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Parameter Sensitivity of a Coupled Climate Model

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Presentation on theme: "Parameter Sensitivity of a Coupled Climate Model"— Presentation transcript:

1 Parameter Sensitivity of a Coupled Climate Model
Estimated Through Data Assimilation Xueyuan Liu A. Köhl, D. Stammer CEN (Center für Erdsystemfurschung und Nachhaltigkeit) Hamburg University 1

2 Decadal Prediction The highlights of decadal climate predictions up to date: 1)initialization )uncertainties 3) minimizing the influence of systematic model biases 4)measurements of the skill of hindcasts Approach: 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=climatology hindcasts (alphas=0) against HadISST The 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.

4 Annual-mean SST over 9 Years

5 Thanks for your attention!

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 land Assimilation Method-----4D-VAR Assimilation period forward backward First guess field Best guess trajectory Obs

7 Improving Decadal Predictions
Schematic view of the experimental configuration: 9 mon … … 1970 1980 1990 2000 Spinup run by IAU …… First guess I.C. Assimilation Exp. by 4D-VAR optimized First guess Exp. (Free run) 1.5 month Jan 1980 Jan 1981 Jan 1982 Ensemble Exp. (each with 3 members- shifted atmosphere) 10 yr In all:

8 The research leading to these results has received funding from the European Union 7th Framework Programme (FP ), under grant agreement n NACLIM

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