The ERA5 dataset contains one (hourly, 31 km) high resolution realisation (referred to as 'reanalysis' or 'HRES') and a reduced resolution ten member ensemble (referred to as 'ensemble' or 'EDA'). The atmospheric model in the IFS is coupled to a land-surface model (HTESSEL), which produces parameters such as 2m temperature and soil temperatures, and an ocean wave model (WAM), the parameters of which are also designated as surface or single level parameters. 'Surface or single level' data are also available, containing 2D parameters such as precipitation, top of atmosphere radiation and vertical integrals over the entire depth of the atmosphere. Atmospheric data are available on these levels and they are also interpolated to 37 pressure, 16 potential temperature and 1 potential vorticity level(s) by FULL-POS in the IFS. For up to date information on ERA5, please consult the C3S Announcements on the Copernicus user forum.ĮRA5 is produced using 4D-Var data assimilation and model forecasts in CY41R2 of the ECMWF Integrated Forecast System (IFS), with 137 hybrid sigma/pressure (model) levels in the vertical and the top level at 0.01 hPa. Complete ERA5 data released so far covers the period from 1959 and continues to be extended forward in near real time.

Here we document the ERA5 dataset, which, eventually, will cover the period from January 1940 onwards.

Cdf files nasa documentation