1/25 deg Atlantic Ocean Simulation Using HYCOM
Abstract
Traditional ocean models use a single coordinate type to represent the vertical, but no single approach is optimal for the global ocean. Isopycnal (density tracking) layers are best in the deep stratified ocean, z-levels (constant fixed depths) provide high vertical resolution in the mixed layer, and ?-levels (terrain-following) are often the best choice in coastal regions. The HYbrid Coordinate Ocean Model (HYCOM) combines all three approaches by dynamically choosing the optimal distribution at every time step via the layered continuity equation. This has lead to HYCOM being chosen for the next generation of ocean prediction systems both by NAVOCEANO and by NOAA. HYCOM's basic parallelization strategy is 2-D domain decomposition, i.e., the region is divided up into smaller sub-domains, or tiles, and each processor "owns" one tile. Tiles that are entirely over land are discarded. A halo is added around each tile to allow communication operations (e.g., updating the halo) to be completely separated from computational kernels, greatly increasing the maintainability and expendability of the code base. Rather than the conventional 1 or 2 element wide halo, HYCOM has a 6 element wide halo is "consumed" over several operations to reduce halo communication overhead. The communication mechanism implementing domain decomposition can be either MPI or Cray's SHMEM library.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA470557
Entities
People
- Alan J. Wallcraft
- Harley E. Hurlburt ;tamara L. Townsend ;eric P. Chassignet
Organizations
- United States Naval Research Laboratory