Limitation change on netCDF ERA5 requests

[Michela]

As many users will have already noticed, a change has recently been implemented in some ERA5 datasets with respect to the retrieval of data in NetCDF format versus GRIB format.

The native ERA5 data is in GRIB format. When you download the data in NetCDF, additional processing is required which impacts the performance of the system. For this reason, a smaller amount of data in NetCDF can be retrieved rather than in GRIB format.

You can check whether your request is within scope using the data download form on the Climate Data Store (CDS) and update your API script accordingly**.

The new constraints have been applied to the following ERA5 family datasets:

• ERA5 hourly data on single levels from 1940 to present
• ERA5 hourly data on pressure levels from 1940 to present
• ERA5 monthly averaged data on single levels from 1940 to present
• ERA5 monthly averaged data on pressure levels from 1940 to present
• ERA5-Land hourly data from 1950 to present
• ERA5-Land monthly averaged data from 1950 to present

We will update this topic should other CDS datasets be added to the list above or changes to these constraints be made.

ECMWF Support

[User_figuera_at_sistema_d]

Thanks for the update — though once again, it comes only after the changes have been implemented. This reactive communication style seems to be the norm lately, which is increasingly difficult for those of us relying on CDS in automated workflows.

While there’s no mailing list (yet), it’s still surprising that with all the user data already available, a more direct or proactive communication method hasn’t been considered. Relying solely on forum posts after-the-fact doesn’t exactly support smooth operations on our side.

A heads-up in advance — even just a basic notification system for planned changes — would help a lot in reducing unnecessary troubleshooting and downtime.

Hopefully this is something that can finally be prioritized — it’s clearly not a new concern.