20th Century Reanalysis
Using a state-of-the-art data assimilation system and surface pressure observations, the Twentieth Century Reanalysis Project is generating a six-hourly, four-dimensional global atmospheric dataset spanning 1871 to present to place current atmospheric circulation patterns into a historical perspective.
20th Century Reanalysis and PSD: The NCEP-NCAR Reanalysis product starts from 1948, leaving many important climate events such as 1930's dust bowl droughts uncovered. To expand the coverage of global gridded reanalyses, the 20th Century Reanalysis Project is an effort led by PSD and the University of Colorado CIRES Climate Diagnostics Center to produce a reanalysis dataset spanning the entire twentieth century, assimilating only surface observations of synoptic pressure, monthly sea surface temperature and sea ice distribution. The observations have been assembled through international cooperation under the auspices of the Atmospheric Circulation Reconstructions over the Earth initiative, and working groups of GCOS and WCRP. The Project uses a recently-developed Ensemble Filter data assimilation method which directly yields each six-hourly analysis as the most likely state of the global atmosphere, and also estimates uncertainty in that analysis. This dataset will provide the first estimates of global tropospheric and stratospheric variability spanning 1871 to present at six-hourly resolution (V2). The first version has global coverage spanning 1908-1958, and two degree longitude-latitude horizontal resolution (V1).
Recreating the Knickerbocker Storm of 1922: One of the deadliest snowstorms in U.S. history was the Knickerbocker Storm, a slow- moving blizzard that occurred on January 27-29, 1922 in the upper South and Middle Atlantic states. This storm was named after the collapse of the Knickerbocker Theater in Washington, D.C. shortly after 9 p.m. on January 28. The movie theater's flat roof collapsed under the weight of 28 inches of wet snow, bringing down the balcony and a portion of the brick wall and killing 98 people, including a Congressman. An arctic air mass had been in place across the Northeast for several days before the storm, and Washington had been below freezing since the afternoon of January 23. The storm formed over Florida on January 26 and took three days to move up the Eastern Seaboard. Snow reached Washington and Philadelphia by noon on January 28 and continued into the morning of January 29. Winds gusting up to 50 mph created blizzard conditions, and heavy drifting blocked roads for days. Railroad lines between Philadelphia and Washington were covered by at least 36 inches of snow, with drifts as high as 16 feet. Figure above presents data from the 20th Century Reanalysis Project's three- dimensional reanalysis of conditions at 7p.m. on January 28, 1922. With data like this available for the entire 20th century, climate researchers hope to improve their models so that they can more confidently predict regional weather trends for the future.
* Source: SCIDAC Review, Spring, 2008 http://www.scidacreview.org/0801/pdf/climate.pdf.
Analysis and Plotting Tools
Please use these pages below to plot the 20th Century Reanalysis Version 1 data.
Clicking on graphics will show full sized images of the example plots. Clicking on the plotting tool descriptions, 1) Monthly Composites, 2) Daily Average Composites, and 3) Monthly/Seasonal Google Earth Interface will show respective plotting tool pages. You can also use the PSD Search and Plot page. This is less flexible but can access all the data. Search for dataset(s) 'NOAA-CIRES 20th Century...'.
 (D-Day month) |  |  |
| Monthly Composites | Daily Average Composites | Monthly/Seasonal Google Earth Interface |
Version 2
 (D-Day month) |
| 6-Hourly Composites |
Dataset Information:
Data and more information can be found at the
- NOAA/ESRL PSD 20th Century Reanalysis version 1 data documentation page.
- NCAR 20th Century Reanalysis version 1 data documentation page.
- NOAA/ESRL PSD 20th Century Reanalysis version 2 data documentation page.
- NCAR 20th Century Reanalysis version 2 data documentation page.
Useful dataset analysis plots can be found here
 example is SLP and 500z, Jan 1 12z 1900 |  Expected and Actual Error of the 20th Century Reanalysis First Guess v.2 (1891-2006)[ps] |
Acknowledgment:
The Twentieth Century Reanalysis Project used resources of the National Energy Research Scientific Computing Center and of the National Center for Computational Sciences at 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.
Papers using the Twentieth Century Reanalysis Project dataset 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 Innovative and Novel Computational Impact on Theory and Experiment (DOE INCITE) program, and Office of Biological and Environmental Research (BER), and by the National Oceanic and Atmospheric Administration Climate Program Office."
Related Data Sources
- GCOS Surface Pressure Working Group
- National Climatic Data Center
- International Best Track Archive for Climate Stewardship
- NCEP_NCAR Reanalysis Project
- National Centers for Environmental Prediction
- National Center for Atmospheric Research
- Atmospheric Circulation Reconstructions over the Earth.
Other Useful Webpages:
- PSD Monthly Climate Indices
Plot, analyze and obtain various ocean and atmospheric indices including the the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO) the SOI and many others.