Japanese 25-year Reanalysis Project, Monthly Means

| DOI: 10.5065/G3AR-1091

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.

Temporal Range:
1979-01-01 00:00 +0000 to 2008-08-01 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:

(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)."

Air Temperature Atmospheric Heating Canopy Characteristics Cloud Frequency
Cloud Liquid Water/Ice Convergence Dew Point Temperature Evapotranspiration
Geopotential Height Gravity Wave Heat Flux Humidity
Hydrostatic Pressure Ice Extent Land Surface Temperature Longwave Radiation
Maximum/Minimum Temperature Potential Temperature Precipitation Amount Precipitation Rate
Runoff Sea Level Pressure Sea Surface Temperature Shortwave Radiation
Snow Snow Depth Snow Depth Snow Melt
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 Vertical Wind Velocity/Speed
Vorticity Water Vapor
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
Central Research Institute of Electric Power Industry, Japan
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.

Total Volume:
444.37 GB (Entire dataset) Volume details by dataset product
Data Formats:
netCDF, Binary (see dataset documentation)
Related RDA Datasets:
Japanese 25-year Reanalysis Project
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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