The Japanese 55-year Reanalysis "JRA-55"

• Published in: Scientific online letters on the atmosphere Vol. 7; p. 149
• Main Authors: Ebita, Ayataka, Kobayashi, Shinya, Ota, Yukinari, Moriya, Masami, Kumabe, Ryoji, Onogi, Kazutoshi, Harada, Yayoi, Yasui, Soichiro, Miyaoka, Kengo, Takahashi, Kiyotoshi, Kamahori, Hirotaka, Kobayashi, Chiaki, Endo, Hirokazu, Soma, Motomu, Oikawa, Yoshinori, Ishimizu, Takahisa
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 01.01.2011
• ISSN: 1349-6476

The Japan Meteorological Agency (JMA) started the second Japanese global atmospheric reanalysis project named the Japanese 55-year Reanalysis (JRA-55). It covers 55 years, extending back to 1958, when the global radiosonde observing system was established. Many of the deficiencies found in the first Japanese reanalysis, the Japanese 25-year Reanalysis (JRA-25), have been improved. It aims at providing a comprehensive atmospheric dataset that is suitable for studies of climate change or multi-decadal variability, by producing a more time-consistent dataset for a longer period than JRA-25. Production of JRA-55 started in 2010, and computations for more than 16 years have been completed as of August 2011. The entire JRA-55 production will be completed in early 2013 and thereafter JRA-55 will be continued as a new JCDAS on real time basis. This paper is a brief report to introduce the JRA-55 reanalysis project. The data assimilation and prediction (DA) system used in JRA-55 is introduced and compared to that used in JRA-25. Early results of JRA-55 are presented and discussed, showing general improvements.