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JRA-55the Japanese 55-year reanalysis project

- status and plan -

Climate Prediction DivisionJapan Meteorological Agency

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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

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Overview of JRA-55

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

Phase 2 (2013~2015)

Regional downscaling over Japan (1958~2012)

Details to be determined

Boundary fields

60-km resolution global climate data set

High-resolution (~5 km) climate data set over Japan

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Observations for JRA-55

First time for reanalyses

Improved from or added to JRA-25

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Specifications of data assimilation system

JRA-25 (1979~2004) JRA-55 (1958~2012)

Resolution T106L40 (~120km)(top layer at 0.4 hPa)

TL319L60 (~60km)(top layer at 0.1 hPa)

Time integration Eularian Semi-Lagrangian

Long-wave radiation

Line absorptionStatistical band model

Water vapor continuume-type

Line absorptionTable lookup + K-distribution

Water vapor continuume-type + p-type

Assimilation scheme 3D-Var 4D-Var

(with T106 inner model)

B matrix ConstantDifferent B matrices for

pre-satellite and satellite eras

Bias correction(radiosonde)

Radiation bias only(Andrae et al., 2004)

RAOBCORE v1.4(Haimberger, 2007, J. Climate)

Bias correction(radiances)For satellite

Offline Variational Bias Correction

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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 thorough QC 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)

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Boundary and forcing fields

JRA-25 (1979~2004) JRA-55 (1958~2012)

Radiatively active gases

H2O, CO2, O3

H2O, CO2, O3, CH4, N2O, CFC-11, CFC-12, HCFC-22

GHG concentrations

Constant at 375 ppmv (CO2)

vary over time

Ozone Daily 3-D ozone(produced by AED/JMA)

(-1978) Monthly climatology(1979-) New daily 3-D ozone

(produced using a revised CTM)

AerosolsAnnual climatology for

continental and maritime aerosols

Monthly climatology for continental and maritime

aerosols

SSTSea ice

COBE SST(Ishii et al., 2005, I.J.Clim.)

COBE SST(Same as JRA-25)

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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

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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.

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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.