MESSy

The overview over MESSy's functionalities is taken from https://messy-interface.org, where always the most up-to-date information can be found.

The MESSy software provides

• a modular kit with generalized interfaces for the standardized control and coupling of low-level ESM components (components describe individual processes in the troposphere and middle atmosphere and also feedback with ocean, land and anthropogenic influences),
• the full hierarchy of model systems ranging from idealised box model setups, over simplified climate model configurations, global circulations models including atmospheric chemistry, to fully coupled representations of the Earth system including coupling with an interactive ocean,
• a scalable model development with overall low complexity so that the model remains controllable in a transparent and user friendly way.

The development of MESSy and its submodels is a multi-institutional effort. Scientific and technical exchange between the different groups and institutions is coordinated by the MESSy consortium.

MESSy submodels cover a large variety of applications and can be grouped into infrastructure submodels (framework), diagnostic submodels, physics submodels, and atmospheric chemistry submodels including those describing kinetics, photolysis, emissions, aerosols, and sinks. The process and diagnostic submodels are connected via a standard interface to the MESSy infrastructure. The infrastructure covers several submodels dealing with rather technical details, as memory or object management, or input/output.

The main design concept of MESSy is the strict separation of these process and diagnostic submodels from model HPC software infrastructure like memory management, input/output, flow control and so on. This is referred to as ‘separation of concerns’ and operator splitting is used as the fundamental concept. The model code is organized in four conceptual software layers as a basis for internal modularity. Object-oriented approaches are utilized where possible, taking into account the computational performance.

To summarize, the MESSy approach provides a research tool for a large community serving a wide variety of scientific needs. Yet, the overall complexity remains controllable in a transparent and user-friendly way. Clearly, MESSy is and has proven to be a long-term solution for the modelling community, since it is able to adapt to changes and changing community requirements with its modular structure.