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New Coupled Forecast System at the Japan Meteorological Agency

Introducing the latest ocean assimilation and coupled model for ENSO forecast with improved forecast skill. Explore forecast details and comparison with previous models.

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New Coupled Forecast System at the Japan Meteorological Agency

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  1. New Coupled Forecast System at the Japan Meteorological Agency Yuhei Takaya1 (ytakaya@met.kishou.go.jp), Tamaki Yasuda2, Satoshi Matsumoto2, Tosiyuki Nakaegawa2, Hirotaka Kamahori1 and Tomoaki Ose2 1. Climate Prediction Division, Japan Meteorological Agency 2. Meteorological Research Institute, Japan Meteorological Agency NOAA 32nd Annual Climate Diagnostics and Prediction Workshop,October 22-26, 2007, Tallahassee, Florida

  2. History of ENSO Monitoring and Forecast Service at JMA 1992 1996 1999 2003 2008 2010 Launch of ENSO Monitoring Service Start-up of Ocean Monitoring with the Operational Ocean Data Assimilation System (ODAS) Start-up of ENSO Forecast Service with the CGCM (JMA-CGCM) The Second Version of JMA’s CGCM (JMA-CGCM02) The New Version of JMA’s Coupled Forecast System (MOVE-G/MRI.COM, JMA/MRI-CGCM) Seasonal Forecast with a CGCM 2

  3. Table of Contents • Introduction ofa newJMA’s coupled forecast system for ENSO forecast • New ocean assimilation system (MOVE-G/MRI.COM) • New atmosphere-ocean coupled model (JMA/MRI-CGCM) • Forecast skill of ENSO and Asian summer monsoon • Summary

  4. JMA Forecast System for ENSO Prediction Coupled model (JMA/MRI-CGCM) Atmospheric model (JMA/MRI Unified AGCM) Ocean Data Assimilation System (MOVE/MRI.COM-G) Atmospheric Analysis (JRA-25, JCDAS) Coupler Ocean model(MRI.COM)

  5. Ocean Data Assimilation System (MOVE-G/MRI.COM) • MOVE (Multivariate Ocean Variational Estimation) System • Usui et al. (2006) • Ocean Model : MRI Community Ocean Model (MRI.COM) • 3D-VAR(T,S) • Observation Data: T, S on GTS, SST (COBE-SST, Ishii et al. 2005), SSH (TOPEX/POSEIDON, JASON-1, ERS-1,2, ENVISAT) • VerticalCoupledTemperature-Salinity EOF modesFujii and Kamachi(2003) • Incremental Analysis Update (IAU)

  6. Improvement of the thermocline variability shade: dT/dzlines: isotherms of 20°C The MOVE system represents the more realistic interannual variability of thermocline. TAO OBS. MOVE-G CURRENT

  7. Comparisonof Temperature Climatology The temperature climatology of MOVE system is relatively close to the climatology of WOA01. Forget, Heimbach, and Menemenlis (2006) CLIVAR/GODAE Meeting on Ocean Synthesis Evaluation

  8. Comparison of Salinity Climatology The salinity climatology of MOVE system is relatively close to the climatology of WOA01. Forget, Heimbach, and Menemenlis (2006) CLIVAR/GODAE Meeting on Ocean Synthesis Evaluation

  9. New Coupled Model (JMA/MRI-CGCM)

  10. Forecast Skill of SST in NINO3.4 ACC (NINO3.4) RMSE (NINO3.4) (°C ) red: JMA/MRI-CGCM blue: current operational model black: persistence Period: 1979-2005 1 member forecast started from the end of every month (NOT ensemble forecast)

  11. Forecast Skill of SST in WTP ACC (WTP) RMSE (WTP) (°C ) red: JMA/MRI-CGCM blue: current model black: persistence Period: 1979-2005 1 member forecast started from the end of every month (NOT ensemble forecast)

  12. Experimental Setting of the Retrospective Seasonal Forecast AUG JAN 10 members Jun.-Aug. 7 months 4-month lead • 10-member ensemble forecasts are started from the end of January.(Two-tier AGCM forecasts are started from Feb. 10th.) • Period of the retrospective forecast is 22 years (1984-2005). • CO2 concentration is updated during the retrospective forecast period. • Initial data for land model are climatology.

  13. Forecast Skill of Precipitation (JJA, 4 months lead) 10-member ensemble forecast started from around the end of January. Period of the retrospective forecast is 22 years (1984-2005). JJA mean precipitation is verified with CMAP analysis. The JMA/MRI-CGCM shows better skill than JMA’s two-tier operational model. ACC (Two-tier AGCM) ACC (JMA/MRI-CGCM) J L

  14. SST-Precipitation Relationship in WTP in Boreal Summer (c) Two-tier AGCM (b) JMA/MRI-CGCM (a) Observation • Why CGCMs can predict precipitation better than AGCMs ? Negative Correlation Temporal correlation coefficients between JJA mean precipitation and JJA mean SST from (a) CMAP and COBE-SST analysis, (b)JMA/MRI-CGCM, (c)JMA two-tier operational model. eg. Wang et al. 2004, Wang et al. 2005, Kitoh and Arakawa 1999, Kobayashi et al. 2005

  15. Forecast Skill of Webster-Yang Index (JJA, 4 months lead) JMA/MRI-CGCM ACC=0.64 (m/s) 10-member ensemble Init: the end of Jan. Period:1984-2005 Ref. : JRA-25 JJA mean Two-tier AGCM ACC=0.47 (m/s) Webster-Yang index: U850(EQ-20N, 40-110E) –U200(EQ-20N, 40-110E) Webster and Yang (1992)

  16. Forecast Skill of East Asian Summer Monsoon (JJA, 4 months lead) JMA/MRI-CGCM ACC=0.58 (m/s) 10-member ensemble Init: the end of Jan. Period:1984-2005 Ref. : JRA-25 JJA mean ACC=0.04 Two-tier AGCM (m/s) cf. Kug et al. (2007) DU2 index: U850(5-15N, 90-130E) -U850(22.5-32.5N, 110-140E) Wang and Fan (1999)

  17. ROC Score of 850 hPa Temperature (upper tercile, JJA, 4 months lead) ROC (JMA/MRI-CGCM) ROC (Two-tier AGCM) J L ROC Area (tropics) : 0.65 ROC Area (tropics) : 0.59 • 10-member ensemble forecast started from around the end of January. • Period of the retrospective forecast is 22 years (1984-2005). • JJA mean temperature at 850 hPa is verified with JRA-25. cf. Graham et al. (2005)

  18. Summary and Future Plans The JMA/MRI-CGCM shows better forecast skill of Nino3.4 SST than the current operational ENSO forecast model. (The ACC is more than 0.7 at a lead time of 6 months.) The JMA/MRI-CGCM shows better forecast skill of the Asian summer monsoon circulation (W-Y index and DU2 index) and precipitation compared with the current operational two-tier system. The JMA’s new coupled forecast system for ENSO prediction will be operated in early 2008. JMA now plans to improve the JMA/MRI-CGCM as a seasonal forecast model and start one-tier forecast in 2010.

  19. Thank you for your kind attention. JMA’s mascot “Harerun”

  20. References Fujii, Y., and M. Kamachi (2003), Three-dimensional analysis of temperature and salinity in the equatorial Pacific using a variational method with vertical coupled temperature-salinity empirical orthogonal function modes, J. Geophys. Res., 108(C9), 3297, doi:10.1029/2002JC001745. Graham, R. J., M. Gordon, P. J. Mclean, S. Ineson, M. R. Huddleston, M. K. Davey, A. Brookshaw, R. T. H. Barnes (2005), A performance comparison of coupled and uncoupled versions of the Met Office seasonal prediction general circulation model, Tellus A, Volume 57, Number 3, May 2005 , pp. 320-339(20) Kitoh, A, O. Arakawa (1999), On overestimation of tropical precipitation by an atmospheric GCM with prescribed SST. Geophys. Res. Lett. 26:2965-2968 Kobayashi, C., S. Maeda, A. Ito, Y. Matsushita and K. Takano (2005), Relation between SSTs and Predictability of Seasonal Mean Precipitation over the Western Tropical Pacific. JMSJ, Vol. 83, 919-929. Kug, J.-S., I.-S. Kang and D.-H. Choi (2007): Seasonal climate predictability with Tier-one and Tier-two prediction systems, Clim. Dyn., DOI 10.1007/s00382-007-0264-7 Usui, N., S. Ishizaki, Y. Fujii, H. Tsujino, T. Yasuda, M. Kamachi (2006), Meteorological Research Institute Multivariate Ocean Variational Estimation (MOVE) System: Some early results. Adv. Space Res. 37, 806-822 Wang, B. and Z. Fan (1999), Choice of South Asian summer monsoon indices. Bull. Amer. Meteor. Soc., 80, 629-638, 1999. Wang, B., I.-S. Kang and J. -Y. Lee (2004), Ensemble Simulations of Asian-Australian Monsoon Variability by 11 AGCMs. J. Climate, 17, 4, 803-818. Wang, B., Q. Ding, X. Fu, I.-S. Kang, K. Jin, J. Shukla, and F. Doblas-Reyes (2005), Fundamental challenge in simulation and prediction of summer monsoon rainfall, Geophys. Res. Lett., 32, L15711, doi:10.1029/2005GL022734. Webster, P. J. and S. Yang: Monsoon and ENSO (1992), Selectively interactive systems. Quart. J. Roy. Meteor. Soc., 118, 877-926.

  21. History of ENSO Monitoring and Forecast Service at JMA 1992 1996 1999 2003 2008 2010 Launch of ENSO Monitoring Service Start-up of Ocean Monitoring with the Operational Ocean Data Assimilation System (ODAS) Start-up of ENSO Forecast Service with the CGCM (JMA-CGCM) The Second Version of JMA’s CGCM (JMA-CGCM02) The New Version of JMA’s Coupled Forecast System (MOVE-G/MRI.COM, JMA/MRI-CGCM) Seasonal Forecast with a CGCM 22

  22. System design of MOVE/MRI.COM Past MRI.COM（OGCM） prediction Assimilation Climatology Observation ・temperature ・salinity ・SSH first-guess Coupled T-S EOF 3DVAR POpULar Gridded analysis fields Future IAU prediction Assimilation MRI.COM

  23. VerticalCoupled T-S EOF Modes Domain segmentation forvertical coupled T-SEOF modes 1st 2nd 3rd 4th 5th Vertical coupledT-S EOF modes for a red box region Temperature SaIinity Fujii and Kamachi (2003)

  24. Impact on the Warm Water Heat Content (WHC) BLT (Color) at Eq. WHC=10 (Black line) Difference of WHC (cal/cm2) (With S correction – without S correction) Thick barrier layer area has good correspondence with the area of large WHC. WHC: Heat content in warm water (>28 °C） WHC decreases in the thick barrier layer area because of bad barrier layer expression.

  25. Salinity Impact on the Equatorial Undercurrent With Salinity Correction 1993-2001 mean Eq-140W Sep96-Aug01 mean Tao EUC is weak without S correction Without S Without Salinity Correction 1993-2001 mean With S The profile with S correction is closer to the observed profile

  26. Forecast Skill of SST (JJA, started from JAN) ACC (Two-tier AGCM) ACC (JMA/MRI-CGCM) MSSS (Two-tier AGCM) MSSS (JMA/MRI-CGCM) • 10-member ensemble forecast started from around the end of January. • Period of the retrospective forecast is 22 years (1984-2005). • JJA mean SST is verified with COBE-SST analysis.

  27. Forecast Skill of SST (DJF, started from JUL) ACC (Two-tier AGCM) ACC (JMA/MRI-CGCM) MSSS (Two-tier AGCM) MSSS (JMA/MRI-CGCM) • 10-member ensemble forecast started from around the end of July. • Period of the retrospective forecast is 22 years (1984-2005). • DJF mean SST is verified with COBE-SST analysis.

  28. Forecast Skill of T2m (JJA, started from JAN) ACC (Two-tier AGCM) ACC (JMA/MRI-CGCM) MSSS (Two-tier AGCM) MSSS (JMA/MRI-CGCM) • 10-member ensemble forecast started from around the end of January. • Period of the retrospective forecast is 22 years (1984-2005). • JJA mean T2m is verified with JRA-25.

  29. Forecast Skill of T2m (DJF, started from JUL) ACC (Two-tier AGCM) ACC (JMA/MRI-CGCM) MSSS (Two-tier AGCM) MSSS (JMA/MRI-CGCM) • 10-member ensemble forecast started from around the end of July. • Period of the retrospective forecast is 22 years (1984-2005). • DJF mean T2m is verified with JRA-25.

  30. ROC Area of 2-m Temperature (JJA, upper tercile) ROC Area (JMA/MRI-CGCM) ROC Area (Two-tier AGCM) ROC Area (tropics) : 0.64 ROC Area (tropics) : 0.60 • 10-member ensemble forecast started from around the end of January. • Period of the retrospective forecast is 22 years (1984-2005). • JJA mean temperature at 2 m height is verified with JRA-25. cf. Graham et al. (2005)

  31. ROC Area of 2-m Temperature (DJF, upper tercile) ROC Area (JMA/MRI-CGCM) ROC Area (Two-tier AGCM) ROC Area (tropics) : 0.68 ROC Area (tropics) : 0.66 • 10-member ensemble forecast started from around the end of July. • Period of the retrospective forecast is 22 years (1984-2005). • DJF mean temperature at 2 m height is verified with JRA-25. cf. Graham et al. (2005)

  32. ROC Area of 850 hPa Temperature (JJA, upper tercile) ROC Area (JMA/MRI-CGCM) ROC Area (Two-tier AGCM) ROC Area (tropics) : 0.65 ROC Area (tropics) : 0.59 • 10-member ensemble forecast started from around the end of January. • Period of the retrospective forecast is 22 years (1984-2005). • JJA mean temperature at 850 hPa is verified with JRA-25.

  33. ROC Area of 850 hPa Temperature (DJF, upper tercile) ROC Area (JMA/MRI-CGCM) ROC Area (Two-tier AGCM) ROC Area (tropics) : 0.69 ROC Area (tropics) : 0.67 • 10-member ensemble forecast started from around the end of July. • Period of the retrospective forecast is 22 years (1984-2005). • DJF mean temperature at 850 hPa is verified with JRA-25.

  34. ROC Area of SLP (DJF, upper tercile) ROC Area (JMA/MRI-CGCM) ROC Area (Two-tier AGCM) ROC Area (tropics) : 0.6 ROC Area (tropics) : 0.5 • 10-member ensemble forecast started from around the end of July. • Period of the retrospective forecast is 22 years (1984-2005). • DJF mean temperature at 850 hPa is verified with JRA-25.

  35. ROC of T850 (JJA, upper tercile) ROC (JMA/MRI-CGCM) ROC (Two-tier AGCM) • 10-member ensemble forecast started from around the end of Jan. • Period of the retrospective forecast is 22 years (1984-2005). • DJF mean temperature at 850 hPa is verified with JRA-25.

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