A review of 2005/2006 ENSO Predictions Tony Barnston Lisa Goddard Shuhua Li

1. A review of 2005/2006 ENSO Predictions Tony Barnston Lisa Goddard Shuhua Li International Research Institute for Climate and Society (IRI)

2. Two Events of Interest: A brief La Nina(*), and a “new” El Nino (*) * * * * * * * * *La Nina, Dec-Mar ’05-06 *El Nino, October ‘06

4. Last week’s SST anomaly | | | | | | | | | | | --------------------------------------------------------------------

6. Renewed, east-extended westerly wind anomalies

7. mid-Oct ‘06

8. ** *

9. * * Climate Prediction Center NCEP

10. From Climate Diagnostics Center, Boulder, Colorado Black: This year * *

11. The onset of La Nina conditions in December 2005, after a largely ENSO-neutral northern autumn, was unprecedented since 1950. How did it emerge?

12. Precursor to Brief La Nina Conditions in late 2005 Sep 2005 Colombia ← ← ← e q u a t o r------------ ← ← L Peru ← H H 110W Note: Vern Kousky says this anticyclone is spurious, due to Reanalysis biases.

13. Precursor to Brief La Nina Conditions in late 2005 Oct 2005 Colombia ← ← e q u a t o r------------ ← H Peru H H 110W Note: Vern Kousky says this anticyclone is spurious, due to Reanalysis biases.

14. Precursor to Brief La Nina Conditions in late 2005 Nov 2005 Colombia ← e q u a t o r------------ H H H Peru H L 110W Note: Vern Kousky says this anticyclone is spurious, due to Reanalysis biases.

15. Mid-2005 to Mid-2006: Brief La Nina Conditions Five-Day Zonal Wind, SST, and 20º Isotherm Depth Anomalies along Equator Zonal Wind SST 20º Isotherm Depth * *

16. How did statistical and dynamical ENSO prediction models fare regarding the brief 2005-06 La Nina conditions and the late 2006 El Nino development?

17. Cool Conditions Coming

18. Cool Conditions Coming

19. Cool Conditions Coming

20. El Nino Conditions Coming

21. El Nino Conditions Coming

22. El Nino Conditions Coming

23. .

24. . -----------------------------------------------------------------------------

25. . ----------------------------------------------------------------------------- Unanticipated by stat models

26. . --------------------------------------------------------------- . --------------------------------------------------------------- Unanticipated by stat models

27. Blue asterisk* means the model did comparatively well during this period. Hybrid Models: Dynamical ocean, statistical atmosphere * .

28. Blue asterisk* means the model did comparatively well during this period. Abbreviated dynamical coupled models .

29. Blue asterisk* means the model did comparatively well during this period. * Fully comprehensive coupled models: Run in the U.S. * .

30. Blue asterisk* means the model did comparatively well during this period. * Fully comprehensive coupled models: Run outside of U.S. * * .

31. Blue asterisk* means the model did comparatively well during this period. Statistical models based on the redness of the coupled system * .

32. Blue asterisk* means the model did comparatively well during this period. Statistical models based on linear or nonlinear regression * .

33. Blue asterisk* means the model did comparatively well during this period. Statistical models based on unique designs (regression to construct an analog, neurological network). * * .

34. The following graphs show how each model did in predicting the ENSO state from JFM 2006 to ASO 2007, by one-month increments (so there are up to 18 3-month periods), for lead times of 1 to 5 months (1 month lead is really “zero lead”, such as a forecast for JFM made from December [or even earlier] initial conditions). Scores: Correlation (uncentered; means not removed) RMSE Skill score: ( 1 – [RMSEmodel/RMSEclim] ) The blue curve shows the model skill. The pink curve shows the skill of persistence from the most recently observed one month SST.

35. (blue line) persistence

36. (blue line) * persistence *

37. (blue line) persistence

38. (blue line) persistence

39. (blue line) persistence

40. (blue line) * persistence *

41. (blue line) * persistence *

42. (blue line) persistence

43. (blue line) * persistence

44. (blue line) * persistence *

45. (blue line) * persistence *

46. (blue line) persistence

47. (blue line) persistence

48. (blue line) * persistence *

49. (blue line) persistence

50. (blue line) persistence