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We document the configuration and emergent simulation features from the Geophysical Fluid Dynamics Laboratory (GFDL) OM4.0 ocean/sea ice model. OM4 serves as the ocean/sea ice component for the GFDL climate and Earth system models. It is also used for climate science research and is contributing to the Coupled Model Intercomparison Project version 6 Ocean Model Intercomparison Project. The ocean component of OM4 uses version 6 of the Modular Ocean Model and the sea ice component uses version 2 of the Sea Ice Simulator, which have identical horizontal grid layouts (Arakawa C-grid). We follow the Coordinated Ocean-sea ice Reference Experiments protocol to assess simulation quality across a broad suite of climate-relevant features. We present results from two versions differing by horizontal grid spacing and physical parameterizations: OM4p5 has nominal 0.5° spacing and includes mesoscale eddy parameterizations and OM4p25 has nominal 0.25° spacing with no mesoscale eddy parameterization. Modular Ocean Model version 6 makes use of a vertical Lagrangian-remap algorithm that enables general vertical coordinates. We show that use of a hybrid depth-isopycnal coordinate reduces the middepth ocean warming drift commonly found in pure z* vertical coordinate ocean models. To test the need for the mesoscale eddy parameterization used in OM4p5, we examine the results from a simulation that removes the eddy parameterization. The water mass structure and model drift are physically degraded relative to OM4p5, thus supporting the key role for a mesoscale closure at this resolution. [ABSTRACT FROM AUTHOR]

The World Climate Research Programme (WCRP)'s Working Group on Climate Modelling (WGCM) Infrastructure Panel (WIP) was formed in 2014 in response to the explosive growth in size and complexity of Coupled Model Intercomparison Projects (CMIPs) between CMIP3 (2005-2006) and CMIP5 (2011-2012). This article presents the WIP recommendations for the global data infrastructure needed to support CMIP design, future growth, and evolution. Developed in close coordination with those who build and run the existing infrastructure (the Earth System Grid Federation; ESGF), the recommendations are based on several principles beginning with the need to separate requirements, implementation, and operations. Other important principles include the consideration of the diversity of community needs around data - a data ecosystem - the importance of provenance, the need for automation, and the obligation to measure costs and benefits. This paper concentrates on requirements, recognizing the diversity of communities involved (modelers, analysts, software developers, and downstream users). Such requirements include the need for scientific reproducibility and accountability alongside the need to record and track data usage. One key element is to generate a dataset-centric rather than system-centric focus, with an aim to making the infrastructure less prone to systemic failure. With these overarching principles and requirements, the WIP has produced a set of position papers, which are summarized in the latter pages of this document. They provide specifications for managing and delivering model output, including strategies for replication and versioning, licensing, data quality assurance, citation, long-term archiving, and dataset tracking. They also describe a new and more formal approach for specifying what data, and associated metadata, should be saved, which enables future data volumes to be estimated, particularly for well-defined projects such as CMIP6. The paper concludes with a future facing consideration of the global data infrastructure evolution that follows from the blurring of boundaries between climate and weather, and the changing nature of published scientific results in the digital age. [ABSTRACT FROM AUTHOR]

The World Climate Research Programme (WCRP)'s Working Group on Climate Modeling (WGCM) Infrastructure Panel (WIP) was formed in 2014 in response to the explosive growth in size and complexity of Coupled Model Intercomparison Projects (CMIPs) between CMIP3 (2005-06) and CMIP5 (2011-12). This article presents the WIP recommendations for the global data infrastructure needed to support CMIP design, future growth and evolution. Developed in close coordination with those who build and run the existing infrastructure (the Earth System Grid Federation), the recommendations are based on several principles beginning with the need to separate requirements, implementation, and operations. Other important principles include the consideration of data as a commodity in an ecosystem of users, the importance of provenance, the need for automation, and the obligation to measure costs and benefits. This paper concentrates on requirements, recognising the diversity of communities involved (modelers, analysts, software developers, and downstream users). Such requirements include the need for scientific reproducibility and accountability alongside the need to record and track data usage for the purpose of assigning credit. One key element is to generate a dataset-centric rather than system-centric focus, with an aim to making the infrastructure less prone to systemic failure. With these overarching principles and requirements, the WIP has produced a set of position papers, which are summarized here. They provide specifications for managing and delivering model output, including strategies for replication and versioning, licensing, data quality assurance, citation, long-term archival, and dataset tracking. They also describe a new and more formal approach for specifying what data, and associated metadata, should be saved, which enables future data volumes to be estimated. The paper concludes with a future-facing consideration of the global data infrastructure evolution that follows from the blurring of boundaries between climate and weather, and the changing nature of published scientific results in the digital age. [ABSTRACT FROM AUTHOR]

For effective comparison of Earth system models in large multi-model ensembles one must first have an understanding of the model design, accurate knowledge of the requirements of experiments and insight into how forcing constraints are implemented.Earth system modelling involves many roles, from those involving model construction, to those involving devising, executing, and exploiting numerical experiments. In most cases these roles involve multiple people, and in many cases these people are in different institutions and may only interact via published information (whether journal papers, technical notes, or websites). These multiple people, sources and methodologies lead to scope for misinterpretation of intent and misunderstanding of what was actually done. We present the ES-DOC documentation methodology and information sharing ecosystem which allows the Earth system modelling community to accurately document and share information about both the design of their models and also about how their models are configured to conform to common forcing protocols.We describe how ES-DOC concepts have been applied to the design phase of CMIP6, improving not only the documentation of CMIP6, but also improving the experiments themselves. As a consequence we believe it will be easier for both the MIP designers and participants to be confident that they have requested, understood and/or executed what was required. [ABSTRACT FROM AUTHOR]