PMIP 2 and the IPCC Requirements


Except for a few differences (listed in the Output requirements adaptation to PMIP 2 page), the PMIP 2 project has the same constraints as IPCC. The tables at the end of this page give an easy access to the IPCC requirements documents, as well as to the NetCDF library and the CF specification (if you want to know more about it).

You will probably have to read the documents mentioned below several times when you prepare your data for submission to the database, but if you are new to this, we suggest you read the documents in the following order:

  1. Requirements for IPCC Standard Output
    This will tell you what structure your NetCDF file should have, what your output variable should look like (data type, axes' order, missing values, ...) and how to define the coordinate variables (data type, names, units, ...). This document is quite detailed and also gives you all the attributes you have to associate with the variables, axes and the file itself, so you don't really need to visit the CF web site.

  2. IPCC Standard Output
    This document tells you what variables have to be submitted to IPCC and at what frequency, as well as the normalized IPCC experiment names. The variables are divided into groups or tables, depending on the type of the variable (Atmosphere or Ocean), the frequency (1: monthly, 2: daily, ...) and the shape or priority (a, b, c, ...).
       e.g. A1c = Monthly-mean (A1c) 3-d (A1c) atmosphere (A1c) data.
    Each variable entry in a table gives you the standard_name of the variable (as specified by the CF convention, when possible), the output variable name (the actual name of the variable in the NetCDF file, that also appears in the file name), the variable's units, and notes (when needed). These information (except for the notes) also appear in the CMOR IPCC configuration tables, that you may also want to have a look at.

    Note: be careful that IPCC and PMIP 2 have some variables in common, but not all! And PMIP 2 do not require the same frequencies as IPCC either. For the common variables, use the same names and units as for IPCC.

  3. CMOR IPCC configuration tables
    These tables give the same information as the IPCC Standard Output document, as well as related metadata information that is required by the CMOR library (coordinate axes information, sign conventions, allowed range for the variables, ...).

Note: The PCMDI and the local version of the files listed below should be the same... but we strongly advise you to always check both versions and work with the latest one!



Requirements for IPCC Standard Output Contributed to the PCMDI Archive [www]

IPCC Standard Output from Coupled Ocean-Atmosphere GCMs [www]
    History of changes [www]  
CMOR IPCC configuration tables [ftp] [http]


  Web Download
UNIDATA NetCDF (network Common Data Form) library

An interface for machine-independant array-oriented data access
[www] [ftp]

A library for manipulating units of physical quantities
[www] [ftp]


NetCDF Climate and Forecast (CF) Metadata Convention [www]  
Overview of CF

Jonathan Gregory
CGAM, Department of Meteorology, University of Reading, UK Met Office Hadley Centre, UK
[pdf] [pdf]
The CF Metadata Standard

Jonathan Gregory, CLIVAR Exchanges No 28, December 2003
[pdf] [pdf]

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