A COMPARISON OF DATA-PARALLEL AND MESSAGE-PASSING VERSIONS OF THE MIAMI ISOPYCNIC COORDINATE OCEAN MODEL (MICOM)

A two-pronged effort to convert a recently developed ocean circulation model written in Fortran-77 for execution on massively parallel computers is described. A data-parallel version was developed for the CM-5 manufactured by Thinking Machines, Inc., while a message-passing version was developed for both the Gray T3D and the Silicon Graphics ONYX workstation. Since the time differentiation scheme in the ocean model is fully explicit and does not require solution of elliptic partial differential equations, adequate machine utilization has been achieved without major changes to the original algorithms. We developed a partitioning strategy for the message passing version that significantly reduces memory requirements and increases model speed. On a per-node basis (a T3D node is one Alpha processor, a CM-5 node is one Spare chip and four vector units), the T3D and CM-5 are found to execute our ''large'' model version consisting of 511 x 511 horizontal mesh points at roughly the same speed.