ECMWF maintains an archive of monthly means data from the atmospheric model archive. Since the resolution and internal representation of the archive may change according to changes in ECMWF's operational practice, data services associated with these data sets include the provision of interpolation to requested resolutions, representations and areas.

The monthly means archive is subdivided into eight data sets:

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

The Atmospheric Data Sets provide access to the atmospheric model monthly means data archived at ECMWF. This archive includes analysis, first-guess (short term forecasts) and forecast data. Analysis and forecast data are available on the surface, pressure levels and model levels. The first-guess archive is only available for pressure and model level data.

The 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.

A full extraction service is supported, 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.

05.09.2008