WG3: Verification and Validation

WG Leader (Dr Gil Compo, U. of Colorado CIRES Climate Diagnostics Center and NOAA Earth System Research Laboratory, United States - compo@colorado.edu)

Terms of reference:

Testing against independent data sources;

Best practice;

Inter-comparisons between reanalyses and reconstructions;

Feedback on the 20th Century Reanalysis Project (eventually moving to SIRCA)

Members:  Xiaolan Wang (Xiaolan.Wang@ec.gc.ca); Russ Vose (Russell.Vose@noaa.gov); Cathy Smith (Cathy.Smith@noaa.gov); Irina Rudeva (rudeva@sail.msk.ru) Thomas Reichler (thomas.reichler @utah.edu); Diodata Nazzareno (nazdiod@tin.it); Juerg Luterbacher (juerg.luterbacher@geogr.uni-giessen.de);Nick Klingaman (n.p.klingaman@reading.ac.uk); Julie Jones (julie.jones@sheffield.ac.uk); Edward Hanna (E.Hanna@sheffield.ac.uk); Sergey Gulev (gul@sail.msk.ru); Ben Giese  (b-giese@tamu.edu); John Fasullo (fasullo@ucar.edu); Helen Fairweather (Helen.Fairweather@climatechange.qld.gov.au); Paul Della-Marta  (Paul.Della-Marta@partnerre.com); Jim Carton  (carton@atmos.umd.edu); Antonio S. Cofiño (antonio.cofino@unican.es); Stefan Brönnimann (stefan.broennimann@giub.unibe.ch); Michael Bosilovich (michael.g.bosilovich@nasa.gov); Michela Biasutti  (mbiasutti@gmail.com); Phil Arkin  (parkin@essic.umd.edu); Rob Allan (rob.allan@metoffice.gov.uk)

The 20th Century Reanalysis Project

The 20th Century Reanalysis Project is an effort to produce a reanalysis dataset spanning the entire twentieth century (1871-present), assimilating only surface observations and reports of synoptic pressure, monthly sea surface temperature and sea-ice distributions using an Ensemble Kalman Filter data assimilation system. The SST and sea-ice data are courtesy of the UK Met Office Hadley Centre from their HadISST dataset. The pressure observations dataset, the International Surface Pressure Databank (ISPD), has been assembled through international cooperation under the auspices of the international ACRE initiative (http://www.met-acre.org), and working groups of GCOS and WCRP.


Global four-times-daily atmospheric and surface analysis fields spanning 1871 to 2010 from the 20th Century Reanalysis Project Version 2 dataset are now available at (http://www.esrl.noaa.gov/psd/data/gridded/data.20thC_ReanV2.html) in netCDF format, courtesy of the NOAA Earth System Research Laboratory, Physical Sciences Division (PSD), and University of Colorado CIRES/Climate Diagnostics Center (CDC), and are also available via our partners at the National Center for Atmospheric Research (http://dss.ucar.edu/datasets/ds131.1) in GRIB format, and the U.S. Dept. of Energy National Energy Research Scientific Computing Center (http://portal.nersc.gov) for every member in netCDF4 format, and will soon be available via our partners at NOAA’s National Climatic Data Center (NCDC) through the NOAA Operational Model Archive and Distribution System (NOMADS) (http://nomads.ncdc.noaa.gov) and the NCDC Data Archive in the near future.


Plotting tools for four-times-times daily, daily, and monthly means are now available courtesy of N. Wilde and the PSD IT group, Cathy Smith and Don Hooper of NOAA/ESRL/PSD and CU/CIRES/CDC at (http://www.esrl.noaa.gov/psd/data/20thC_Rean/).


Pre-generated synoptic maps showing the ensemble mean analysis and analysis uncertainty of Sea Level Pressure and 500 hPa height over the Northern and Southern Hemispheres and for Sea Level Pressure and 850 hPa zonal wind in the tropics are available at (http://www.esrl.noaa.gov/psd/data/20thC_Rean/hem_images.html).


The Version 2 dataset spans 1871-2010.


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.C. 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, S.J. Worley, 2011: The Twentieth Century Reanalysis Project. Quart. J. Roy. Meteor. Soc., 137, 1-28. DOI: 10.1002/qj.776..


The Project home page can be found at (http://www.esrl.noaa.gov/psd/data/20thC_Rean/) .


Future planned extensions of these ACRE-facilitated reanalyses aim to ultimately cover the last 200+ years:


Sparse Input Reanalysis for Climate Applications (SIRCA): 1850-2013 [Autumn 2014]


Ocean Atmosphere Reanalysis for Climate Applications (OARCA): 1800-2018 [Autumn 2018]

Reanalysis Intercomparison and Observations (Reanalyses.org)

The working group is promoting evaluation of reanalyses and observations through the interactive website reanalyses.org (Reanalysis Intercomparison and Observations). To participate, request a login.

Surface Data Sources


Reanalysis Products




Reanalyses.org WWW page



The Twentieth Century Reanalysis Project used resources of the National Energy Research Scientific Computing Center and of the Oak Ridge Leadership Computing Facility 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."

20CRv2 access via the British Atmospheric Data Centre