The ECMWF Re-Analysis (ERA40) is a global atmospheric analysis of many conventional observations and satellite data streams for the period Sept,1957- Aug,2002. There are numerous data products that are separated into dataset series' based on resolution, vertical coordinate reference, and likely research applications. Descriptions of the series organization and direct links to information about all ERA40 products are available.

This dataset contains monthly means for 9 variables on the original 60 model levels, as well as surface geopotential and log of surface pressure. Variables are archived at T159 spectral resolution in spherical harmonics or the reduced n80 gaussian grid with a resolution of approximately 125 kilometers. Synoptic monthly means have been computed for each analysis hour and a diurnal mean has also been computed. Both means are only computed for the 6 hour forecast.

The ERA-Interim data from ECMWF is an update to the ERA-40 project. The ERA-Interim data starts in 1989 and has a higher horizontal resolution (T255, N128 nominally 0.703125 degrees) than the ERA-40 data (T159, N80 nominally 1.125 degrees). ERA-Interim is based on a more current model than ERA-40 and uses 4-D VAR (as apposed to 3-D VAR in ERA-40). ECMWF will continue to run the ERA-Interim model in near real time thru at least 2010, and possibly longer. This data is available in ds627.0.