ERA5 is a climate reanalysis dataset, covering the period 1950 to present. ERA5 is being developed through the Copernicus Climate Change Service (C3S).
ERA5 data is open access and free to download for all uses, including commercial use through the C3S Climate Data Store.
Data processing for ERA5 is carried out by ECMWF, using ECMWFS' Earth System model IFS, cycle 41r2. The name ERA refers to 'ECMWF ReAnalysis', with ERA5 being the fifth major global reanalysis produced by ECMWF (after FGGE, ERA-15, ERA-40, ERA-Interim). The next reanalysis, ERA6, is planned for around 2020.
ERA5 is currently available for the period 1979 to present (~3 months in arrears). For the further release plan please see here.
ECMWF and Copernicus also intend to make available all observations that were used in ERA5 plus their feedback. That will be done via the Observation Feedback Archive; a prototype for ERA-20C can be found at: http://apps.ecmwf.int/datasets/data/era20c-ofa/
ERA5 contains most parameters available in it predecessor, ERA-Interim; and ERA5 has some additional parameters. ERA5 uses the same 37 pressure levels as ERA-Interim.
In ERA5, 10 ensemble members, and also ensemble mean and spread for all parameters and levels are archived. The temporal resolution for the ensemble data is 3-hourly (rather than hourly for the deterministic ERA5 product). All ensemble members are made available , as well as mean and spread.
ERA5 data is archived in the GRIB file format.
Please see ERA5 documentation for full details.
For further details please see this article from the ECMWF Newsletter 147, page 7: