Presentation on theme: "Parameter Sensitivity of a Coupled Climate Model"— Presentation transcript:
1 Parameter Sensitivity of a Coupled Climate Model Estimated Through DataAssimilationXueyuan LiuA. Köhl, D. StammerCEN (Center für Erdsystemfurschungund Nachhaltigkeit)Hamburg University1
2 Decadal PredictionThe highlights of decadal climate predictions up to date:1)initialization )uncertainties3) minimizing the influence of systematic model biases4)measurements of the skill of hindcastsApproach: A fully-coupled data assimilation was used to get the optimal oceanic initial conditions and control variables(JAMSTEC). Based on those, ensembles of hindcasts with implimentation of greenhouse gas forcing are carried out every one year to assess how the strategy works. A 20C run from 1913 shall also be done. Extra ensembles might be necessary in order to give statistics. Ensembles of decadal prediction is expected to give information on the climate of the coming century.
3 Contribution of Control Variables alphas=0 against alphas=climatologyhindcasts (alphas=0) against HadISSTThe two patterns of mean bias of SST( ) are almost opposite. Despite the differences in the amplitude, we can come to a conclusion that control alphas contribute to the improvement of a hindcast.
6 K7 System from Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Coupled Model---CFES (Coupled model for the Earth Simulator)● T42L24 AFES (Atmospheric GCM for the Earth Simulator) for AGCM● 1*1 degree, 45 vertical layers MOM3 for OGCM● IARC (International Arctic Research Center) Sea-ice model● MATSIRO (Minimal Advanced Treatments of Surface Interaction and Runoff) Model for landAssimilation Method-----4D-VARAssimilation periodforwardbackwardFirst guess fieldBest guess trajectoryObs
7 Improving Decadal Predictions Schematic view of the experimental configuration:9 mon… …1970198019902000Spinup run by IAU……First guess I.C.Assimilation Exp.by 4D-VARoptimizedFirst guess Exp.(Free run)1.5 monthJan 1980Jan 1981Jan 1982Ensemble Exp.(each with 3 members-shifted atmosphere)10 yrIn all:
8 The research leading to these results has received funding from the European Union 7th Framework Programme (FP ), under grant agreement n NACLIM