Mention tools for downloading datasets in documentation

[bouweandela]

There are several convenient tools available for obtaining (observational) datasets. It would be good to mention those in the section on obtaining data.

For example:

• Copernicus Climate Data Store: https://pypi.org/project/cdsapi/
• ECMWF Data: https://pypi.org/project/ecmwf-api-client/
• ERA5 command line tool: https://era5cli.readthedocs.io
• ESGF data: esgf-pyclient, integrated into esmvaltool with the esmvaltool run --offline=False command
• ESGF data: Synda: http://prodiguer.github.io/synda/
• Public ESGF data: Sproket: https://github.com/ESGF/sproket

[valeriupredoi]

• ESGF-CEDA (and all the others: DKRZ, LLNL): https://esgf-index1.ceda.ac.uk/projects/esgf-ceda/ (for model data)
• concrete instructions how to wget model data off ESGF: https://www.earthsystemcog.org/projects/cog/doc/wget

[bouweandela]

Related to #1657

[bouweandela]

Removed from this milestone because @jvegasbsc is working on this topic in #1657, but it seems unlikely that there will be time to include that in v2.0.0.

[SarahAlidoost]

I found that "--synda-download" option is removed see this issue. But the documentation has not been updated, see Running a recipe and synda.

[bouweandela]

But the documentation has not been updated, see Running a recipe

Thanks for reporting this @SarahAlidoost, I hadn't spotted that mention of the command. In fact, that whole section should maybe be removed because running is part of ESMValCore. I'll make a pull request to update it. The other mention of Synda seems fine, people can still use Synda to maintain their own data collection, even if this is not integrated with the tool.

[bouweandela]

@SarahAlidoost A pull request is now available (#2432), it would be great if you could have a look