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