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BMRC coupled modelling : - PowerPoint PPT Presentation

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BMRC coupled modelling :
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  1. BMRC coupled modelling: • Oscar Alves, Guomin Wang, Neville Smith, Aihong Zhong, Faina Tseitkin, Andrew Marshall • BMRC Model Development (NWP, Lilia Deschamps) • BMRC Climate Dynamics (Rob Colman) • CSIRO Marine Research (OGCM) • Andreas Schiller, Stuart Godfrey, Gary Meyers, Peter McIntosh, Russ Fieddler

  2. Biases in:POAMA (operational coupled seasonal forecast model) 9 month forecastsClimate Version: 100 yr run discard first 20 yrs, no flux correction

  3. GCM Components Atmospheric model BAM3 configuration Resolution: T47L17 Radiation: Lacis and Hansen (1974), Schwarzkopf and Fels (1991) Convection: Tiedtke (1989): moisture convergence and CAPE closures Land surface processes: Manabe and Holloway (1975). Prognostic Cloud formulation: Rotstayn (1997) Surface Fluxes: Louis (1983), McAvaney and Hess (1996) Ocean model ACOM2 configuration • Resolution: meridional 0.5° within 8° of the equator, Zonal 2°; 12 levels in the top 185 metres. • Chen mixing scheme • penetrtative short wave radiation • tidal mixing parameterisation in the Indonesian region • careful representation of islands and straits in the Indonesian region

  4. Operational Forecast Set Up • Ocean initial conditions Daily Optimum Interpolation • Atmos. initial conditions From BoM operational NWP model • Ensemble • 9 month forecast everyday (within 1 day of real time) • Anomalies from Model Climatology • Hindcast 1983-2002 • One per month, AMIP atmospheric initial condition • Assimilated oceanic initial condition

  5. SST Anomaly Correlation Skill with Lead Time Green - model Red - anomaly persistence

  6. NASA Decay of 2002 El Nino Forecasts available at BOM Dec 2002 SCO POAMA ECMWF NCEP

  7. SST drift: Problem with surface flux and clouds in stand-alone AGCM Little impact on east Pacific drift from big changes to StratCu: suggests resolution problem near Andes Convection: Changes to convection parameterization improve intraseasonal variability and ITCZs in uncoupled run Impacts coupled behavior (perhaps more realstic) Improvements to ITCZ don’t carry over to coupled run

  8. SST Drift

  9. Bias 100 yr climate run

  10. SRB “observed” Surf SW Surface short wave from AMIP run of AGCM

  11. AGCM Net Flux Drift at 6 month lead What ocean wants Diff

  12. Sub-surface drift suggests problem equatorial winds

  13. Erroneous mixing above Strat Cu Enhanced sub Strat Cu mixing

  14. Tropical intraseasonal variability Moisture convergence closure NCEP re-analysis CAPE Closure 30 days 60 days

  15. Mean Prec CAPE Mean Precip Moist Convergence

  16. Annual mean prec coupled climate run

  17. Zonal wind anomaly along equator Obs Moisture closure CAPE Closure

  18. SST anomaly along equatorForecast starting 1st June 1997 Obs Old: Moisture closure New: CAPE Closure

  19. NCEP Latent Heat Flux AGCM