Japanese 25-year ReAnalysis : JRA-25

December, 2008 updated



The Japan Meteorological Agency (JMA) conducted the Japanese 25-year ReAnalysis (JRA-25) in collaboration with the Central Research Institute of Electric Power Industry (CRIEPI) and produced high quality meteorological datasets for seasonal prediction models and climate research use.


JRA-25 Overview
  • Joint research project between JMA and CRIEPI
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  • Period reanalyzed: from Jan. 1979 to Dec. 2004 (26 years)
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  • Global model resolution : T106L40 (model top: 0.4hPa)
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  • Data assimilation : 3D-Var
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  • Numerical assimilation system : JMA's operational system of April 2004.

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    In addition, SSM/I PW, and TOVS radiance level 1c (SSU) and 1d (HIRS, MSU) were assimilated.
  • JRA-25 was the first reanalysis to use the observational data outlined below
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    Wind profile retrievals surrounding tropical cyclones (TCR), SSM/I snow coverage, digitized Chinese snow depth data, reprocessed GMS-AMV
  • JRA-25 original boundary/forcing data
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    Daily COBE SST and sea ice (Ishii 2005, IJC), daily 3D-ozone profile

    Observation availability in JRA-25


    Forecast Score for JRA-25 ( Z500 FT=24 RMSE )


    Application of JRA-25 for operation and research


    Comparison between JRA-25 and other reanalyses
    Name Organization Period Resolution Assimilation Memorandum
    JRA-25 JMA/CRIEPI 1979-2004 T106L40 3DVAR continues as JCDAS since 2005
    ERA-15 ECMWF 1979-1993 T106 L31 OI completed in 1996
    ERA-40 ECMWF 1957.9-2002.8 TL159 L60 3DVAR completed in 2003
    NCEP-NCAR(Reanalysis-1) NCEP-NCAR 1948-present T62 L28 3DVAR continues as CDAS
    NCEP-DOE AMIP-II(Reanalysis-2) NCEP-DOE 1979-present T62 L28 3DVAR continues as CDAS
    GEOS1 NASA/DAO 1980-1996 2x2.5 L20 OI + IAU completed up to 1996

    T: Triangular truncation, TL: Triangular with Linear reduced Gaussian grid, L: Vertical layers.

    T106 and TL159 are comparable to a lat-lon grid with intervals of about 110km, while T62 is comparable to the same with intervals of about 180km.


    Definition of vertical levels for the model used in JRA-25 and JCDAS


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