The second Japanese reanalysis project conducted by the Japan Meteorological Agency (JMA), which cover the period from 1958 onward.
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 Data Assimilation (DA) 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 DA systems and the current system creates a lack of long-term data homogeneity.
To produce a high-quality homogeneous climate dataset, a constant state-of-the-art DA 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 higher-quality and more homogeneous climate data for a variety of meteorological variables covering the last several decades.
Global reanalysis has been conducted at a number of major Numerical Weather Prediction centers (for more information, see http://www.reanalyses.org/). In Japan, the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry (CRIEPI) jointly conducted the Japanese 25-year Reanalysis (JRA-25, covering the period from 1979 to 2004) and completed in 2006 (Onogi et al. 2007).
JMA carried out the second reanalysis project (known as the Japanese 55-year Reanalysis, or JRA-55) using a more sophisticated DA system based on the operational system as of December 2009, and newly prepared dataset of past observations. The analysis period covers the 55 years from 1958, when regular radiosonde observation began on a global basis. Many of the deficiencies of JRA-25 are alleviated in JRA-55 because the DA system used for the project featured a variety of improvements introduced after JRA-25. As a result, the JRA-55 project produced a high-quality homogeneous climate dataset covering the last half century.
JRA-55 data are provided by collaborative organizations.
For remaking/updating of index files (*.idx) to support visualization with GrADS
Data access to JRA-55 (an atmospheric reanalysis) : http://search.diasjp.net/en/dataset/JRA55
Data access to JRA-55C (an atmospheric reanalysis assimilating conventional observations only) : http://search.diasjp.net/en/dataset/JRA55_C
Data access to JRA-55AMIP (JRA-55 AMIP-type simulation) : http://search.diasjp.net/en/dataset/JRA55_AMIP
Data access to JRA-55CHS (an atmospheric reanalysis assimilating conventional observations only with high resolution SST) : http://search.diasjp.net/en/dataset/JRA55_CHS
Data access to JRA-55 (an atmospheric reanalysis):
$ gribmap -b -i [data descriptor file]
If the change involves only the time period, the relevant information can simply be added to the existing file.
$ gribmap -b -u -i [data descriptor file]
Numerical Prediction Division, Information Infrastructure Department, Japan Meteorological Agency