1. Dynamics of ENSO Complexity and Sensitivity
F-F Jin
University of Hawaii
Review: ENSO Regimes :
Multiplicity & Criticality
ENSO Multiplicity and Two NINO Indices
ENSO Criticality and Amplitude Perspective
9/20/2018

2. Review of ENSO regimes:
Multiplicity & Criticality
9/20/2018

3. Westward propagating before 76, eastward or standing after 76
ENSO regime changed !
9/20/2018

4. ENSO Regime & Multiplicity
Multiple regimes for coupled modes: Jin et al 1993
Coupling
SST- mode
Mixed-mode
Time scale
(RO)
TH- mode
9/20/2018

5. S- mode Jin et al 1993
TH- mode Jin et al 1993
9/20/2018

6. ENSO Regime & Multiplicity
Multiple regimes for coupled modes: Jin et al 1993
SST- mode
TH- mode
Mixed-mode
Time scale
Coupling
S-T & T-S    modes
with
D2-singularity
Mean depth
( Jin et al 1993, 97, Bejarano and Jin 2008)
Mean wind
9/20/2018

7. Periods ENSO Regime remapped from Jin and Neelin 1993 byFedorov and
Phliander 2001
Growth rates
9/20/2018

8. 2008 Eigen-value changes of ZC model following different
intensities of the climatological wind from 80% to 120%
Merging of
QQ and QB
Bejarano and Jin
2008
9/20/2018

9. Regimes for two ENSO-like modes
9/20/2018

10. Noise is only a part of story.
The fundamental underlying properties for ENSO complexity are multiplicity and near criticality under current climate conditions.
Noise is only a part of story.
9/20/2018

11. Observational Indication of ENSO Multiplicity and Two Simple NINO Indices for WP & CT ENSO
9/20/2018

12. Regime with multiple types of ENSO mode Yeh (2009)
9/20/2018

13. Scatter plots for N3 and N4 indices (a), and for NCT and NWP indices (b), where the green, red, blue and black denote WP El Niño, CT El Niño, La Niña and near neutral states, respectively. CORs denote correlations between two indices in each panel.
9/20/2018 13

14. Time series of N3 (grey) and NCT (black) indices in (a), and those of N4 (grey) and NWP (black) indices in (b). Grey lines indicate one standard deviation of NCT and NWP indices. CORs denote correlations between two curves in each panel.
9/20/2018 14

15. SST anomaly patterns regressed onto normalized NWP index (a), NCT index (b), N4 (c), and composite maps of the CP El Niño (d), WP El Niño (e), and La Niña (f) corresponding to the red, green, blue in Fig. 1, respectively.
9/20/2018 15

16. Lead-lag correlations between NCT and NWP indices using a 15-yr running window in (a), and the blue (red) curve in (b) indicating average during months when NCT (NWP) index leads.
9/20/2018 16

17. ENSO Multiplicity -->Different flavors of ENSO
WP and CT indices, based on Nino3 and NINO4, are useful indices for capturing different flavors and regime changes of ENSO.
9/20/2018

18. (iii) ENSO criticality: Amplitude Theory
9/20/2018

19. How do we diagnose each terms?or
How do we diagnose each terms?
9/20/2018

20. ENSO growth rate: Bjerknes Instability index (Jin et al 2007)
A & B: dynamic and thermodynamic damping
C, D, E: three positive feedbacks, each depending on three factors:
(i) The natures of the basic state,
(ii) The sensitivity of the atmospheric surface wind responses to SSTA
in the ENSO region.
(iii) The sensitivity of the oceanic responses to surface winds.
* A new method for obtaining BJ index is under the development.
9/20/2018

21. The blue curves represent nonlinear fits following the theoretical formula for ENSO variance as the function of the BJ indexes.
9/20/2018

22. ENSO regime changes due to GW?
(iv) Perspectives
ENSO regime changes due to GW?
9/20/2018

23. Perspective (cont.)
The fundamental mechanism for ENSO complexity is the co-existences of different types of ENSO and different regimes (Multiplicity and Near Criticality) in the neighborhood of current climate conditions.
Much research works are need to advance our our understanding of ENSO complexity and its implications.
ENSO regimes due to Multiplicity and Near Criticality indicating Structure instability, if
so, single best model does not exist, MME
becomes necessity.
9/20/2018

24. …?
9/20/2018

25. What do we know?
ENSO comprises irregular, partially seasonal phase-locked and somewhat warm skewed interannual climate fluctuations originated from tropic Pacific ocean-atmosphere system with various global impacts.
ENSO is related to coupled modes: Bjerknes positive feedbacks for growth, ocean dynamic mass adjustment for phase transition.
Noises are important.
ENSO can be predicted with skill at about 1-year lead (for now).
9/20/2018

26. What controls regimes of ENSO?
Why ENSO are so different now from a few decade ago? Why ENSO is so sensitive to changes in climate state?
What controls regimes of ENSO?
How does ENSO respond to global warming? …
How does ENSO regime influence ENSO predictability?
How does ENSO regime influence ENSO’s interaction ?
with annual cycle and other modes of climate variability etc. ? …
9/20/2018

27. Figure. Scatter plots of the BJ index versus ENSO amplitude from (a) control runs and (b) CO2 runs. Colored circles represent the coupled models. ENSO amplitude is defined as the variance of SST anomalies averaged over the NINO3.4.
9/20/2018

28. Validation of BJ index formulism (Jin et al 2007)
9/20/2018