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NCEP/NCAR Reanalysis 1: Summary

We have transitioned the data files from netCDF3 to netCDF4-classic format on Monday Oct 20th, 2014.

Brief Description:

  • NCEP/NCAR Reanalysis 1

Temporal Coverage:

  • 4-times daily, daily and monthly values for 1948/01/01 to present
  • Long term monthly means, derived from data for years 1981 - 2010

Spatial Coverage:

  • Global Grids


  • 17 Pressure level and 28 sigma levels. N/A

Update Schedule:

  • Daily
We have separated the data documentation into seven sections:

Usage Restrictions:

  • None

Detailed Description:

  • The NCEP/NCAR Reanalysis 1 project is using a state-of-the-art analysis/forecast system to perform data assimilation using past data from 1948 to the present. A large subset of this data is available from PSL in its original 4 times daily format and as daily averages. However, the data from 1948-1957 is a little different, in the regular (non-Gaussian) gridded data. That data was done at 8 times daily in the model, because the inputs available in that era were available at 3Z, 9Z, 15Z, and 21Z, whereas the 4x daily data has been available at 0Z, 6Z, 12Z, and 18Z. These latter times were forecasted and the combined result for this early era is 8x daily. The local ingestion process took only the 0Z, 6Z, 12Z, and 18Z forecasted values, and thus only those were used to make the daily time series and monthly means here.


Related File Naming & Structure Information:

File Names:

  • See individual sections. Data in /Datasets/ncep.reanalysis/, Datasets/ncep.reanalysis.dailyavgs/, /Datasets/ncep.reanalysis.derived/
  • Data can be ftp'd from ftp.cdc.noaa.gov

Dataset Format and Size:

  • PSL standard NetCDF most are (packed).
  • If you would like datasets on a media such as tape, you will need to get them from another institution. NCAR (link) provides such a service for their datasets.

Missing Data:

  • Missing data is flagged with a value of -9.96921e+36f.


To cite data-sets obtained from PSL, please cite the both the publication listed, if any, and a dataset access citation.

  • Publication: The NCEP/NCAR 40-Year Reanalysis Project: March, 1996 BAMS
  • Data Access: National Centers for Environmental Prediction/National Weather Service/NOAA/U.S. Department of Commerce. 1994, updated monthly. NCEP/NCAR Global Reanalysis Products, 1948-continuing. Research Data Archive at NOAA/PSL: /data/gridded/data.ncep.reanalysis.html.


Original Source:


  • Physical Sciences Laboratory: Data Management
    325 Broadway
    Boulder, CO 80305-3328