Browsing and Downloading Data

Terminology

• A dataset is a collection of related files. In the IPCC database a dataset consists of the files generated by one run of an AOGCM, for a particular temporal frequency (monthly, daily, etc.).
• An ensemble is a collection of simulations run by one model, for one experiment. For example: the CCSM 'Climate of the 20th Century' ensemble.
• An experiment is a scenario, such as 'Climate of the 20th Century'.
• A file is a physical data file.IPCC model output data files typically contain exactly one data variable.
• A project is an activity that generates a set of ensembles. There is only one project in the catalog: the IPCC 4th Assessment project.
• Run: same as simulation.
• A simulation is a single run of a GCM. Runs are identified numerically, starting with '1'.

Browsing

The catalogs are organized hierarchically: Project : Ensemble : Simulation : Dataset : File.

To begin, select the 'IPCC' project link in the Browse Dataset Catalogs on the home page. You will see a list of the ensembles in the IPCC catalog. An ensemble is identified by model name and experiment. Select an experiment link to see all the runs (simulations) that comprise the ensemble. Selecting a run displays the datasets in the run, separated out by temporal frequency (monthly, daily, etc.). Finally, select a dataset to view the list of files in the dataset.

Note that at each level of the browse hierarchy, there are two additional links for metadata and documentation. The metadata link shows the type of object being viewed (ensemble, simulation, ...) and the cataloged metadata. The documentation link points to additional model and simulation data.

Downloading data.

Logging in

Before downloading data you must be a registered user and be logged in. To login without losing the position in the dataset hierarchy:

• Select Login from the menu, and enter your username and password.
• Click the Back button to return to the file or dataset listing.
• Click Reload. The status should change to "Logged in".

Downloading

Selecting a dataset link shows a list of files in the dataset. To download one or more files:

1. For each file to be retrieved, select the checkbox in the Download column.
2. Select the download link in the Download Files section. You will see a list of the files selected.
3. If the list is correct, click Transfer. At this point the portal will transfer the selected files to its local cache, and notify you by email when they are available for download.
4. When you receive notification by email, data can be downloaded by selecting the links in the email message.