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THOR Annual Meeting - Bergen 9-11 November 2011 1/25 On the impact of initial conditions relative to external forcing on the skill of decadal predictions:

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Presentation on theme: "THOR Annual Meeting - Bergen 9-11 November 2011 1/25 On the impact of initial conditions relative to external forcing on the skill of decadal predictions:"— Presentation transcript:

1 THOR Annual Meeting - Bergen 9-11 November /25 On the impact of initial conditions relative to external forcing on the skill of decadal predictions: preliminary results with the ECMWF coupled system Susanna Corti European Centre for Medium-Range Weather Forecasts With contributions from Magdalena Balmaseda, Per Kållberg, Linus Magnusson and Tim Palmer

2 THOR Annual Meeting - Bergen 9-11 November /25

3 THOR Annual Meeting - Bergen 9-11 November /25 (EXP1) Surface Temperature Anomaly Correlation Coefficients YR month average

4 THOR Annual Meeting - Bergen 9-11 November /25 (EXP1) Near Surface Temperature Anomaly Correlation Coefficients YR month average- Linear Climate trend out

5 THOR Annual Meeting - Bergen 9-11 November /25 (EXP1) Near Surface Temperature Anomaly Correlation Coefficients YR month average Climate trend in Climate trend out Anom. Init. Flux Cor. Full Init. Flux Cor. Volc. in Full Init. Volc. in Full Init. Anom. Init. Flux Cor. Full Init. Volc. in Flux Cor. Volc. in

6 THOR Annual Meeting - Bergen 9-11 November /25 (EXP1) Near Surface Temperature Anomaly Correlation Coefficients YR month average Climate trend in Climate trend out Anom. Init. Flux Cor. Full Init. Flux Cor. Volc. in Full Init. Volc. in Full Init. Anom. Init. Flux Cor. Full Init. Volc. in Flux Cor. Volc. in

7 THOR Annual Meeting - Bergen 9-11 November /25 (EXP2) Near Surface Temperature Anomaly Correlation Coefficient [Climate trend out] YR month averageYR month average Grand Ensemble of all (EXP1) experiments - 27 Ensemble members Near Surface Temperature Anomaly Correlation Coefficients [Climate trend out] YR month averageYR month average

8 THOR Annual Meeting - Bergen 9-11 November /25 Grand Ensemble of all (EXP1) experiments - 27 Ensemble members YR month average Cor=0.95, SPREAD/RMSE=0.63 YR month average Cor=-0.01, Climate forcing out AMO index YR month average Cor=0.78, SPREAD/RMSE=0.82 YR month average Cor=0.9, Climate forcing out T2m

9 THOR Annual Meeting - Bergen 9-11 November /25 10-year integrations with 5-member ensembles from: A 1965 initial conditions, observed forcing (GHG & aerosols) from 1965 (control1) B 1995 initial conditions, observed forcing (GHG & aerosols) from 1995 (control2) C 1965 initial conditions, observed forcing from 1995 D 1995 initial conditions, observed forcing from 1965 By comparing A with D, and B with C, we have two estimates of decadal predictability (arising from having different initial conditions and the same GHG forcing). By comparing A with C, and B with D, we have two estimates of the impact of GHG forcings (since initial conditions are the same) Experiment

10 THOR Annual Meeting - Bergen 9-11 November /25 1yr Running mean - Global SSTs FOR INI

11 THOR Annual Meeting - Bergen 9-11 November /25 1yr Running mean - Indian Ocean SSTs INI FOR

12 THOR Annual Meeting - Bergen 9-11 November /25 1yr Running mean - North Atlantic SSTs INI FOR

13 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

14 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

15 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

16 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

17 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

18 THOR Annual Meeting - Bergen 9-11 November /25 RianalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

19 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

20 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

21 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

22 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

23 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

24 THOR Annual Meeting - Bergen 9-11 November /25 ReanalysisControl SSTs: [ ] - [ ] Ctl95-FOR65 FOR95-Ctl65 Ctl95-INI65 INI95-Ctl65

25 THOR Annual Meeting - Bergen 9-11 November /25 Summary The decadal prediction experiments show a positive forecast quality that can be statistically significant over several areas. When the linear climate trend is subtracted some regions (common to all the experiments carried out) of more pronounced predictability have been identified. Preliminary results of the experiment indicate that over time scales longer than 5 years predictability arises mainly from the forcing. The correct initialisation has a strong impact up to about 1 year on a global domain, but it seems to affect the predictability over the North Atlantic up to 5 years.

26 THOR Annual Meeting - Bergen 9-11 November /25 Reliability diagram Poor resolution Good resolution Reliability score (the smaller, the better) Resolution score (the bigger, the better) c c Size of red bullets represents number of forecasts in probability category (sharpness)

27 THOR Annual Meeting - Bergen 9-11 November /25 Brier Skill Score & Reliability Diagram How to construct the area of positive skill? perfect reliability Observed Frequency Forecast Probability line of no skill area of skill (RES > REL) climatological frequency (line of no resolution)

28 THOR Annual Meeting - Bergen 9-11 November /25 Grand Ensemble of all (EXP1) experiments - 27 Ensemble members Reliability diagrams - T2m yr T2m anomaly below the lower tercile - Global T2m anomaly above the upper tercile - Global

29 THOR Annual Meeting - Bergen 9-11 November /25 Grand Ensemble of all (EXP1) experiments - 27 Ensemble members Reliability diagrams - T2m yr T2m anomaly below the lower tercile - Global T2m anomaly above the upper tercile - Global

30 THOR Annual Meeting - Bergen 9-11 November /25 T2m anomaly below the lower tercile - Global Linear Climate trend out T2m anomaly above the upper tercile - Global Linear Climate trend out Grand Ensemble of all (EXP1) experiments - 27 Ensemble members Reliability diagrams - T2m yr

31 THOR Annual Meeting - Bergen 9-11 November /25

32 THOR Annual Meeting - Bergen 9-11 November /25

33 THOR Annual Meeting - Bergen 9-11 November /25


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