WRIT Monthly Seasonal Correlation Page: Reanalysis and Observational Datasets and Variables

Reanalyses and observational datasets available on the page are listed in the tables that follow. For more information and discussion of various atmospheric and oceanic reanalyses, see the "Reanalysis Intercomparison and Observations Wiki" (http://reanalysis.org). This wiki includes references/citations and a detailed reanalyses comparison table. Different reanalysis datasets have different pressure levels output so you may need to consider that when differencing variables. Datasets are produced at differing spatial resolutions. Plot differences are computed by interpolating the lower resolution dataset of the two being compared to the resolution of the higher resolution and subtracting. Anomalies are based on the climatology from each reanalyses dataset separately. Variable units have been changed to be consistent so the datasets can easily be compared. More recent data may be available at the source.


Reanalyses Datasets
DatasetVariablesStart Date1End Date1Climo AvailableClimate Data Guide (NCAR) or other
NCEP/NCAR Reanalysis T,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1948Mar 2024 1981-2010Guide
NCEP/DOE Reanalysis IIT,Z,U,V,O,R: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1979Mar 2024 1981-2010Guide
20CRv3T,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1836Dec 20151981-2010
20CRV2cT,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1851Dec 20141981-2012Guide
NCEP CFSRT,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1979Mar 2024 1981-2010Guide
MERRA 2T,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1980Feb 2024 1981-2010NASA MERRA2 Page
ERA5T,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1948Mar 2024 1991-2020Guide
ERA-InterimT,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1979Aug 2019 1981-2010Guide
JRA-55T,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1958Jan 2024 1981-2010Guide
JRA-55 ScreenTs,Us,Vs,SsJan 1958Jan 2024 1981-2010Guide
CERA-20CTs,Us,Vs,SsJan 1901Dec 20101981-2010EC page
MERRAT,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1979Jan 20151981-2010Guide
20CRT,Z,U,V,O,R,S: Ts,Us,Vs,Ss,SLP,P,Pw,E,Sk,IJan 1871Dec 20121981-2010Guide

Observational Datasets
DatasetVariablesStart Date1End Date1Climo Available at PSLClimate Data Guide (NCAR) or other
Berkeley Temperature (land/ocean)2m temperatureJan 1850near present1981-2010Guide
U of Delaware 5.012m temperature, precipitationJan 1900Dec 20171981-2010Guide
CRU_TS 3.252m temperatureJan 1901Dec 20161981-2010CRU Webpage
COBE SSTJan 1891near present1981-2010Guide
COBE-2 SSTSSTJan 1850Dec 20161981-2010JMA Webpage
GHCN-CAMS2m temperatureJan 1948near present1981-2010PSL GHCN-CAMS Doc
HadSLP2SLPJan 1871near present (full is 1850)1981-2010PSL HadSLP2 doc
GPCP V2.3precipitationJan 1979near present1981-2010Guide
CMAP (STD)precipitationJan 1979near present1981-2010Guide
Dai PDSIPalmer Drought Severity Index (PDSI)Jan 187020141981-2010NCAR Doc
Gridded SIBTSea-ice concentrationJan 1851Dec 20131981-2010NSIDC link
HadISST 1.1 SST,IceJan 1870near present1981-2010Guide
HadISST 2.2 IceJan 1870near present1981-2010Met Office
HadNMAT2 2m temperature (night-time)Jan 188020101961-1990Met Center HadNMAT2 page
JMA Temperature Anomalies2m temperature (night-time)Jan 189120161981-2010JMA Webpage
NOAA ERSST V3v,V4, and V5SSTJan 1870near present1981-2010V3b Guide,V4 Guide
NOAA Global Temperature Anomalies2m temperatureJan 1880near present1981-2010NCEI doc
NOAA Reconstructed Land PrecipPrecipitationJan 1948near present1981-2010Guide
WASWinds10m zonal, meridional windsJan 1950Dec 20111981-2010Guide

Reanalysis Variables

Pressure Level
geopotential height (Z)
zonal wind (U)
meridional wind (V)
omega (O)
air temperature (T)
specific humidity (S)
relative humidity (R)
Single Level
2m air temperature (Ts)
precipitation rate (P)
10m zonal wind (Us)
10m meridional wind (Vs)
precipitable water (Pw)
evaporation rate (E)
SST/Skin Temperature (Sk)
Users should enter "2m air temperature" for temperature and precipitation rate for precipitation in observed datasets.

1 Start and end dates reflect data on the WRIT pages and may not reflect what is available at the source.


  • 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 (1979-2017)

    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 1871-2012, V2c 1851-2014, and V3 1836-2015 (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 2012 (V2) and 1851-2011(V2c). It has 3 hourly values for V3 (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.
  • NCEP Climate Forecast System Reanalysis (CFSR): 1979-Dec 2013 (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 is extended as an operational, real time product into the future past 2009.
  • 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.
  • 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.


  • 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..
  • COBE

    JMA SST analysis monitoring dataset updated in real-time
  • COBE-2 SST

    JMA SST analysis dataset. It is analyzed using the same method for the entire time period and is not up-to-date. Occasionally the analysis is rerun.
  • CRU_TS 3.25

  • NASA GPCP V2.3

  • CMAP Standard (NOAA)

  • NOAA's Reconstructed Precipitation 1.0x1.0 land only

  • Gridded Monthly Sea Ice Extent and Concentration, 1850 Onwards

    See NSIDC's documentation on the dataset. For citation, use Walsh, J. E., W. L. Chapman, and F. Fetterer. 2015. Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5833PZ5. [Date Accessed].
  • HadISST 1.1 SST

  • HadISST 2.2 Ice

  • HadNMAT2 Night Marine Air Temperature

  • 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.
  • NOAA ERSST: V3b,V4, and V5

    NOAA Extended Reconstructed Sea Surface Temperature (ERSST V5) is a gridded 5x5 resolution SST dataset extending back into the 19th century. The older V4 and V3b are also still available.
  • JMA Temperature

    Global temperature anomalies from the JMA.
  • 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).
  • U of Delaware surface temperature and precipitation (V5.01)

  • WRIT is supported in part by NOAA/ESRL Physical Sciences Laboratory, 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.