JRA-55 the Japanese 55-year reanalysis project - status and plan -

1. JRA-55the Japanese 55-year reanalysis project- status and plan - Climate Prediction Division Japan Meteorological Agency

2. JMA’s current Climate Data Assimilation System • JRA-25(1979~2004) production finished in 2006 • jointly conducted by JMA and Central Research Institute of Electric Power Industry (CRIEPI) • freely available for research purposes • http://jra.kishou.go.jp/JRA-25/index_en.html • A full copy of the JRA-25 data set provided to NCAR • http://dss.ucar.edu/datasets/ds625.0/ • continued as JCDAS (2005~) • available 2 days behind the real time • Over 1,300 registered users and 100 cited references as of Sep 2009 • The JRA-25 paper (Onogi et al., 2007, JMSJ) • http://www.jstage.jst.go.jp/article/jmsj/85/3/85_369/_article • extensively used for many activities at JMA • real-time climate monitoring, verification of seasonal forecasts, atmospheric forcing fields for the ocean data assimilation, chemical transport simulations and so on

3. Overview of JRA-55 60-km resolution global climate data set providing a fundamental data set for • researches on climate change and decadal variability in the last half century • real-time climate monitoring • verification of seasonal forecast and climate models • atmospheric forcing fields for ocean data assimilations • chemical transport simulations • carbon cycle simulations • water resource management • estimation of renewable energy resources • severe weather risk assessment and much more Phase 1 (2009~2012) JRA-55 (1958~2012) Reanalysis of past observations using a constant state-of-the-art data assimilation system Boundary fields Phase 2 (2013~2015) Regional downscaling over Japan (1958~2012) Details to be determined High-resolution (~5 km) climate data set over Japan

4. Observations for JRA-55 First time for reanalyses Improved from or added to JRA-25

5. Specifications of data assimilation system

6. Other changes from the JRA-25 system • Revised short-wave radiation scheme • Retuned absorption coefficients for O3, CO2 and O2 • Added more bands for CO2 and O2 • Enhanced QC for conventional data • Application of thoroughQC procedures for conventional data • Revised QC thresholds for conventional data • Improved treatment of cloud effects in the radiation scheme • Revised treatment of vertically overlapping clouds • Retuned cloud radiative properties • Introduction of a convective triggering scheme into the deep convective parameterization • Updated radiative transfer model for satellite radiances • Introduction of RTTOV-9 (Saunders et al., 2008)

7. Boundary and forcing fields

8. JRA-55 production schedule • Jul 2010 start of Stream B • Sep 2010 start of Stream A • Early 2013 completion of production • Mid 2013 product release • Production will be continued as a new JCDAS

9. Summary • JRA-55 improves upon JRA-25 in many respects, • a longer reanalysis period, extending back in 1958, • much better forecast performance than JRA-25, • significantly reduced cold bias in the lower stratosphere, and • reduced dry bias over the Amazon basin. • Quality of analysis changes inevitably due to changes in observing systems, but there is a good prospect that a reasonably homogeneous analysis will be produced in the northern hemisphere troposphere. • Quality of analysis is reasonablely high over the regions that radiosondes cover even if no satellite data is available. • On the other hand, it is anticipated that analyses of the pre-satellite era would degrade seriously in the southern hemisphere troposphere.

10. Summary (cont.) • There is a considerable possibility that quality of analysis in the pre-satellite era will improve by tuning the background error. • An experiment with a global constant scaling factor showed a small but positive result in the southern hemisphere. • The JRA-55 production is planned to start in Jun 2010 and expected to complete by early 2013.