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Analyzing MJO-ENSO Interactions: State Dependence, Predictability, and Future Directions

This discussion addresses key issues surrounding the interactions between the MJO (Madden-Julian Oscillation) and ENSO (El Niño Southern Oscillation), focusing on the state dependence of WWBs (Westerly Wind Bursts) and their impact on predictability. Topics cover how the state dependence influences ENSO's seasonal evolution, recent changes in WWB-ENSO interactions, and the challenges faced by CGCMs (Coupled General Circulation Models) in simulating MJO dynamics. We also propose future research directions, including diagnostic studies and coordinated experiments to enhance understanding and predictions.

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Analyzing MJO-ENSO Interactions: State Dependence, Predictability, and Future Directions

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  1. MJO-ENSO interactions Discussion items

  2. Slingo’s strawman, revisited ????

  3. State dependence of WWBs From Eisenman What physical mechanisms determine the state-dependence of WWBs? What effect does the state-dependence have on ENSO predictability? What effect does the state-dependence have on the seasonal evolution of ENSO?

  4. Why did the WWB-ENSO interaction increase? WWB-ENSO interaction increased during the last 50 years from Jin et al. 2007

  5. Why are CGCMs doing such a poor job in simulating the MJO? What basic process is misrepresented? What effect does the state-dependence have on the seasonal evolution of ENSO?

  6. Precipitation spectra in Demeter Lin et al. Space-time spectrum of 15N-15S symmetric component of precipitation divided by the background spectrum

  7. But progress is happening … 3.5km resolution From Satoh, NICAM model From GFDL

  8. But progress is happening … Lag Correlation between Noise Variance and ENSO indices NCEP/NCAR Coupled control simulation SNU Coupled control simulation SNU with Cumulus momentum transfer (CMT) CMT mixes down westerly momentum Intensifies noise variance probably by Rossby wave instability Courtesy of Kug, 2007

  9. Key issues • Do we have to really go to ultrahigh resolution or are the present CGCM just out of tune for MJO? • Can we empirically correct for MJO deficiencies in ENSO prediction models? • What determines the state-dependence of MJO activity? • How does the under-representation of MJO in CGCMs affect ENSO and its predictability? • Why did WWB activity change during the last 30 years? • What observational data are needed to further unlock the MJO puzzle? • How can NPOCE help?

  10. Key issues • How stable is the ENSO-WWB relationship? • How does it affect ENSO predictability? • How well is the ENSO-WWB coupling representing in state-of-the art CGCMs and prediction models? • How does the ENSO-WWB coupling depend on the climate background state? • How does the seasonal cycle of WWBs affect the spring barrier of ENSO predictions?

  11. Coordinated experiments and diagnostics • Careful diagnostics of MJO processes in GCMs and CGCMs • Coordinated experiments with cumulus momentum transfer • Run CGCMs with diurnal cycle, coupling time step of two hours • Study change of atmospheric spectra due to ENSO

  12. Plan • Write a review paper on MJO-ENSO interactions (authors needed, more discussion in Pacific panel meeting)

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