An OASIS 4 climate modelling

Earth system modelling significantly assists climate research. A large number of computational models and platforms that simulate the Earth's systems are used in Europe for climate modelling. In such a diverse and distributed research environment the development of a comprehensive hardware and software infrastructure, is a prerequisite for the continuous improvement in basic understanding of natural processes.

Digital Economy

The PRISM (Programme for integrated earth system modelling) project aimed at providing the European Earth System Modelling community with a common software infrastructure. PRISM software is intended to facilitate broader exchange, dissemination and shared analysis of model results. This means a flexible model structure with interchangeable model components (atmosphere, atmospheric chemistry, land-surface, ocean, sea-ice, ocean bio-geochemistry, or regional models) exchanging information through standard interfaces. In order to achieve these goals, standards have been defined for all aspects of the software, fulfilling the requirement of low maintenance costs, high flexibility and portability. In this framework, an OASIS4 (Ocean Atmosphere Sea Ice Soil) coupler was developed, software that allows synchronized exchanges of coupling information between numerical models representing different components. This software package allows the coupling (data exchange) between any two or more climate component models and the I/O of each individual climate component. OASIS4 consists of a central parallel executable, which initially extracts the configuration information defined by the user in XML files and organizes the process management of the coupled simulation. At run time the central parallel executable performs the re-gridding of the coupling fields. Each ESM application may host only one or more climate component models (e.g. model of the ocean, sea-ice, atmosphere, etc.). To interact with the other component models at run-time the component models need to be interfaced with the PRISM System Model Interface Library, PSMILe. The OASIS PSMILe ensures a fully parallel communication including a parallel neighbourhoods search based on a multi-grid algorithm, to meet the needs of the coupling fields between their source and target grids. The functionality and scalability of OASIS4 application has been demonstrated with different "toy" models, which contain no dynamics but reproduce otherwise realistic conditions. Added to these, portability is an essential characteristic of OASIS4 since it allows the models to run on different platforms. These key design concepts are promising for the success of OASIS4 in meeting the current demands of the climate modelling community.