JRA-3Q project Japanese >> JRA project Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) The third Japanese reanalysis project conducted by the Japan Meteorological Agency (JMA), which covers the period from September 1947 onward. Latest News 2 February 2026 A JRA-3Q evaluation paper (Harada et al. 2026) is now available from the Quarterly Journal of the Royal Meteorological Society. 2 December 2025 The URL of this website has changed as follows: Old URL: https://jra.kishou.go.jp/ New URL: https://www.data.jma.go.jp/jra/html/ An automatic redirection to the new URL is in place for the time being. Please update your favorites or bookmarks if the old URL is saved. 25 February 2025 The JRA-3Q comprehensive report (Kosaka et al. 2024) was presented with the JMSJ award. The early online release of a JRA-3Q evaluation paper (Naoe et al. 2025) is now available from the Journal of the Meteorological Society of Japan. Archive >> Reanalysis Reanalysis Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) Sub-product JRA-3Q-COBE JRA-3Q comprehensive report References Links Reanalysis The need for quantitative assessment of past and current climate conditions gives rise to the requirement for a high-quality dataset with homogeneity in space and time to support climate research and related services such as seasonal forecasts, extreme weather analysis and climate monitoring. The quality of analysis produced by the operational numerical weather prediction (NWP) system has improved remarkably in recent years due to advances made with the system. Consequently, the difference in the quality of analysis produced with previous operational NWP systems and the current system creates a lack of long-term data homogeneity. To produce a high-quality homogeneous dataset, a constant state-of-the-art data assimilation system is used in reanalysis. In addition, as many observations as possible are collected, including those used in past operational systems and delayed observations as well as digitized observations. High-quality reprocessed satellite data are also assimilated where available. These approaches enable the production of a higher-quality and more homogeneous dataset for a variety of meteorological variables covering the last several decades. Global reanalysis has been conducted at a number of major NWP centers (for more information, see https://reanalyses.org/). In this context, the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry (CRIEPI) in Japan jointly conducted the Japanese 25-year Reanalysis (JRA-25, covering the period from 1979 to 2004 and completed in 2006), and JMA conducted the Japanese 55-year Reanalysis (JRA-55, covering the period from 1958 onward and completed in 2013). Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) JMA is currently conducting the Japanese Reanalysis for Three Quarters of a Century (JRA-3Q), which covers the period from September 1947 onward to extend the current period of data coverage and improve the quality of long-term reanalysis. The project involves a sophisticated data assimilation system (based on the operational set-up as of December 2018) incorporating development results from the operational NWP system and sea surface temperature analysis achieved since JRA-55 (based on the operational set-up as of December 2009). New datasets of past observations are also assimilated, including rescued historical observations and reprocessed satellite data supplied by meteorological and satellite centers worldwide. Many of the deficiencies of JRA-55 are alleviated in JRA-3Q, providing a high-quality homogeneous reanalysis dataset that covers the previous 75 years. Sub-product JRA-3Q-COBE In JRA-3Q, the sea surface temperature (SST) specified as the lower boundary condition is the Centennial In Situ Observation-based Estimates of the Variability of SSTs and Marine Meteorological Variables Version 2 (COBE-SST2) with a resolution of 1° based on in situ observations until May 1985 and the Merged Satellite and In-Situ Data Global Daily Sea Surface Temperature (MGDSST) with a resolution of 0.25° based on satellite observations since June 1985. To enable evaluation of changes in product characteristics following the switch from COBE-SST2 to MGDSST, a sub-product using COBE-SST2 (JRA-3Q-COBE) is also provided for the period from June 1985 to December 1990. JRA-3Q comprehensive report Reference JRA-3Q data in scientific or technical papers should be cited to the JRA-3Q comprehensive report below. Kosaka, Y., S. Kobayashi, Y. Harada, C. Kobayashi, H. Naoe, K. Yoshimoto, M. Harada, N. Goto, J. Chiba, K. Miyaoka, R. Sekiguchi, M. Deushi, H. Kamahori, T. Nakaegawa, T. Y. Tanaka, T. Tokuhiro, Y. Sato, Y. Matsushita, and K. Onogi, 2024: The JRA-3Q reanalysis. J. Meteor. Soc. Japan, 102, 49-109, https://doi.org/10.2151/jmsj.2024-004. References Harada, Y., S. Kobayashi, Y. Kosaka, J. Chiba, and T. Y. Tanaka, 2026: Quality evaluation of the precipitation over the tropical oceans in the JRA-3Q reanalysis. Quart. J. Roy. Meteor. Soc., 152, e70026, https://doi.org/10.1002/qj.70026. Naoe, H., C. Kobayashi, S. Kobayashi, Y. Kosaka, and K. Shibata, 2025: Representation of quasi-biennial oscillation in JRA-3Q. J. Meteor. Soc. Japan, 103, 233-255, https://doi.org/10.2151/jmsj.2025-012. Links 6th WCRP International Conference on Reanalysis Joint WCRP-WWRP Symposium on Data Assimilation and Reanalysis and 2021 ECMWF Annual Seminar on Observations Usage of JRA-3Q How to obtain data Data source acknowledgement Remaking metafiles for JRA-3Q data visualization How to obtain data The data are widely provided to the public through the Japan Meteorological Business Support Center (JMBSC). If you would like to use JRA-3Q data, please obtain the data from JMBSC. For more information, please visit the JMBSC website. JRA-3Q data are also provided by collaborative organizations for non-commercial purposes. Please note the following in regard to downloading data from these organizations: Collaborative organizations are separate entities from JMA and are solely responsible for their own web portals and data access procedures. User registration and agreement to terms and conditions of data service usage are required individually for each organization. Collaborative organizations DIAS: Data Integration & Analysis System DIAS service is currently undergoing long-term maintenance, and all datasets provided by DIAS are inaccessible. Data access to JRA-3Q Metadata page: https://search.diasjp.net/en/dataset/JRA3Q, DOI: 10.20783/DIAS.645 Data access to JRA-3Q-COBE (JRA-3Q with COBE-SST2) Metadata page: https://search.diasjp.net/en/dataset/JRA3Q_COBE, DOI: 10.20783/DIAS.661 When publishing results using data provided from DIAS, please cite the dataset in addition to the above-mentioned JRA-3Q comprehensive report (see each metadata page as to how to cite the dataset). NCAR: National Center for Atmospheric Research Data access to JRA-3Q Metadata page: https://gdex.ucar.edu/datasets/d640000, DOI: 10.5065/AVTZ-1H78 Data access to Near Real-Time JRA-3Q Metadata page: https://gdex.ucar.edu/datasets/d640001, DOI: 10.5065/E3QQ-0F24 Data access to JRA-3Q Monthly Statistics Metadata page: https://gdex.ucar.edu/datasets/d640002, DOI: 10.5065/PH0D-MH18 Data access to Near real-time monthly mean JRA-3Q Metadata page: https://gdex.ucar.edu/datasets/d640003, DOI: 10.5065/CW01-2282 Data access to JRA-3Q Diurnal Statistics Metadata page: https://gdex.ucar.edu/datasets/d640004, DOI: 10.5065/PK9Z-C990 Data access to Near real-time monthly diurnal JRA-3Q Metadata page: https://gdex.ucar.edu/datasets/d640005, DOI: 10.5065/4Q9N-SG67 Data access to JRA-3Q-COBE Metadata page: https://gdex.ucar.edu/datasets/d640006, DOI: 10.5065/RM7V-3X70 When publishing results using data provided from NCAR, please cite the dataset in addition to the above-mentioned JRA-3Q comprehensive report (see each metadata page as to how to cite the dataset). Data source acknowledgement JRA-3Q data should be acknowledged in scientific and technical reports. Example This report references JRA-3Q reanalysis data from the Japan Meteorological Agency. This report references JRA-3Q-COBE reanalysis data from the Japan Meteorological Agency. Remaking metafiles for JRA-3Q data visualization Data descriptor files (*.ctl) and index files (*.idx) can be used in addition to JRA-3Q data for visualization of JRA-3Q data with multi-purpose Grid Analysis and Display System (GrADS) software. When information in data descriptor files (e.g., time periods and other variables) is changed, the corresponding index files need to be remade. To remake an index file $ gribmap -b -i [data descriptor file] JRA-3Q Data Format These documents give an overview of JRA-3Q data. 9 December 2022 1.25-degree latitude/longitude grid data model grid data Adobe Reader&reg; must be installed to enable viewing of Portable Document Format (PDF) files. Quality Issues Local issues with sea ice parameters Report (9 December 2022) Contact Us Contact JMA at the email address below with any questions on JRA-3Q. Numerical Prediction Division, Information Infrastructure Department, Japan Meteorological Agency Numerical Prediction Division, Information Infrastructure Department &copy; 2022 Japan Meteorological Agency < Legal Notice>