JRA-55: Japanese 55-year Reanalysis, Monthly Means and Variances

| DOI: 10.5065/D60G3H5B

The Japan Meteorological Agency (JMA) conducted JRA-55, the second Japanese global atmospheric reanalysis project. It covers 55 years, extending back to 1958, coinciding with the establishment of the global radiosonde observing system. Compared to its predecessor, JRA-25, JRA-55 is based on a new data assimilation and prediction system (DA) that improves many deficiencies found in the first Japanese reanalysis. These improvements have come about by implementing higher spatial resolution (TL319L60), a new radiation scheme, four-dimensional variational data assimilation (4D-Var) with Variational Bias Correction (VarBC) for satellite radiances, and introduction of greenhouse gases with time varying concentrations. The entire JRA-55 production was completed in 2013, and thereafter will be continued on a real time basis.

Specific early results of quality assessment of JRA-55 indicate that a large temperature bias in the lower stratosphere has been significantly reduced compared to JRA-25 through a combination of the new radiation scheme and application of VarBC (which also reduces unrealistic temperature variations). In addition, a dry land surface anomaly in the Amazon basin has been mitigated, and overall forecast scores are much improved over JRA-25.

Most of the observational data employed in JRA-55 are those used in JRA-25. Additionally, newly reprocessed METEOSAT and GMS data were supplied by EUMETSAT and MSC/JMA respectively. Snow depth data over the United States, Russia and Mongolia were supplied by UCAR, RIHMI and IMH respectively.

The Data Support Section (DSS) at NCAR has processed the 1.25 degree version of JRA-55 with the RDA (Research Data Archive) archiving and metadata system. The model resolution data has also been acquired, archived and processed as well, including transformation of the TL319L60 grid to a regular latitude-longitude Gaussian grid (320 latitudes by 640 longitudes, nominally 0.5625 degree). All RDA JRA-55 data is available for internet download, including complete subsetting and data format conversion services.

Temporal Range:
1958-01-01 00:00 +0000 to 2024-01-01 00:00 +0000 (Entire dataset) Period details by dataset product
Usage Restrictions:

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

a. Conditions of use

  • Individual users must register their name, affiliation and email address with NCAR before access to datasets will be permitted.
  • The source of the datasets should be duly acknowledged in scientific and technical papers, publications, press releases and other communications regarding the datasets. Example: The dataset used for this study is from the Japanese 55-year Reanalysis (JRA-55) project carried out by the Japan Meteorological Agency (JMA).
  • Individual users should provide JMA (jra@met.kishou.go.jp) with a copy of their scientific or technical papers, publications, press releases or other communications regarding these datasets.

b. Disclaimer

  • Although JMA has taken the utmost care in creating the datasets, it assumes no responsibility regarding their reliability. JMA is not responsible for any damage that may result from their use.

c. Intellectual property

  • The intellectual property rights of the datasets belong exclusively to JMA.

(The complete JMA and NCAR agreement for JRA-55 may be viewed via the Documentation tab.)

Air Temperature Atmospheric Heating Atmospheric Stability Brightness Temperature
Canopy Characteristics Cloud Frequency Cloud Liquid Water/Ice Convergence
Dew Point Temperature Evaporation Evapotranspiration Geopotential Height
Gravity Wave Heat Flux Heat Flux Humidity
Hydrostatic Pressure Ice Extent Land Surface Temperature Land Use/Land Cover Classification
Longwave Radiation Potential Temperature Precipitation Amount Precipitation Rate
Runoff Sea Level Pressure Shortwave Radiation Snow Depth
Snow Water Equivalent Soil Moisture/Water Content Soil Temperature Streamfunctions
Surface Pressure Surface Roughness Surface Winds Total Precipitable Water
Tropospheric Ozone Upper Air Temperature Upper Level Winds Vegetation Species
Vertical Wind Velocity/Speed Vorticity Water Vapor
GRIB parameter table: HTML | XML
Vertical Levels:
See the detailed metadata for level information.
Data Types:
Spatial Coverage:
Longitude Range: Westernmost=180W Easternmost=180E
Latitude Range: Southernmost=90S Northernmost=90N Detailed coverage information
Data Contributors:
Japan Meteorological Agency, Japan
Kobayashi, S., Y. Ota, Y. Harada, A. Ebita, M. Moriya, H. Onoda, K. Onogi, H. Kamahori, C. Kobayashi, H. Endo, K. Miyaoka, and K. Takahashi, 2015: The JRA-55 Reanalysis: General Specifications and Basic Characteristics J. Met. Soc. Jap., 93(1), 5-48 (DOI: 10.2151/jmsj.2015-001).

Chen, G., T. Iwasaki, H. Qin, and W. Sha, 2014: Evaluation of the Warm-Season Diurnal Variability over East Asia in Recent Reanalyses JRA-55, ERA-Interim, NCEP CFSR, and NASA MERRA J. Climate, 27(14), 5517-5537 (DOI: 10.1175/JCLI-D-14-00005.1).

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. Met. Soc. Jap., 85(3), 369-432 (DOI: 10.2151/jmsj.85.369).

Total Volume:
1.43 TB (Entire dataset) Volume details by dataset product
Data Formats:
Related RDA Datasets:
Japanese 25-year Reanalysis Project
Japanese 25-year Reanalysis Project, Monthly Means
ERA-20C Project (ECMWF Atmospheric Reanalysis of the 20th Century)
ERA-Interim Project
ERA-Interim Project, Monthly Means
ERA-Interim Project, Single Parameter 6-Hourly Surface Analysis and Surface Forecast Time Series
JRA-55: Japanese 55-year Reanalysis, Daily 3-Hourly and 6-Hourly Data
JRA-55C: The Japanese 55-year Reanalysis Using Conventional Data Only
JRA-55C: Monthly Means and Variances
JRA-55AMIP: The Japanese 55-year Reanalysis AMIP-type Simulation
JRA-55AMIP: Monthly Means and Variances Including Diurnal Statistics
JRA-55: Japanese 55-year Reanalysis, Near Real-Time Data
JRA-55: Japanese 55-year Reanalysis, Near Real-Time Data -- Monthly Means and Variances
ERA5 Reanalysis (0.25 Degree Latitude-Longitude Grid)
ERA5 Reanalysis (Monthly Mean 0.25 Degree Latitude-Longitude Grid)
ERA5.1: Corrections to ERA5 Stratospheric Temperature 2000-2006
ERA5 Modes of Interannual Variability
More Details:
View a more detailed summary of the data, including specific date ranges and locations by parameter
Metadata Record:
Data License:
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