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Susanna Corti

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. With contributions from Magdalena Balmaseda & Linus Magnusson.

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Susanna Corti

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  1. 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 With contributions from Magdalena Balmaseda& LinusMagnusson Thanks to KristianMogensen and Tim Stockdale for the help in the experimental setup

  2. (EXP1) Surface Temperature Anomaly Correlation Coefficients YR 2-5 12-month average

  3. (EXP1) Near Surface Temperature Anomaly Correlation Coefficients YR 2-5 12-month average- Linear Climate trend out

  4. (EXP1) Near Surface Temperature Anomaly Correlation Coefficients YR 2-5 12-month average Full Init. Full Init. Anom. Init. Anom. Init. Climate trend in Flux Cor. Flux Cor. Climate trend out Full Init. Volc. in Full Init. Volc. in Flux Cor. Volc. in Flux Cor. Volc. in

  5. (EXP1) Near Surface Temperature Anomaly Correlation Coefficients YR 6-9 12-month average Full Init. Full Init. Anom. Init. Anom. Init. Climate trend in Flux Cor. Flux Cor. Climate trend out Full Init. Volc. in Full Init. Volc. in Flux Cor. Volc. in Flux Cor. Volc. in

  6. Grand Ensemble of all (EXP1) experiments - 27 Ensemble members Near Surface Temperature Anomaly Correlation Coefficients [Climate trend out] YR 2-5 12-month average YR 6-9 12-month average YR 2-5 12-month average YR 6-9 12-month average (EXP2) Near Surface Temperature Anomaly Correlation Coefficient [Climate trend out]

  7. Grand Ensemble of all (EXP1) experiments - 27 Ensemble members T2m YR 2-5 12-month average Cor=0.95, SPREAD/RMSE=0.63 YR 2-5 12-month average Cor=-0.01, Climate forcing out AMO index YR 2-5 12-month average Cor=0.78, SPREAD/RMSE=0.82 YR 2-5 12-month average Cor=0.9, Climate forcing out

  8. 1965-1995 Experiment 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) C1965 initial conditions, observed forcing from 1995 D1995 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).

  9. 1yr Running mean - Global SSTs 1995-2005 1965-1975 FOR FOR INI INI

  10. 1yr Running mean - Indian Ocean SSTs 1965-1975 1995-2005 FOR FOR INI INI

  11. 1yr Running mean - North Atlantic SSTs 1995-2005 1965-1975 FOR FOR INI INI

  12. SSTs: [1995-2005] - [1965-1975] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  13. SSTs: • [1995-1996] - [1965-1966] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  14. SSTs: [1995-1997] - [1965-1967] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  15. SSTs: • [1995-1998] - [1965-1968] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  16. SSTs: • [1995-1999] - [1965-1969] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  17. SSTs: • [1995-2000] - [1965-1970] Rianalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  18. SSTs: • [1995-2005] - [1965-1975] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  19. SSTs: • [1995-1996] - [1965-1966] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  20. SSTs: • [1995-1997] - [1965-1967] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  21. SSTs: • [1995-1998] - [1965-1968] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  22. SSTs: • [1995-1999] - [1965-1969] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  23. SSTs: • [1995-2000] - [1965-1970] Reanalysis Control Ctl95-FOR65 Ctl95-INI65 FOR95-Ctl65 INI95-Ctl65

  24. 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 1965-1995 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.

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