ECMWF Interim Reanalysis Data Archive

The interim reanalysis project ERA Interim will cover the period from 1979 onwards, overlapping the earlier ECMWF 40 year reanalysis.

The project is in near real-time production. Data will be added in monthly periods about 3 to 4 months after the end of the month being added. See details for up-to-date information about data availability.

This Level III-B archive is subdivided into three classes of data sets:

• Atmospheric daily data
• Atmospheric monthly mean data
• Wave model data

The data sets are based on quantities analysed or computed within the ERA Interim data assimilation scheme or from forecasts based on these analyses.

Data Server

• Much ERA Interim data is available from the ECMWF Data Server at no charge for research usage.
• Data up to the end of last year of the ERA Interim data from the Data Server can be supplied by ECMWF Data Services with new years being added as they become available.

Atmospheric daily data

• These data sets provide access to most of the data from the ERA Interim atmospheric model archived at ECMWF.
• They include analysis, forecast accumulation and forecast data.
  • Analysis data are available for surface, pressure, model, isentropic and potential vorticity levels.
  • Daily forecast data are available for surface, pressure and model levels.

Atmospheric Monthly Means

• The atmospheric monthly means data sets provide monthly means and monthly means of daily means of analysis and forecast data.
• Analysis data are available for surface, pressure, model, isentropic and potential vorticity levels.
• Monthly mean forecast data are available for surface, pressure and model levels.

Wave

• These data sets contain analysis and forecast data from the ERA Interim wave model.

The ERA Interim archive is currently maintained using the WMO FM 92-IX Ext GRIB (grid in binary) form of data representation, with ECMWF local versions of GRIB Table 2. All fields of data are global within the archive except for Mediterranean wave model data.

Data are stored in FM 92 GRIB using sufficient bits to ensure that the grid point values can be retrieved to an accuracy consistent with the analysis methods used

A full extraction service is provided, enabling users to obtain sub-areas of data and data at various resolutions on regular Gaussian or latitude/longitude grids, or as spherical harmonics with selected triangular truncation. All extracted data are delivered using the GRIB representation.