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NCEP/NCAR Reanalysis 1: Surface Flux

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.
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We have transitioned 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. The exception to the above are the spectral coefficients files, which are still packed.

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: Surface Flux data

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:

  • T62 Gaussian grid with 192x94 points
  • 88.542N-88.542S, 0E-358.125E

Levels:

  • Surface or near the surface

Update Schedule:

  • Daily
  • The exceptions to the daily updating are NLWRS and NSWRS. The reason is that NCEP does not make them available via the same channel as the others. This other NCEP channel usually appears with the NLWRS and NSWRS data for the previous month sometime in the first ten days of the new month. The files in our archive are updated usually within 24 hours (barring weekends) of NCEP making it available to us.

Variable Statistic Level Download File Create Plot/Subset
Geopotential Height * Surface hgt.sfc.gauss.nc plot

* = no year in file name

These variables (air.2m - weasd) are forecasts valid 6 hours after the reference time:

Variable Statistic Level Download File Create Plot/Subset
Air Temperature 2m 4-times Daily 2m see list plot
Air Temperature 2m Daily 2m see list plot
Ice concentration 4-times Daily Surface see list plot
Ice concentration Daily Surface see list plot
Potential evaporation rate 4-times Daily Surface see list plot
Potential evaporation rate Daily Surface see list plot
Pressure 4-times Daily Surface see list plot
Pressure Daily Surface see list plot
Water Runoff 4-times Daily Surface see list plot
Water Runoff Daily Surface see list plot
Surface Roughness 4-times Daily Surface see list plot
Surface Roughness Daily Surface see list plot
Specific humidity at 2 meter 4-times Daily 2m see list plot
Specific humidity at 2 meter Daily 2m see list plot
Soil moisture (0-10cm) 4-times Daily 0-10cm see list plot
Soil moisture (0-10cm) Daily 0-10cm see list plot
Soil moisture (10-200cm) 4-times Daily 10-200cm see list plot
Soil moisture (10-200cm) Daily 10-200cm see list plot
Skin Temperature 4-times Daily Surface see list plot
Skin Temperature Daily Surface see list plot
Temperature of 0-10cm layer 4-times Daily 0-10cm see list plot
Temperature of 0-10cm layer Daily 0-10cm see list plot
Temperature of 10-200cm layer 4-times Daily 10-200cm see list plot
Temperature of 10-200cm layer Daily 10-200cm see list plot
Temperature at 300cm 4-times Daily 300cm see list plot
Temperature at 300cm Daily 300cm see list plot
U-wind at 10 m 4-times Daily 10m see list plot
U-wind at 10 m Daily 10m see list plot
V-wind at 10 m 4-times Daily 10m see list plot
V-wind at 10 m Daily 10m see list plot
Water equiv. of snow depth 4-times Daily Surface see list plot
Water equiv. of snow depth Daily Surface see list plot

 

These variables are six-hour hindcasts from the reference time in the file:

Variable Statistic Level Download File Create Plot/Subset
Maximum temperature at 2m 4-times Daily 2m see list plot
Maximum temperature at 2m Daily 2m see list plot
Minimum temperature at 2m 4-times Daily 2m see list plot
Minimum temperature at 2m Daily 2m see list plot

 

These variables (cfnlf.sfc - vgwd) are 6 hour averages starting at the reference time:

Variable Statistic Level Download File Create Plot/Subset
Cloud forcing net longwave flux 4-times Daily Surface see list plot
Cloud forcing net longwave flux Daily Surface see list plot
Cloud forcing net solar flux 4-times Daily Surface see list plot
Cloud forcing net solar flux Daily Surface see list plot
Convective precipitation rate 4-times Daily Surface see list plot
Convective precipitation rate Daily Surface see list plot
Clear sky downward longwave flux <4-times Daily Surface see list plot
Clear sky downward longwave flux Surface see list plot
Clear sky downward solar flux 4-times Daily Surface see list plot
Clear sky downward solar flux Daily Surface see list plot
Downward longwave radiation flux 4-times Daily Surface see list plot
Downward longwave radiation flux Daily Surface see list plot
Downward solar radiation flux 4-times Daily Surface see list plot
Downward solar radiation flux Daily Surface see list plot
Ground heat flux 4-times Daily Surface see list plot
Ground heat flux Daily Surface see list plot
Latent heat net flux 4-times Daily Surface see list plot
Latent heat net flux Daily Surface see list plot
Near IR beam downward solar flux 4-times Daily Surface see list plot
Near IR beam downward solar flux Daily Surface see list plot
Near IR diffuse downward solar flux 4-times Daily Surface see list plot
Near IR diffuse downward solar flux Daily Surface see list plot
Net longwave radiation 4-times Daily Surface see list plot
Net longwave radiation Daily Surface see list plot
Net shortwave radiation 4-times Daily Surface see list plot
Net shortwave radiation Daily Surface see list plot
Precipitation rate 4-times Daily Surface see list plot
Precipitation rate Daily Surface see list plot
Sensible heat net flux 4-times Daily Surface see list plot
Sensible heat net flux Daily Surface see list plot
Momentum flux (zonal) 4-times Daily Surface see list plot
Momentum flux (zonal) Daily Surface see list plot
Zonal gravity wave stress 4-times Daily Surface see list plot
Zonal gravity wave stress Daily Surface see list plot
Upward longwave radiation flux 4-times Daily Surface see list plot
Upward longwave radiation flux Daily Surface see list plot
Upward solar radiation flux 4-times Daily Surface see list plot
Upward solar radiation flux Daily Surface see list plot
Visible beam downward solar flux 4-times Daily Surface see list plot
Visible beam downward solar flux Daily Surface see list plot
Visible diffuse downward solar flux 4-times Daily Surface see list plot
Visible diffuse downward solar flux Daily Surface see list plot
Momentum flux (meridional) 4-times Daily Surface see list plot
Momentum flux (meridional) Daily Surface see list plot
Meridional gravity wave stress 4-times Daily Surface see list plot
Meridional gravity wave stress Daily Surface see list plot
Land-sea mask 4-times Daily Surface see list plot

* = no year in file name

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:

  • Please read the problem list before using the data.
  • The netCDF data files for the NCEP/NCAR Reanalysis variable PEVPR (files named pevpr.sfc.gauss.YY.nc or pevpr.sfc.gauss.YYYY.nc) may have incorrect units for the pevpr (Potential Evaportion Rate) variable.The correct units are watts per meter squared (W/m^2).
  • The skt.sfc files contain skin temperature as described in the March, 1996 BAMS article. As such, over land and sea ice, the temperature is a prognostic variable. Over open water, the skin temperature is fixed at its initial value; i.e., the Reynolds SST as seen by the model. The Reynolds' SST analyses were done weekly and the reconstructed SST done monthly. The analyses were linearly interpolated to daily values which were used for all four analyses.

Related File Naming & Structure Information:

File Names:

  • Archive parameters: File names are composed of variable abbreviations, level, and year: (variable).(level).gauss.(year).nc
  • See individual sections. Data in /Datasets/ncep.reanalysis/, Datasets/ncep.reanalysis.dailyavgs/, /Datasets/ncep.reanalysis.derived/

Dataset Format and Size:

  • PSD standard NetCDF most are (packed).
  • There are 1,720 files currently
  • Files are 52 Mbytes per variable per year
  • Current total of 90.4 Gbytes for 4xDaily and 22.6 Gbytes for daily averages
  • The data are divided by variable and year into separate files
  • 4x daily data are available from ftp.cdc.noaa.gov in /Datasets/ncep.reanalysis/surface_gauss/.
  • The 4x data files are quite large, so you may only be able to download them if you have a fast network connection.
  • Daily averages are available from ftp.cdc.noaa.gov in /Datasets/ncep.reanalysis.dailyavgs/surface_gauss/.
  • 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 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