Running the NIM Next-Generation Weather Model on GPUs

We are using GPUs to run a new weather model being developed at NOAA´s Earth System Research Laboratory (ESRL). The parallelization approach is to run the entire model on the GPU and only rely on the CPU for model initialization, I/O, and inter-processor communications. We have written a compiler to convert Fortran into CUDA, and used it to parallelize the dynamics portion of the model. Dynamics, the most computationally intensive part of the model, is currently running 34 times faster on a single GPU than the CPU. We also describe our approach and progress to date in running NIM on multiple GPUs.