Connecting Codes to ICON via the Community Interface (ComIn) - The Modular Earth Submodel System as a first complex ComIn plugin

Abstract

The Modular Earth Submodel System (MESSy) is a software and a framework for the assembly of Earth System Models (ESMs). The MESSy software provides a modular kit with generalized interfaces for the standardized control and coupling of low-level ESM components. MESSy is applied successfully in several configurations coupled to several numerical weather and climate models, also connected to the ICOsahedral Non-hydrostatic model system (ICON) as base model. Because of the lack of an generalized interface, the connection of MESSy with the numerical models introduces additional hard-coded calls to MESSy subroutines in the base model code and several dependencies between the two codes. In a first natESM sprint, we used the novel Community Interface (ComIn) to break up direct dependencies of MESSy on the base model code and substitute the hard coded entry points in ICON with the functionality provided by ComIn. During the development of MESSy as ComIn compatible plugin, we explored restrictions of the approach and shortcomings of the underlying ComIn implementation. Giving direct feedback to the ComIn development process, improvements could be directly implemented in the interface and are available in the first ComIn release. Lessons learned from connecting the rather complex MESSy via ComIn also provide a blueprint for future ComIn plugin developments. This presentation will show the benefits of a generalized interface and a first application of ComIn on a "real-world" example.