Parallel I/O for 3-D Global FDTD Earth–Ionosphere Waveguide Models at Resolutions on the Order of ~1 km and Higher Using HDF5

3-D finite-difference time-domain (FDTD) models of the global Earth-ionosphere waveguide have reached grid resolutions on the order of 1 × 1 × 1 km and higher. At these high resolutions, efficient parallel input-output (I/O) schemes are required to keep the simulation run times reasonable. However, generating optimal parallel I/O schemes is challenging due to the spherical-coordinate global mesh that includes merging of cells in the east-west direction as either pole is approached. Hierarchical Data Format 5 (HDF5) is applied and optimized for a global latitude-longitude FDTD model. The performance of the parallel HDF5 approach is compared with a message passing interfacebased approach and a brute-force approach. The methodology presented here may be simplified to Cartesian-based grids in a straightforward manner.