CMIP5 Model Output Metadata Requirements

Past experience with model intercomparison projects, highlighted by the third phase of the Coupled Model Intercomparison Project (CMIP3), has demonstrated the exceptional value gained by archiving multi-model output in a structured and uniform way. The user community now expects to be able to extract data both efficiently and uniformly across all models. The effort to write the data in a uniform structure and format falls on the modeling centers contributing the data. Building on CMIP3, we are now preparing for the fifth phase of CMIP (CMIP5). In CMIP5, a more comprehensive suite of experiments is planned, and a more extensive list of model outputs is requested. Here, we provide the specifications for writing CMIP5 model output. It should be noted that these requirements also extend to the output from intercomparison experiments closely aligned with (or incorporated as part of) CMIP5, including AMIP, CFMIP, C4MIP, PMIP, and TAMIP.