This dataset contains 56 surface and single level variables on an equally spaced global 2.5 degree latitude-longitude grid. All variables are reported 4x a day. 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. 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 [http://rda.ucar.edu/datasets/ds627.0].