The CDS dataset "Essential climate variables for assessment of climate variability from 1979 to present" ( https://cds.climate.copernicus.eu/cdsapp#!/dataset/ecv-for-climate-change?tab=overview ) has been significantly updated.
The changes are:
1. The dataset now includes variables from ERA5 as well as ERA-Interim;
2. A "monthly mean" product type is available;
3. Filenames, grids and units have been harmonised between the data sources;
4. Some changes have been applied to ERA-Interim 2m temperature fields for time periods before 2002 to address issues with the data.
Regards,
Kevin
C3S User Support