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.