On this page: Temporal Coverage | Spatial Coverage | Levels | Update Schedule | Download/Plot Data | Analysis Tools
Restrictions | Details | Caveats | File Naming | Citation | References | Original Source | Contact

NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables

As of 2014/10/03, the NCEP/NCAR Reanalysis 1 is being updated at PSD. Some products are catching up and we don't yet know when normal distribution will return at NCEP.
=========================================================================================================================================================================

We will be transitioning the data files from netCDF3 to netCDF4-classic format on Monday Oct 20th. 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 units to use 1800 as the origin year for udunits. This should prove easier for users. A sample file:uwnd.2013.net4.nc is available for testing.

Brief Description:

  • NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables..

Temporal Coverage:

  • Daily and Monthly Values for 1948/01 - 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:

    Search keywords:

  • Tropopause

Update Schedule:

  • Monthly
Variable Statistic Level Download File Create Plot/Subset File Metadata
Air Temperature Monthly Means Tropopause air.mon.mean.nc plot File Metadata
Air Temperature Monthly Long Term Means Tropopause air.mon.ltm.nc plot File Metadata
Air Temperature Monthly Means Tropopause air.tropp.mon.mean.nc plot File Metadata
Air Temperature Monthly Long Term Means Tropopause air.tropp.mon.ltm.nc plot File Metadata
Air Temperature Daily Long Term Means Tropopause air.tropp.day.1981-2010.ltm.nc plot File Metadata
Air Temperature 4X Daily Long Term Means Tropopause air.tropp.4Xday.1981-2010.ltm.nc plot File Metadata
Pressure Monthly Means Tropopause pres.mon.mean.nc plot File Metadata
Pressure Monthly Long Term Means Tropopause pres.mon.ltm.nc plot File Metadata
Pressure Monthly Means Tropopause pres.tropp.mon.mean.nc plot File Metadata
Pressure Monthly Long Term Means Tropopause pres.tropp.mon.ltm.nc plot File Metadata
Pressure Daily Long Term Means Tropopause pres.tropp.day.1981-2010.ltm.nc plot File Metadata
Pressure 4X Daily Long Term Means Tropopause pres.tropp.4Xday.1981-2010.ltm.nc plot File Metadata

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:

  • None

Related File Naming & Structure Information:

File Names:

  • var.time.stat.nc   (In directory: /Datasets/ncep.reanalysis.derived/)
  • Files are available by anonymous FTP from ftp.cdc.noaa.gov in /Datasets/ncep.reanalysis.derived/tropopause/.
  • Archive parameters: File names are generally composed of variable abbreviations, averaging period and statistic. Averaging periods include "day" and "mon". Statistics include "mean", "ltm"(long-term mean), "inter.std" (interannual standard deviation). (variable).(averaging period).(statistic).nc

OpenDap File Names:

  • http://www.esrl.noaa.gov/psd/thredds/dodsC/Datasets/ncep.reanalysis.derived/tropopause/var.time.stat.nc   

Dataset Format and Size:

  • PSD standard NetCDF xx (packed).
  • All data are stored in netCDF files
  • The data are divided by variable and year into separate files
  • There are 48 files currently
  • Files range in size from 167 Kbytes to 26 Mbytes
  • Current total of 377 Mbytes

Missing Data:

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

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 Derived 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 Derived 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 Derived 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