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 variances and covariances on the original 60 model levels, as well as the variance of the surface pressure. All Variables are archived on the full n80 gaussian grid with a resolution of approximately 125 kilometers. The variances and covariances are produced with respect to the monthly means for each hour four synoptic hours (00, 06, 12 and 18 UTC) and for the diurnal mean.