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.

DS124.1 represents a new data set implemented and computed by NCAR's Data Support Section, and forms a substantial part of ongoing efforts to produce an archive of selected segments of ERA-40 on a standard transformation grid. In this case, ERA-40 upper air variables on 23 pressure levels have been transformed from either spherical harmonics (geopotential, temperature, vertical pressure velocity, vorticity, divergence, relative humidity), or a reduced N80 Gaussian grid (potential vorticity, specific humidity, ozone mass mixing ratio), to a 256x128 regular Gaussian grid at T85 spectral truncation. In addition, horizontal wind components have been derived from spectral vorticity and divergence and also archived on a T85 Gaussian grid. All fields are available 4x daily (00,06,12 and 18 UTC). All scalar fields have been transformed using routines from the ECMWF EMOS library, whereas the horizontal winds have been obtained using NCAR's Spherepack library. The choice of a T85 Gaussian grid was based on considerations of limiting the volume of new data generated to a moderate level, and to match the horizontal resolution of the Community Atmosphere Model (CAM) component of NCAR's Community Climate System Model (CCSM).

Sub-setting of DS124.1 is available to registered users of DSS ERA-40 data. Users may select a set of variables, and designate pressure levels, and start and end dates, for each variable. Output, in GRIB or netCDF, can be retrieved via restricted ftp.