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NCEP/NCAR Reanalysis 1

At this time (2014/09/29), the NCEP/NCAR Reanalysis is not being updated at PSD as NCEP has halted their distribution. Any of our products or web-tools that use this data will be impacted. Data will be updated when it becomes available. We have no further information as to when that might be.
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We will be transitioning the data files from netCDF3 to netCDF4-classic format. As a result, the files will be compressed instead of being packed with a scale and offset. As with any netCDF4 file, the NetCDF library will perform the uncompression. We expect the files to be read faster, depending on the application you are using. Values may differ slightly because of precision issues. Please let us know if you run into any problems after first reading our netCDF4 doc . We are also changing the time acces to use 1800 as a reference date for udunits. This should prove easier for users.

Other Grid Types: NCEP Reanalysis Main Page | Pressure Level Data | Surface Data | Surface Flux Data | Other Flux Data |Spectral Coefficents Data | Tropopause Data

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:

  • 2.5 degree latitude x 2.5 degree longitude global grid ( 144x73)
  • 90N - 90S, 0E - 357.5E

Levels:

  • Tropopaise

Update Schedule:

  • Daily

Note: These variables are instantaneous values at the reference time.

Variable Statistic Level Download File Create Plot/Subset
Air Temperature 4-times Daily Tropopause see list plot
Air Temperature Daily Tropopause see list plot
Air Temperature Monthly Mean Tropopause see list plot
Pressure 4-times Daily Tropopause see list plot
Pressure Daily Tropopause see list plot
Pressure Monthly Mean Tropopause see list plot

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 PSD 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.

Caveats:

Related File Naming & Structure Information:

File Names:

  • See individual sections. Data in /Datasets/ncep.reanalysis/, Datasets/ncep.reanalysis.dailyavgs/, /Datasets/ncep.reanalysis.derived/
  • Archive parameters: File names are composed of variable abbreviations and year: (variable).tropp.(year).nc
  • On PSD computers the 4x daily data are in the directory /Datasets/nmc.reanalysis/tropopause.
  • On PSD computers the daily average data are in the directory /Datasets/ncep.reanalysis.dailyavgs/tropopause.

Dataset Format and Size:

  • PSD standard NetCDF most are (packed).
  • All data are stored in netCDF files
  • The data are divided by variable and year into separate files
  • There are 82 files currently
  • Each file is about 31 megabytes.
  • Current total of 2.5 Gbytes for 4xDaily and 628 Mbytes for daily averages

Missing Data:

  • Missing data is flagged with a value of 32767s or 9.36e36f..

Citation:

  • For dataset source, please cite:Kalnay et al.,The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470, 1996.
  • Please note: If you acquire NCEP Reanalysis data products from PSD, we ask that you acknowledge us in your use of the data. This may be done by including text such as NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/ in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSD to justify keeping the NCEP Reanalysis data set freely available online in the future. Thank you!

References:

  • March, 1996 BAMS

Original Source:

  • NOAA National Center for Environmental Prediction

Contact:

  • Physical Sciences Division: Data Management
    NOAA/ESRL/PSD
    325 Broadway
    Boulder, CO 80305-3328
    esrl.psd.data@noaa.gov