The CISM code coupling strategy

The success of the Center for Integrated Space Weather Modeling (CISM) depends on the production of an everimproving series of comprehensive scientific models describing the Solar Terrestrial environment from the solar surface to the upper atmosphere of earth. We describe here our strategy for coupling the codes we have selected as the basis for these models, which include core global codes which address the corona, heliosphere, the earth’s magnetosphere, and ionosphere, and codes which model important local processes such as magnetic reconnection. Coupling these codes requires four separate functions: efficient transmission of information among codes, interpolation of grid quantities, translation of physical variables between codes with differing physical models, and control mechanisms to synchronize the interaction of codes. The characteristics of these codes dictate an approach involving loosely coupled groups of independently running programs. We have selected two existing software packages, InterComm and Overture, to provide the basis of our coupling framework. By combining the strengths of these packages, we obtain the benefits of simplified coding of translation routines and inter-grid communication between distinct codes with minimal code modification. The NASA Living With a Star program shares both the scientific goals and code coupling challenges of CISM, and is equally involved in the coupling strategy and development we present. r 2004 Elsevier Ltd. All rights reserved.