Reanalysis and Observational datasets and variables available from page

Reanalyses datasets include 6 pressure level variables (heights, winds, omega, air temperature, specific humidity and relative humidity (if a dataset has that variable).Five single level variables are also available including 2m air temperature, 10m winds, SLP and precipitation rate. In addition 2 observational datasets are available, the CRU_TS 3.10 and the U of Delaware 3.01 air temperature and precipitation.Different datasets have different analyses levels available so you may need to consider that when choosing differences. The dataset are at different resolutions. Differences are computed by interpolating the lower resolution dataset of the two being compared to the resolution of the higher res and subtracting. Anomalies are based on the climatology from each reanalyses dataset separately. Units have been changed to be consistent so the datasets can be compared.

For more information and discussion of various atmospheric and oceanic reanalyses, see the "Reanalysis Intercomparison and Observations Wiki" at For references/citations please go to the wiki page for a current list.

Dataset Availability. More data may be available at the source.

DatasetStart DataEnd DateClimo Available
NCEP/NCAR Reanalysis Jan 1948near present1981-2010
NCEP/DOE Reanalysis IIJan 1979Jun 20121981-2010
20CRJan 1871Dec 20101981-2010
NCEP CFSR (Not Available)Jan 1979Dec 20111981-2010
MERRAJan 1979Dec 20111981-2010
ERA-InterimJan 1979Dec 20111981-2010
U of Delaware 3.01Jan 1900Dec 20101981-2010
CRU_TS 3.10Jan 1901Dec 20101981-2009
GHCN-CAMSJan 1948near present1981-2010
  • NCEP/NCAR Reanalysis I 1948-present (NCEP R1 home page)

    This reanalysis was the first of its kind for NOAA. NCEP used the same climate model that was initialized with a wide variety of weather observations: ships, planes, RAOBS, station data, satellite observations and many more. By using the same model, scientists can examine climate/weather statistics and dynamic processes without the complication that model changes can cause. The dataset is kept current using near real-time observations.
  • NCEP/DOE Reanalysis II (1979-2011)

    NCEP produced a second version of their first reanalysis starting from the beginning of the major satellite era. More observations were added, assimilation errors were corrected and a better version of the model was used.
  • 20th Century Reanalysis (V2) 1871-2010 (20CR Home page)

    The 20th Century Reanalysis version 2 dataset contains global weather conditions and their uncertainty in six hour intervals from the year 1871 to 2010. Surface and sea level pressure observations are combined with a short-term forecast from an ensemble of integrations of an NCEP numerical weather prediction model using the recently developed Ensemble Kalman Filter technique to produce an estimate of the complete state of the atmosphere, and the uncertainty in that estimate. Additional observations and a newer version of the NCEP model that includes time-varying CO2 concentrations, solar variability, and volcanic aerosols are used in version 2. The long time range of this dataset allows scientists to examine better long time scale climate processes such as the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation as well as looking at the dynamics of historical climate and weather events. Verification tests have shown that using only pressure creates reasonable atmospheric fields up to the tropopause. Additional tests suggest some correspondence with observed variations in the lower stratosphere.
  • NCEP Climate Forecast System Reanalysis (CFSR): 1979-Dec 2009 (CFSR Home page.)

    The National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) was completed over the 31-year period of 1979 to 2009 in January 2010. The CFSR was designed and executed as a global, high resolution, coupled atmosphere-ocean-land surface-sea ice system to provide the best estimate of the state of these coupled domains over this period. The current CFSR will be extended as an operational, real time product into the future.
  • NASA Modern Era Reanalysis for Research and Applications (MERRA): 1979-present (MERRA Home page)

    MERRA is a NASA reanalysis for the satellite era using a major new version of the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5) produced by the NASA GSFC Global Modeling and Assimilation Office (GMAO). The Project focuses on historical analyses of the hydrological cycle on a broad range of weather and climate time scales and places the NASA EOS suite of observations in a climate context.
  • ERA-Interim: 1979-present (ERA-Interim Home page)

    ERA-Interim was originally planned as an 'interim' reanalysis in preparation for the next-generation extended reanalysis to replace ERA-40. It uses a December 2006 version of the ECMWF Integrated Forecast Model (IFS Cy31r2). It originally covered dates from 1 Jan 1989 but an additional decade, from 1 January 1979, was added later. ERA-Interim is being continued in real time. The spectral resolution is T255 (about 80 km) and there are 60 vertical levels, with the model top at 0.1 hPa (about 64 km). The data assimilation is based on a 12-hourly four-dimensional variational analysis (4D-Var) with adaptive estimation of biases in satellite radiance data (VarBC). With some exceptions, ERA-Interim uses input observations prepared for ERA-40 until 2002, and data from ECMWF's operational archive thereafter. An pen-access journal article describing the ERA-Interim reanalysis is now available from the Quarterly Journal of the Royal Meteorological Society and should be used as the citation.
  • U of Delaware surface temperature and precipitation (V3.01)

    See PSD's documentation and links
  • CRU_TS 3.10

    See BADC's Webpage

    See PSD's documentation for GPCP V2 monthly data
  • NOAA's Reconstructed Precipitation 1.0x1.0 land only

    See PSD's documentation for NOAA's Reconstructed Precipitation 1.0x1.0 land only
  • CPC Monthly Global Surface Air Temperature Data Set (GHCN-CAMS) surface temperature

    Dataset is a high resolution (0.5), globally gridded monthly air temperature dataset. See Documentation link from the IRI.. References are
    • Yun Fan and Huug van den Dool, 2008: A global monthly land surface air temperature analysis for 1948-present. J. Geophys. Res. DOI:10.1029/2007JD008470
    • Yun Fan and Huug van den Dool, 2004: Climate Prediction Center global monthly soil moisture data set at 0.5° resolution for 1948 to present. J. Geophys. Res., VOL. 109, D10102, doi:10.1029/2003JD004345.