PMIP 2 Output Format Overview

The climate models comparison projects have to deal with a growing number of files that have to be checked, stored... and redistributed!

The only way to get any of this done in a reasonable amount of time and make sure the data can actually be used during the course of the project (and hopefully later), is to use standards both for the data files and the metadata associated with the files (and usually included in the files).

The PMIP 2 project requires therefore that the participants prepare their data files so that they meet the following constraints (regardless of the way their models produce and store their results).

• The data files have to be in the (now widely used) NetCDF binary file format and conform to the CF (Climate and Forecast) metadata convention.
  
  
• There must be only one output variable per file.
  
  
• For the data that are a function of longitude and latitude, only regular grids (grids representable as a Cartesian product of longitude and latitude axes) are allowed.
  
  
• The file names have to follow the MOTIF/PMIP2 file name convention and be unique.

More precise details about the variables and their associated metadata can be found in the IPCC requirements and the PMIP 2 adaptation pages.

Although it is entirely possible to create output data file that meet ALL the mentioned constraints from scratch, we strongly suggest that you create the files you will submit to the database with the CMOR library. This library has been specically developped to help you meet the requirements of the xMIP Model Intercomparison Projects.