Development and performance of a new version of the OASIS coupler , OASIS 3-MCT _ 3 . 0

OASIS is coupling software developed primarily for use in the climate community. It provides 10 the ability to couple different models with low implementation and performance overhead. OASIS3-MCT is the latest version of OASIS. It includes several improvements compared to OASIS3 including elimination of a separate hub coupler process, parallelization of the coupling communication and run time grid interpolation, and the ability to easily reuse mapping weights files. OASIS3-MCT_3.0 is the latest release and includes the ability to couple between components running sequentially on the same set of tasks 15 as well as to couple within a single component between different grids or decompositions such as physics, dynamics, and I/O. OASIS3-MCT has been tested with different configurations on up to 32,000 processes, with components running on high-resolution grids with up to 1.5 million grid cells, and with over 10,000 two dimensional coupling fields. Several new features will be available in OASIS3-MCT_4.0 and some of those are also described. 20