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Restrictions | Details | Caveats | File Naming | Citation | References | Original Source | Contact

NCEP/NCAR Reanalysis 1: Surface

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
  • These variables are instantaneous values at the reference time.

Spatial Coverage:

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

Levels:

  • Surface or near the surface (.995 sigma level), or entire atmosphere (eatm)
  • Also, precipitable water is included here, because it is a 3-D file on a 2.5 degree grid, but it is not a surface value, but rather for the entire atmospheric column

Update Schedule:

  • Daily
Variable Statistic Level Download File Create Plot/Subset
Air Temperature 4-times Daily sig995 see list plot
Air Temperature Daily sig995 see list plot
Air Temperature Monthly Mean sig995 air.mon.mean.nc plot
Surface lifted index 4-times Daily surface see list plot
Surface lifted index Daily surface see list plot
Best (4-layer) lifted inde 4-times Daily surface see list plot
Best (4-layer) lifted index Daily surface see list plot
Omega (vertical velocity) 4-times Daily sig995 see list plot
Omega (vertical velocity) Daily sig995 see list plot
Potential temperature 4-times Daily sig995 see list plot
Potential temperature Daily sig995 see list plot
Precipitable water 4-times Daily eatm see list plot
Precipitable water Daily eatm see list plot
Precipitable water Monthly Mean eatm pr_wtr.mon.mean.nc plot
Pressure 4-times Daily surface see list plot
Pressure Daily surface see list plot
Pressure Monthly Mean surface pres.mon.mean.nc plot
Relative humidity 4-times Daily sig995 see list plot
Relative humidity Daily sig995 see list plot
Relative humidity Monthly Mean sig995 rhum.mon.mean.nc plot
Sea level pressure 4-times Daily sea-lvl see list plot
Sea level pressure Daily sea-lvl see list plot
Sea level pressure Monthly Mean sea-lvl slp.mon.mean.nc plot
U-wind 4-times Daily sig995 see list plot
U-wind Daily sig995 see list plot
U-wind Monthly Mean sig995 uwnd.mon.mean.nc plot
V-wind 4-times Daily sig995 see list plot
V-wind Daily sig995 see list plot
V-wind Monthly Mean sig995 vwnd.mon.mean.nc plot
Geopotential hgt time invariant Surface hgt.sfc.nc plot
Land-sea mask time invariant Surface land.nc 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:

    Archive parameters: File names are composed of variable abbreviations, level, and year: (variable).(level).(year).nc

b

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 450 files currently
  • Files are 30 Mbytes per variable per year
  • Current total of 13.8 Gbytes for 4xDaily and 3.4 Gbytes 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