ERA-Interim production stopped on 31st August 2019

For ERA-Interim (1st January 1979 to 31st August 2019) access through the ECMWF Web API stopped on 01 June 2023

Its successor ERA5 is available from the Climate Data Store (CDS) (What are the changes from ERA-Interim to ERA5?) and users are strongly advised to migrate to ERA5 (How to download ERA5).

For those users who still need access to ERA-Interim after 01 June 2023 (subject to further notice), they can do so via the Climate Data Store (CDS) API.

Through systematic increases of computing power, 4-dimensional variational assimilation (4D-Var) became feasible and part of ECMWF operations since 1997, paving the way to base ERA-Interim on 4D-Var (rather than 3D-Var as in ERA-40).

Enhanced computing power also allowed horizontal resolution to be increased from T159 (N80) to T255 (N128), and the latest cycle of the atmospheric model (IFS CY31r1 and CY31r2) to be used, taking advantage of improved model physics.

ERA-interim retains the same 60 model levels used for ERA-40 with the highest level being 0.1 hectopascal.

In addition, data assimilation of ERA-Interim also benefits from quality control that draws on experience from ERA-40, variational bias correction of satellite radiance data, and more extensive use of radiances with an improved fast radiative transfer model.

See ECMWF publication on ERA-40 for further details. An open-access journal article describing the ERA-Interim reanalysis is available from the Quarterly Journal of the Royal Meteorological Society.

This document has been produced in the context of the Copernicus Climate Change Service (C3S).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Delegation agreement signed on 11/11/2014). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt, the European Commission and the European Centre for Medium-Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.