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

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

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) 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 Ocean model ACOM2 configuration

Operational Forecast Set Up Ocean initial conditionsDaily Optimum Interpolation Atmos. initial conditionsFrom BoM operational NWP model Ensemble –9 month forecast everyday (within 1 day of real time) Anomalies from Model Climatology –Hindcast –One per month, AMIP atmospheric initial condition –Assimilated oceanic initial condition

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

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

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

SST Drift

Bias 100 yr climate run

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

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

Sub-surface drift suggests problem equatorial winds

Enhanced sub Strat Cu mixing Erroneous mixing above Strat Cu

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

Mean Prec CAPE Mean Precip Moist Convergence

Annual mean prec coupled climate run

Zonal wind anomaly along equator ObsMoisture closureCAPE Closure

SST anomaly along equator Forecast starting 1 st June 1997 ObsOld: Moisture closureNew: CAPE Closure

Latent Heat Flux NCEP AGCM