Getting Started on the Data Portal:

How to Find and Download IPCC Model Output Through the Data Portal

Tom Phillips, PCMDI

Data Searching
To get a broad overview of IPCC data status, you first may want to consult the Data Availability Summary for a pictorial depiction of the currently available data (time-independent fields as well as time-dependent data at 3-hourly, daily-mean, or monthly-mean sampling frequencies) for various control and climate-change runs from different IPCC models. 

Then consult the Tables of IPCC Standard Output for details (e.g. the acronyms and long names) on the climate variables that are potentially available from each model simulation.  Similar, but less precise, information is given on the IPCC Model Output page. 

Next, consult the Search Instructions

You have the option of making either a basic search or an advanced search.  The former is useful, for example, to determine all the available model simulations of the of the 20th Century climate scenario (supply the acronym 20c3m as the search string).  The basic search also will list different members (run1, run2, etc.) of an ensemble (simulations with the same forcings, but with different initial conditions) of such climate scenarios  for each model, if relevant. (At first, you may only wish to analyze, say, run1 of a model ensemble, but considering more than one ensemble member allows the "robustness" of one's analysis conclusions to be critically examined.)  The advanced search is more relevant if you wish to locate all data sets for a particular climate scenario (e.g. 20c3m) and frequency (e.g. monthly means).  A variant of the advanced search is to find all the files for a particular  climate variable (e.g. total precipitation flux pr) for a particular frequency across specified model simulations or climate scenarios.

Browsing and Downloading Data Using the PCMDI Portal
Consult the Browsing and Downloading Data page for detailed instructions.  Also note that known problems with the IPCC model data are listed on a frequently updated Errata page.

Anyone can browse (i.e. search, as described above) the IPCC archive, but to actually download data you must login with the password you designated when registering.  Then, when the results of your data search are displayed, you can specify which climate variable time series to actually download by checking the appropriate checkbox(es) and submitting a download request.   After your file requests have been staged by the data portal for download (usually within the same day of your request), you will be notified by e-mail.  Clicking the links in this message then will effect the necessary data transfer (via ftp) to your local computer platform.  You then can organize these files according to your own local directory preferences.

Downloading Data Via FTP
Once you are more familiar with the climate scenarios/frequencies/variables/models that are of  most interest, you have the option of directly ftp'ing the desired data, rather than operating through the data portal interface.  This has the advantage of allowing many simultaneous data requests to be effected via a single ftp 'mget' command.  If you want to try this option, see the page on Downloading Data Via FTP for details.