Large Improvement in CFS Prediction Skill by Regime Dependent

Bias Correction

Wilbur Y. ChenClimate Prediction Center

NCEP/NWS/NOAA

MDL

OBS

Bias =MDL - OBS

Mdl

Obs

Mdl Bias =Mdl - Obs

Raw fcst skill

Model bias corrected skill

Distinct in time-mean flows

Bias forWarm events

Bias for Cold events

Bias for Neutral events

Bias for warm DJFs

Bias for cold DJFs

Bias for neutral DJFs

Lead = 1 month Lead = 4 months Lead = 6 months

Conventional forecast

Verification

Improved forecast

Large improvement in AC skill by Regime Dependent Bias Correction

Regime dependent bias corrected

Conventional mdl bias corrected

Raw predictions