FAQ Data and Access

When will the CORDEX-CMIP6 data be available and for which domains?

You can find information about planned downscalings, including responsible institutes and contact persons, for CORDEX-CMIP6 here: https://github.com/WCRP-CORDEX/simulation-status

How do I access data from CORDEX?
You can find information on how to access the data following the links on the website under Data access. If you can´t find what you are looking for you can contact the Point of Contact listed for your domain at https://cordex.org under Domains.

How do I download data from ESGF?
Detailed instructions on how to download CORDEX data from ESGF are available on the CORDEX website under ESGF. More user tutorials for ESGF can be found here: https://esgf.github.io/esgf-user-support/index.html.

If I have problems to download files from ESGF ?
If there are any ESGF-related problems (cannot download files etc.) and you need technical support please have a look at the User Tutorials and ESGF FAQ first https://esgf.github.io/esgf-user-support/index.html. If you cannot find what you are looking for please contact the ESGF user support: esgf-user@lists.llnl.gov

How do I access data for a specific country/region?
Look for your region, in CORDEX called a domain (https://www.cordex.org/domains/). For example, the CORDEX-Africa domain has acronym “AFR-44” and covers the entire African continent. See Table 1 in the CORDEX Archive Design (http://is-enes-data.github.io/cordex_archive_specifications.pdf) for a list with acronyms for all CORDEX domains. Suffix “i” in the CORDEX domain acronyms (e.g. AFR-44i) means a regular grid (see Table 2 in the CORDEX Archive Design).

According to the CORDEX Archive Design only monthly and seasonal means are supposed to be remapped to the CORDEX regular grids. Daily and sub-daily output is available on the RCM native grids. At the moment there is no service at ESGF allowing cropping a sub-region from the CORDEX domains

Some data portals can provide such functionality, see for instance Climate4Impact (https://climate4impact.eu/). There are a number of RCM/GCM combinations for all CORDEX domains, more information on these combinations can be found at the first page on the website https://cordex.org. Note that this matrix is sparse, not all RCMs have downscaled all GCMs and some simulations might be missing.

Is CORDEX output data open source? Can I use this data for my academic research without any copyright issue?
The CORDEX data can be used for non-commercial research purposes (see CORDEX Terms of Use). Acknowledgement should be given at the end of the publication/presentation where the CORDEX data is utilized.

Is CORDEX output data freely accessible?
No charge applies on any CORDEX data. However, some CORDEX datasets can have a restriction to be used for non-commercial research and educational purposes only. To download CORDEX data through ESGF all users have to first sign up to the CORDEX Research or CORDEX Commercial group (https://www.nsc.liu.se/storage/esgf-datanode/).

Users in CORDEX Commercial group can download only unrestricted CORDEX simulations. A list with Terms of Use for all CORDEX models can be found here. Note that some RCMs can be missing in this list, for further questions on this please contact therespective RCM groups. There are also regional portals. Terms of Use for these may differ and might be found at the portals or otherwise contact the relevant Point of Contact.

Is there a formula or algorithm I can apply to convert the real world co-ordinates to rotated ones for extraction of data?
RCMs use a number of different native projection/coordinate systems that include for example the rotated coordinates, Mercator and Lambert Conic Conformal (LCC) projections. The rotated coordinate system is the most common one and is used in many CORDEX RCMs.

In some CORDEX domains (e.g. Africa and MENA) there is no rotation but RCMs still use the rotated coordinates. In this case, the rotated coordinates coincide with geographical ones which is not the case for other CORDEX regions with rotation (e.g. Europe and South Asia).

One of the CORDEX archiving requirements is to provide both native RCM coordinates (rotated, Lambert Conformal etc.) and the geographical ones. It’s supposed that all CORDEX RCMs should provide the 1D native coordinates (rlon/rlat for the rotated coordinates and x/y for the Mercator and LCC ) and additionally the usual 2D geographical coordinates (lon/lat). The 2D lon/lat coordinates are curvilinear for almost all CORDEX domains.

Note, that not all software packages support such double coordinates in the CORDEX netcdf files and some additional configuration can be necessary. The CDO tool (https://code.mpimet.mpg.de/projects/cdo/) can be used for converting the rotated coordinates or LCC projection to the geographical ones. However, this tool is for Linux-based system (command line).