Japanese 25-year Reanalysis Project

The Japanese 25-year Reanalysis (JRA-25) represents the first long-term global atmospheric reanalysis undertaken in Asia. Covering the period 1979-2004, it was completed using the Japan Meteorological Agency (JMA) numerical assimilation and forecast system and specially collected and prepared observational and satellite data from many sources including the European Center for Medium-Range Weather Forecasts (ECMWF), the National Climatic Data Center (NCDC), and the Meteorological Research Institute (MRI) of JMA. A primary goal of JRA-25 is to provide a consistent and high-quality reanalysis dataset for climate research, monitoring, and operational forecasts, especially by improving the coverage and quality of analysis in the Asian region.

In JRA-25, three-dimensional variational (3D-Var) data assimilation and a global spectral model were employed to produce 6-hourly atmospheric analysis and forecast cycles. The global spectral model was based on a 320 by 160 (~1.125 degree) Gaussian grid with T106 truncation. Vertical discretization employed a hybrid sigma-pressure coordinate utilizing 40 levels where 0.4 hPa represents the model top level. A predictive mass-flux Arakawa-Schubert scheme was utilized for cumulus parameterization, and Simple Biosphere (SiB) parameterizations for land-surface processes. Assimilated variables include temperature, relative humidity, and surface pressure from conventional observations, and also winds retrieved from geostationary satellites, radiative brightness temperature from TIROS Operational Vertical Sounder (TOVS), and precipitable water from Special Sensor Microwave/Imager (SSM/I). Variables not directly assimilated include daily sea surface temperature (SST) and sea ice based on Centennial in-situ Observation-Based Estimates (COBE), and ozone profiles based on chemical transport models constrained by observations from Total Ozone Mapping Spectrometer (TOMS).

The JRA-25 shows marked improvement over previous reanalyses in several notable areas, especially predicted (both 6-hourly and long term) precipitation, with more realistic variability and fewer spurious trends due to contamination of satellite data by volcanic eruptions. JRA-25 is also the first reanalysis to assimilate wind profiles around tropical cyclones deduced from best-track data, resulting in improved tropical cyclone analysis in a global context. In addition, low-level (stratus) cloud decks along the western subtropical coasts of continents are also better simulated, improving radiation budgets in these regions.

In 2006, JMA started real-time operation of the JMA Climate Data Assimilation System (JCDAS). JCDAS employs the same system as JRA-25 and the data assimilation cycle is extended to the present time. JRA-25 and JCDAS products will enable users to conduct climate diagnostics with a long-term, and current, homogeneous reanalysis dataset. The JMA has also engaged in ongoing cooperation with ECMWF (European Center for Medium-Range Weather Forecasts) on reanalysis, including the ECMWF CDAS (ECDAS), more commonly known as ERA-Interim.

To Access Resource:

Questions? Email Resource Support Contact:

  • Dave Stepaniak
    UCAR/NCAR - Research Data Archive

Temporal Range

  • Begin:  1979-01-01T00:00:00Z
    End:  2014-02-01T18:00:00Z


Resource Type dataset
Temporal Range Begin 1979-01-01T00:00:00Z
Temporal Range End 2014-02-01T18:00:00Z
Temporal Resolution N/A
Bounding Box North Lat N/A
Bounding Box South Lat N/A
Bounding Box West Long N/A
Bounding Box East Long N/A
Spatial Representation N/A
Spatial Resolution N/A
Related Links

Related Resource #1 : Japanese 25-year ReAnalysis (JRA-25) and JMA Climate Data Assimilation System (JCDAS)

Related Resource #2 : Description of the JRA-25 at the NCAR Climate Data Guide

Related Resource #3 : Related Resouces: JRA-25 Quality Issues

Additional Information N/A
Resource Format WMO_GRIB1 (Binary)
Standardized Resource Format GRIB
Asset Size 19107321 MB
Legal Constraints

When accessing the JRA data, you agree to the following Terms and Conditions:

(1) The datasets are to be used only for research purposes.

(2) Users cannot edit the JRA-25 datasets and then claim they are official products.

(3) Users are explicitly not permitted to redistribute the JRA-25 to third parties, including derived products such as filtered time series, fields not originally part of JRA-25, etc.

(4) JMA does not accept liability for any resulting damage caused by the use of the JRA-25 datasets.

(5) Users are obligated to duly acknowledge the JRA-25 in all scientific or technical papers, publications, press releases or other communications regarding the datasets.

(6) Users are obligated to provide the JMA with a copy of their scientific or technical papers, publications, press releases or other communications regarding the datasets.

The recommended acknowledgement statement for publication is, "The datasets used for this study are provided from the cooperative research project of the JRA-25 long-term reanalysis by the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry (CRIEPI)."

Access Constraints Registration on the RDA web site is a requirement for access to the data.
Software Implementation Language N/A

Resource Support Name Dave Stepaniak
Resource Support Email davestep@ucar.edu
Resource Support Organization UCAR/NCAR - Research Data Archive
Distributor NCAR Research Data Archive
Metadata Contact Name N/A
Metadata Contact Email rdahelp@ucar.edu
Metadata Contact Organization NCAR Research Data Archive

Author Japan Meteorological Agency, Japan
Central Research Institute of Electric Power Industry, Japan
Publisher Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory
Publication Date 2007-05-30
Digital Object Identifier (DOI) https://doi.org/10.5065/FV8A-M862
Alternate Identifier ds625.0
Resource Version N/A
Topic Category climatologyMeteorologyAtmosphere
Progress onGoing
Metadata Date 2024-02-28T21:05:03-07:00
Metadata Record Identifier edu.ucar.rda::ds625.0
Metadata Language eng; USA
Suggested Citation Japan Meteorological Agency, Japan, Central Research Institute of Electric Power Industry, Japan. (2007). Japanese 25-year Reanalysis Project. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/FV8A-M862. Accessed 20 June 2024.

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