Abstract
We have developed a general-purpose simple coupler (Scup) that can be used for earth system modeling. Scup allows flexible coupling among component models, for example, atmosphere and ocean general circulation models and chemical transport models. Although Scup has provided functions that are required for the efficient development of an earth system model at the Meteorological Research Institute, its fundamental design should also be applicable to other earth system models. Processes of the component models communicate with each other directly by calling the Scup library, which is necessary to efficiently exchange large amounts of grid data among the processes of the component models. Scup supports grid transformation for three-dimensional data and that for two-dimensional data with accurate local and global conservation, necessary features for coupling component models with different coordinates or grids. Simplicity and ease of use are among Scup's strong points. All of the source code is written in Fortran and can be compiled on various platforms with a Fortran 95 compiler and a Message Passing Interface library, so it has good portability.
