The Twentieth Century Reanalysis (20CR) provides a comprehensive global atmospheric circulation data set spanning 1850-2014. Its chief motivation is to provide an observational validation data set, with quantified uncertainties, for assessing climate model simulations of the 20th century, with emphasis on the statistics of daily weather. The analyses are generated by assimilating only surface pressures and using monthly SST and sea ice distributions as boundary conditions within a 'deterministic' Ensemble Kalman Filter (EKF). A unique feature of the 20CR is that estimates of uncertainty are derived using a 56 member ensemble. Overall, the quality is approximately that of current three-day NWP forecasts.
20th Century Reanalysis Version v2c uses the same model as version 2 with new sea ice boundary conditions from the COBE-SST2 (Hirahara et al. 2014), new pentad Simple Ocean Data Assimilation with sparse input (SODAsi.2) sea surface temperature fields, and additional observations from ISPD version 3.2.9.
As of 2020, NOAA has released 20CRv3, which covers the period 1806-2015. More information about 20CRv3 will be added to the Climate Data Guide soon.
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Air temperature at the lowest model level, sigma.995, from the 20CRV2 ensemble mean. Averaged for 1951-1980. Credit: Climate Data Guide. |
National Center for Atmospheric Research Staff (Eds). Last modified 15 Jan 2021. "The Climate Data Guide: NOAA 20th-Century Reanalysis, Version 2 and 2c." Retrieved from https://climatedataguide.ucar.edu/climate-data/noaa-20th-century-reanalysis-version-2-and-2c.
Funding: NSF | National Science Foundation
Based at: NCAR | National Center for Atmospheric Research
A Project of: Climate Analysis Section in Climate and Global Dynamics Laboratory
Created by: Climate Data Guide PIs and Staff
