard shallow water and Held-Suarez climate benchmarks on IBM SP clusters. The explicit T170 equivalent multi-layer shallow water model sustains 343 Gflops at NERSC, 206 Gflops at NPACI (SDSC) and 127 Gflops at NCAR. An explicit Held-Suarez integration sustains 369 Gflops on 128 16-way IBM nodes at NERSC.

    • Title: High Resolution Weather Modeling for Improved Fire Management
    • Authors:
      Kevin Roe (Maui High Performance Computing Center)
      Duane Stevens(University of Hawaii)
      Carol McCord (Maui High Performance Computing Center)
    • Abstract:
      A critical element to the accurate prediction of fire/weather behaviour is the knowledge of near-surface weather. Weather variables, such as wind, temperature, humidity and precipitation, make direct impacts on the practice of managing prescribed burns and fighting wild fires. State-of-the-art Numerical Weather Prediction (NWP), coupled with the use of high performance computing, now enable significantly improved short-term forecasting of near-surface weather at a 1-3 km grid resolution.

      This proof of concept project integrates two complementary model types to aid federal agencies in real-time management of fire. (1) A highly complex, full-physics mesoscale weather prediction model (MM5) which is applied in order to estimate the weather fields up to 72 hours in advance. (2) A diagnostic fire behavior model (FARSITE) takes the near-surface weather fields and computes the expected spread rate of a fire driven by wind, humidity, terrain, and fuels (i.e. vegetation).