Restrictions | Details | Caveats | File Naming | Citation | References | Original Source | Contact
NCEP/NCAR Reanalysis 1
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.
- NCEP/NCAR Reanalysis 1
- 4-times daily, daily and monthly values for 1948/01/01 to present
- Long term monthly means, derived from data for years 1981 - 2010
- 2.5 degree latitude x 2.5 degree longitude global grid ( 144x73)
- 90N - 90S, 0E - 357.5E
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|
|Air Temperature||Daily||Tropopause||see list|
|Air Temperature||Monthly Mean||Tropopause||see list|
|Pressure||4-times Daily||Tropopause||see list|
|Pressure||Monthly Mean||Tropopause||see list|
- 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.
- Please read the problem list before using the data.
- 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 is flagged with a value of 32767s or 9.36e36f..
- 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!
- March, 1996 BAMS
- NOAA National Center for Environmental Prediction
Physical Sciences Division: Data Management
Boulder, CO 80305-3328