Release of ERA5-Land-T data and new selection limit in place

Announcements C3S - Announcements
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1

We would like to announce the release of ERA5-Land-T today, Monday 19th December 2022. The data is available from the Climate Data Store

ERA5-Land-T provides preliminary data for ERA5-Land on a daily basis, with a 5-day delay from real time. 
This enables you to retrieve ERA5-Land data up to 5 days ago (much improved compared to the 2-3 months delay for the release of validated ERA5-Land data).

The nature of preliminary data implies that usually ERA5-Land data younger than 2-3 months has the potential of being revised 
in case of any issue found. If such issue were to be found however, it would be documented and communicated to users via the mailing list and on our User Forum.

If you want to find out whether or not the data you downloaded contains ERA5-Land-T, you can follow the instructions described in the ERA5-Land data documentation.

Please be aware that there is a new selection limit in place that allows to download no more than a month at the time in a single request (more specifically, no more than a 1000 items at a time).

Please note, if users have their own version of the ERA5 daily statistics application, they must take a fresh copy if they wish to use ERA5-Land-T data. A fresh copy of the workflow can be copied from here: https://cds.climate.copernicus.eu/toolbox-editor/user-apps/app-c3s-daily-era5-statistics

If you have any questions, please raise a query via our Support Portal. 

Best regards,

ECMWF Support

2

Could you please explain why download from ERA5-Land is now limited to 1000 items? This is a new and very severe restriction, it makes it very difficult to access data covering long time-periods. ERA5 is not limited in this way, so is why ERA5-Land?

Andreas

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Stricter selection limits on ERA5-Land were unfortunately necessary as the large requests were causing backlogs in the Climate Data Store (CDS) queueing system. Since imposing the limits a much higher level of service across the system was achieved, a 20-50% increase in quantity of data delivered per day. 

It became obvious quite quickly that this limit impacted our users more than anticipated and so the Climate Data Store (CDS) team looked into ways of improving the situation while preserving compute resources on the CDS.

We are pleased to inform ERA5-Land users that the limit has been reviewed and increased from 1,000 to 12,000 fields which means that users may now download up to 12 variables per month at once. Using an API script, users may loop through months and years. There are API examples for doing this in the CDS Documentation at: https://confluence.ecmwf.int/display/CKB/Climate+Data+Store+%28CDS%29+documentation#ClimateDataStore(CDS)documentation-CDSAPIandCDSToolboxexamples

While many users may prefer to download the data in NetCDF format, we strongly recommend that data is downloaded in its native format (GRIB) to avoid disappointment (the GRIB to NetCDF conversion is likely to fail on larger requests unfortunately). Keep in mind that with downloading data on a month by month basis in GRIB format, you may then concatenate say 12 monthly GRIB files to make one yearly GRIB file (see our Knowledge Base article on (How to merge multiple GRIB or NetCDF files).

Regards, 

ECMWF Support