UGAMP Data: ERA-40

The European Centre for Medium-Range Weather Forecasts (ECMWF) are currently producing a 44 year re-analysis, ERA-40, covering the period September 1957 to August 2002. The progress of production at the ECMWF can be found here while a summary of the data validated by the ECMWF can be found here. The assimilation system uses 3D-VAR while the forecasting model is based on an operational model from around the year 2000. The ERA-40 data are produced at a resolution of T159/N80/L60 extending from the ground to 0.1hPa. More documentation on ERA-40 can be found from the British Atmospheric Data Centre (BADC) here, and the ECMWF here. In order to extend the period covered by ERA-40 data, the latter can be used in conjunction with ECMWF operational data. By using these two datasets in tandem, we will have a dataset which extends from September 1957 to the present.

CGAM is extracting a subset of the ERA-40 data as it is produced by the ECMWF. It is being archived at Computer Services for Academic Research (CSAR) where it is available to the UGAMP community. The dataset contains mostly analyses, with some forecasts, in GRIB and NETCDF format. The GRIB data contain six hourly analyses at the surface and on model, pressure, isentropic and PV levels. The (daily) forecast data is confined to a few fields at the surface. For the ERA-40 period the data is archived at full resolution and grid point data is held on the reduced gaussian grid. For operational data the resolution has been reduced to match the ERA-40 resolution and grid point data is held on the full gaussian grid. All the GRIB data, except for the model level fields, are being converted to NETCDF format using XCONV. In addition, monthly mean fields are being produced from the NETCDF data using the nco utilities. Monthly climatologies for the years 1958 to 2001 have been produced from the monthly mean data.

Access to the ERA-40 data is restricted: before using the data, users must get an account with the BADC and then get permission to use ERA-40, ERA-15 and ECMWF operational data. Users should then forward to paulb@met.rdg.ac.uk the email from the BADC informing them that permission has been granted for them to use these datasets, and ask to be put into the badc and era40 groups.

Availability

GRIB Content

NETCDF Content

CSAR Archive

CGAM, Department of Meteorology,
University of Reading,
Earley Gate, PO Box 243,
Reading RG6 6BB, UK

Tel: +44 (0) 118 378 8315
Fax: +44 (0) 118 378 8316