ERA-Interim is a global atmospheric reanalysis that is available from 1 January 1979 to 31 August 2019. It has been superseded by the ERA5 reanalysis.

The data assimilation system used to produce ERA-Interim is based on a 2006 release of the IFS (Cy31r2). The system includes a 4-dimensional variational analysis (4D-Var) with a 12-hour analysis window. The spatial resolution of the data set is approximately 80 km (T255 spectral) on 60 levels in the vertical from the surface up to 0.1 hPa. 

For a detailed documentation of the ERA-Interim Archive  see Berrisford et al. (2011)

An open-access journal article describing the ERA-Interim reanalysis is available from the Quarterly Journal of the Royal Meteorological Society. Additional details of the modelling and data assimilation system used to produce ERA-Interim can be found in the IFS documentation Cy31r1. We are aware of several quality issues with ERA-Interim data.