About the WCRP CMIP3
Multi-Model Dataset Archive at PCMDI
In response to a proposed activity of the World Climate
Research Programme's (WCRP's)
on Coupled Modelling (WGCM), PCMDI volunteered to collect model output
contributed by leading modeling centers around the world. Climate model output from
simulations of the past, present and future climate was collected by PCMDI
mostly during the years 2005 and 2006, and this archived data constitutes phase 3 of the
Intercomparison Project (CMIP3). In part, the WGCM organized this
activity to enable those outside the major modeling centers to perform research
of relevance to climate scientists preparing the Fourth Asssessment Report (AR4)
of the Intergovernmental Panel on Climate Change (IPCC).
The IPCC was established by the World Meteorological Organization and the United Nations Environmental Program to assess scientific information on climate change. The IPCC
publishes reports that summarize the state of the science.
This unprecedented collection of recent model output is officially known as
the "WCRP CMIP3 multi-model dataset." It is meant to serve IPCC's
Working Group 1, which focuses on the physical climate system -- atmosphere, land surface, ocean and sea ice -- and the choice of variables archived at the PCMDI reflects this focus.
A more comprehensive set of output for a given model may be available from the
modeling center that produced it.
With the consent of participating climate modelling groups, the WGCM has declared the CMIP3
multi-model dataset open and free for non-commercial purposes. After
registering and agreeing
anyone can now obtain model output via the ESG data portal, ftp, or the
As of January 2007, over 35 terabytes of data were in the archive and over
337 terabytes of data had been downloaded among the more than 1200 registered users.
Over 250 journal articles, based at least in part on the dataset, have been published or have been accepted for peer-reviewed publication.
Latest statistics can be found at: 1) usage, 2)
download rate, 3)
subprojects, and 4)
Information for analysts
Proper citation and acknowledgement
How to access CMIP3
archive and getting started
at a glance
Check errata page frequently
definitions of variables
Official model names
(including simulation forcing information)
Which control simulation (and time period) should each perturbation run be
Information for modeling groups contributing
model output to the CMIP3 archive:
- Please fill out a
questionnaire, indicating your intention to
contribute model output to the IPCC archive.
- Follow the established procedure for preparing
and transferring model output to the IPCC archive,
as summarized in:
Additional important requests and information
Overview presentations concerning the WCRP CMIP3 multi-model dataset archived at
To IPCC WG1 AR4
First Lead Authors Meeting (Trieste, Italy,
26-29 September 2004)
To Workshop on
Analyses of Climate Model Simulations for the IPCC
AR4 (Honolulu, Hawaii, 1-4 March 2005)