Tropical Pacific decadal oscillation driven by the interaction between ENSO and mean state

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Tropical Pacific decadal oscillation driven by
the interaction between ENSO and mean state

• Jung Choi and Soon-Il An
• Climate Theory Lab., Yonsei Univ.,
• Seoul, Korea

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Outline

• Introduction
• 2. Correlation between
• ENSO amplitude and
  mean state
• 3. ENSO ? mean state
• 4. Mean state ? ENSO
• 5. Conclusion

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! Decadal modulation of ENSO

• Observation
• - The ENSO is the strongest signal of
  interannual variability in the climate system.
• - There are evidences of the decadal
  modulations of the frequency and amplitude of
  ENSO.

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NINO Index
Decadal modulation
Q) What is the origin of the decadal
oscillations???
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Mid-latitude
Teleconnection
Tropical Pacific
ENSO
Decadal Change(mean state)
Annual Cycle MJO
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! Background

• Observation
• The late 1970s climate shift (mean state
  change)
• ? ENSO (Amplitude and
  Period change)
• Nonlinear rectification
• Asymmetry of ENSO (El Nino gt La Nina)
• 
  ? mean state change
• The mechanisms responsible for the ENSO
  modulation as coupled phenomenon are not well
  understood.

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Damp down ENSO
ENSO unstable regime
Increasing of Stability
Cooling SST in E. Pacific
Increasing asymmetry and amplitude of ENSO
Shoaling H in E. Pacific
Deepening H in E. Pacific
Warming SST in E. Pacific
Decreasing asymmetry and amplitude of ENSO
Sustain ENSO
Reduction of Stability
ENSO stable regime
lt Schematic diagram for TPDO gt