WRIT Monthly Time-series Plotting Page: Reanalysis and Observational Datasets and Variables

The different datasets have different analyses levels so you may need to consider that when choosing differences. The dataset are at different resolutions. Differences are computed by interpolating the lower res dataset of the two being compared to the resolution of the higher res and subtracting. Anomalies are based on the climo from each reanalyses dataset separately. Units have been changed so the datasets can be compared. More recent data may be available at the source.

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


Reanalyses Datasets
DatasetStart Date1End Date1Climo AvailableClimate Data Guide (NCAR) or other
NCEP/NCAR Reanalysis Jan 1948Jan 2020 1981-2010Guide
NCEP/DOE Reanalysis IIJan 19791981-2010Guide
20CRV2cJan 1851Dec 20141981-2012Guide
20CRv3Jan 1836Dec 20151981-2012
NCEP CFSRJan 1979Jan 2020 1981-2010Guide
MERRA 2Jan 1980Jan 2020 1981-2010NASA MERRA2 Page
ERA-InterimJan 1979Aug 2019 1981-2010Guide
JRA-55Jan 1958Jan 2020 1981-2010Guide
JRA-55 ScreenJan 1958Jan 2020 1981-2010Guide
CERA-20CJan 1901Dec 20101981-2010EC page
MERRAJan 1979Jan 20151981-2010Guide
20CRJan 1871Dec 20121981-2012Guide
  • 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, V2c (1851-2014), and V3 (1836-2015)(20CR Home page)

    The 20th Century Reanalysis V2 and V2c dataset contains global weather conditions and their uncertainty in six hour intervals from the year 1856 to 2014. V3 has 3 hourly data from 1836-2015. 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.
  • NASA Modern Era Reanalysis for Research and Applications (MERRA): 1979-2015 (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.
  • NASA Modern Era Reanalysis for Research and Applications (MERRA-2): 1980-present (MERRA Home page)

    The Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) provides data beginning in 1980. It was introduced to replace the original MERRA dataset because of the advances made in the assimilation system that enable assimilation of modern hyperspectral radiance and microwave observations, along with GPS-Radio Occultation datasets. It also uses NASA ozone observations after 2005. Additional advances in both the GEOS-5 model and the GSI assimilation system are included in MERRA-2. Spatial resolution remains about the same (about 50 km in the latitudinal direction) as in MERRA. Along with the enhancements in the meteorological assimilation, MERRA-2 takes some significant steps towards GMAO’s target of an Earth System reanalysis. MERRA-2 is the first long-term global reanalysis to assimilate space-based observations of aerosols and represent their interactions with other physical processes in the climate system. MERRA-2 includes a representation of ice sheets over (say) Greenland and Antarctica.
  • 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.
  • ERA-20C: 1900-2010 (ERA-20C Home page)

    ERA-20C is ECMWF's first atmospheric reanalysis of the 20th century, from 1900-2010. It assimilates observations of surface pressure and surface marine winds only. It is an outcome of the ERA-CLIM project.
  • JRA-55: 1958-present (JRA-55 Home page)

    JMA carried out the second reanalysis project (known as the Japanese 55-year Reanalysis, or JRA-55) using a more sophisticated DA system based on the operational system as of December 2009, and newly prepared dataset of past observations. The analysis period covers the 55 years from 1958, when regular radiosonde observation began on a global basis. Many of the deficiencies of JRA-25 are alleviated in JRA-55 because the DA system used for the project featured a variety of improvements introduced after JRA-25. As a result, the JRA-55 project produced a high-quality homogeneous climate dataset covering the last half century. References
    1. Ebita, A., S. Kobayashi, Y. Ota, M. Moriya, R. Kumabe, K. Onogi, Y. Harada, S. Yasui, K. Miyaoka, K. Takahashi, H. Kamahori, C. Kobayashi, H. Endo, M. Soma, Y. Oikawa, and T. Ishimizu, 2011: The Japanese 55-year Reanalysis "JRA-55": an interim report, SOLA, 7, 149-152. (This article is an interim report of JRA-55 as of 2011. A comprehensive report of JRA-55 was submitted to J. Meteor. Soc. Japan (as of May 2014).)
    2. Onogi, K., J. Tsutsui, H. Koide, M. Sakamoto, S. Kobayashi, H. Hatsushika, T. Matsumoto, N. Yamazaki, H. Kamahori, K. Takahashi, S. Kadokura, K. Wada, K. Kato, R. Oyama, T. Ose, N. Mannoji and R. Taira (2007) : The JRA-25 Reanalysis. J. Meteor. Soc. Japan, 85, 369-432.
  • NASA GPCP V3.2


    NOAA Extended Reconstructed Sea Surface Temperature (ERSST) is a gridded 5x5 resolution SST dataset extending back into the 19th century.

    NOAA Extended Reconstructed Sea Surface Temperature (ERSST) is a gridded 5x5 resolution SST dataset extending back into the 19th century.

    NOAA Extended Reconstructed Sea Surface Temperature (ERSST) is a gridded 5x5 resolution SST dataset extending back into the 19th century.
  • WASWind

    Wave and Anemometer-based Sea Surface Wind (WASWind) from the U of Hawaii. It a gridded a sea surface wind dataset from ship observations of wind speed and wind wave height archived in the International Comprehensive Ocean-Atmosphere Data Set (ICOADS).
  • HadSLP2

    Hadley Centre Sea Level Pressure dataset (HadSLP2) is a gridded 5x5 resolution SLP dataset extending back into the 19th century. After 2004, values are filled in using the NCEP/NCAR R1 dataset.
WRIT is supported in part by NOAA/ESRL Physical Sciences Division, the NOAA Climate Program Office, and the US Department of Energy's Office of Science (BER). WRIT contributes to the Atmospheric Circulation Reconstructions over the Earth (ACRE) Initiative.