NOAA/ESRL 20th Century Reanalysis – V2 / V2c

Pressure levels: 6-hourly

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 international effort led by Physical Science Division and the University of Colorado CIRES Climate Diagnostics Center to produce a comprehensive global atmospheric circulation dataset spanning the twentieth century, assimilating only surface pressure reports and using observed monthly sea-surface temperature and sea-ice distributions as boundary conditions. The observations have been assembled through international cooperation under the auspices of the Atmospheric Circulation Reconstructions over the Earth initiative (ACRE), and working groups of GCOS and WCRP. It is chiefly motivated by a need to provide an observational dataset with quantified uncertainties for validations of climate model simulations of the twentieth century on all time-scales, with emphasis on the statistics of daily weather. The Project uses an Ensemble Kalman Filter data assimilation method with background ‘first guess’ fields supplied by an ensemble of forecasts from a global numerical weather prediction model. This directly yields a global analysis every 6 hours as the most likely state of the atmosphere, and also an uncertainty estimate of that analysis. Intercomparisons with independent radiosonde data indicate that the reanalyses are generally of high quality. The quality in the extratropical Northern Hemisphere throughout the century is similar to that of current three-day operational NWP forecasts. Intercomparisons over the second half-century of these surface-based reanalyses with other reanalyses that also make use of upper-air and satellite data are equally encouraging.

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Variables
Air Temperature (degK)
Geopotential Heights (m)
Omega (Pascal/s)
Relative Humidity (%)
Specific Humidity (kg/kg)
U-wind (m/s)
V-wind (m/s)
ZonalGlobal by 2.0 deg
MeridionalGlobal by 2.0 deg
VerticalPressure Levels (hpa): 1000 950 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 70 50 30 20 10  
Temporal V2: Jan 1, 1871 to Dec 31, 2012 by 6 hours
V2c: Jan 1, 1851 to Dec 31, 2014 by 6 hours
Static?no
Volume1.1GB per variable per year
Serverpublic:
Sourcehttp://www.esrl.noaa.gov/psd/data/gridded/data.20thC_ReanV2.html
http://www.esrl.noaa.gov/psd/data/gridded/data.20thC_ReanV2c.html
Acquired Mar 12, 2012 (Updated Nov 2016)
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