This site provides data from the 20th Century Reanalysis Project. The new version 3 offers temperature, pressure, humidity, wind, and many other fields in 75 km sections all around the world from 1836 to 2015 (1806 to 1835 extended experimentally), every 3 hours, based on historical data. For version 3, the ensemble mean and standard deviation for each value were calculated over a set of 80 analyses and short-term forecasts. The previous versions 2 and 2c, which used 56 ensemble members each and span 1871 to 2012 (1851 to 2014, respectively) are also available. Data for each of the ensemble members are also included here. The dataset consists of files in netCDF-4 format that are available for download from the National Energy Research Scientific Computing Center.

How to Download the Data

You can browse and download the data by clicking one of the Browse Data buttons below. This brings you to the data directory for a particular version of the data. For Version 3, data listing is only via HPSS. Clicking "Browse Data from New Version 3" will bring you to a top-level directory of 20CRv3 data, as well as a README. Click "everymember_anal_netcdf" to see analysis variables in NetCDF-4. Choose "subdaily" for 8-times daily data, "daily" for daily means, or "mnmean" for monthly means. From there, you will see all variables currently available. Click a particular variable name to see a list of tarballs (one per variable and year). Clicking a "*.tar" file will begin the download.

Clicking "Browse Data from Version 2c" or "Browse Data from Version 2" will bring you to directories with "analysis" and "first_guess" options. In the analysis or first_guess directory, you will find a directory for each variable calculated. Click a variable name to see a list of yearly files for that variable. From here, you can click the filename for one of the years (e.g., t850_1871.nc for air temperature at 850 hPa during 1871) to see detailed download options. You can also click the file size in the Download column to begin downloading the entire file over http. When viewing download options, you will see tabs for alternative download tools, such as Ferret, GrADs, IDL, and PyDap. Click a tab for command-line instructions. Daily averages and monthly averages are in the analysis.derived and first_guess.derived directories.

Browse Data from New Version 3 Browse Data from Version 2c Browse Data from Version 2


As an example, suppose you want to download surface air pressure data for 1871. For Version 3, click the "Browse Data" button. Follow the links to "everymember_anal_netcdf", then "subdaily", then "PRES". Finally, click "PRES_1871.tar" to begin downloading the tarball.

For Versions 2 and 2c, click the Browse Data button for the version you want to work with. Then follow the links to "analysis", then "ps". Click "ps_1871.nc" in the Filename column to get a form for specifying download options. Place a check mark in the box labeled "ps," and enter colon-separated start, step, and stop values for your desired ranges of time, location, and ensemble membership. To include a listing of available times, latitudes, longitudes, or ensemble members for this variable and year, check the corresponding box and enter the start, step, and stop values you'd like. Finally, click "Download data."

You can also grab Version 2 and 2c data from this site using wget. Here's how to do that for Version 2 data:

wget http://portal.nersc.gov/pydap/20C_Reanalysis_ensemble/
analysis/{variable}/{variable}_{year}.nc

And here's how to do that for Version 2c data:

wget http://portal.nersc.gov/pydap/20C_Reanalysis_version2c_ensemble/
analysis/{variable}/{variable}_{year}.nc

Here's an example:

wget http://portal.nersc.gov/pydap/20C_Reanalysis_version2c_ensemble/
analysis/cape/cape_1901.nc

Note that Version 3 uses different variable abbreviations than Versions 2 and 2c; see links in the sidebar.

Having trouble opening the data files? See netCDF4 Compatibility Issues.

Articles about the 20th Century Reanalysis Project

ASCR Newsletter:
Reanalysis Project targets once-and-future weather

Wired:
Transcending Time: Great Long-Term Datasets

Climate Central:
Old Weather is Shedding New Light on Climate

Collaborator Institutions

Cooperative Institute for Research in Environmental Sciences
National Oceanic and Atmospheric Administration
UK Met Office Hadley Centre, Atmospheric Circulation Reconstructions
over the Earth
Full List

Related Links

20th Century Reanalysis Project
Advancing Reanalysis collaborative website
Atmospheric Circulation Reconstructions over the Earth
Physical Sciences Laboratory, NOAA/ESRL
Cooperative Institute for Research in Environmental Sciences (CIRES)
National Energy Research Scientific Computing Center (NERSC)
National Center for Computational Sciences (NCCS), Jaguar

Contacts

Gilbert P. Compo
CIRES, University of Colorado at Boulder, and Physical Sciences Laboratory, National Oceanic and Atmospheric Administration
gilbert.p.compo at noaa.gov

Laura C. Slivinski
CIRES, University of Colorado at Boulder, and Physical Sciences Laboratory, National Oceanic and Atmospheric Administration
laura.slivinski at noaa.gov

Acknowledgment

The Twentieth Century Reanalysis Project used resources of the National Energy Research Scientific Computing Center managed by Lawrence Berkeley National Laboratory and of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and Contract No. DE-AC05-00OR22725, respectively. The NOAA-CIRES-DOE Twentieth Century Reanalysis version 3 also used resources of NOAA's Remotely Deployed High Performance Computing Systems.

Papers using the Twentieth Century Reanalysis Project datasets are requested to include the following text in their acknowledgments: "Support for the Twentieth Century Reanalysis Project dataset is provided by the U.S. Department of Energy, Office of Science Biological and Environmental Research (BER) program, by the National Oceanic and Atmospheric Administration Climate Program Office, and by the NOAA Physical Sciences Laboratory."

References

Compo, G.P., J.S. Whitaker, P.D. Sardeshmukh, N. Matsui, R.J. Allan, X. Yin, B.E. Gleason, R.S. Vose, G. Rutledge, P. Bessemoulin, S. Brönnimann, M. Brunet, R.I. Crouthamel, A.N. Grant, P.Y. Groisman, P.D. Jones, M. Kruk, A.C. Kruger, G.J. Marshall, M. Maugeri, H.Y. Mok, Ø. Nordli, T.F. Ross, R.M. Trigo, X.L. Wang, S.D. Woodruff, and S.J. Worley, 2011: The Twentieth Century Reanalysis Project. Quarterly J. Roy. Meteorol. Soc., 137, 1-28. DOI: 10.1002/qj.776.

Slivinski, L.C., G. P. Compo, J. S. Whitaker, P. D. Sardeshmukh, B. S. Giese, C. McColl, R. Allan, X. Yin, R. Vose, H. Titchner, J. Kennedy, L. J. Spencer, L. Ashcroft, S. Brönnimann, M. Brunet, D. Camuffo, R. Cornes, T. A. Cram, R. Crouthamel, F. Domínguez-Castro, J. E. Freeman, J. Gergis, E. Hawkins, P. D. Jones, S. Jourdain, A. Kaplan, H. Kubota, F. Le Blancq, T.-C. Lee, A. Lorrey, J. Luterbacher, M. Maugeri, C. J. Mock, G.W. K. Moore, R. Przybylak, C. Pudmenzky, C. Reason, V. C. Slonosky, C. A. Smith, B. Tinz, B. Trewin, M. A. Valente, X. L. Wang, C. Wilkinson, K. Wood, and P. Wyszyński, 2019: Towards a more reliable historical reanalysis: Improvements for version 3 of the Twentieth Century Reanalysis system. Quarterly J. Roy. Meteorol. Soc., in press. DOI: 10.1002/qj.3598.