Impact of the Madden- Julian Oscillation on ENSO Michael Delman Advisor: Dr. Doug Sinton 12/8/05

The MJO The MJO dominates variability in the tropical Pacific The MJO dominates variability in the tropical Pacific Eastward propagating atmospheric Kelvin wave associated with enhanced convection Eastward propagating atmospheric Kelvin wave associated with enhanced convection –30-90 day period tracked by RMM (850mb zonal wind, 200mb zonal wind, and OLR) –Forces easterly migration of west Pacific warm pool –Modifies atmospheric circulation –Alters global precipitation patterns

ENSO Anomalous warming of eastern and central, tropical Pacific Ocean Anomalous warming of eastern and central, tropical Pacific Ocean Sea level pressure anomalies across the Pacific Sea level pressure anomalies across the Pacific –Tahiti and Darwin –Southern Oscillation Index (SOI) Trade Winds abate or reverse direction Trade Winds abate or reverse direction –Modifies atmospheric circulation –Alters global precipitation pattern

The Dilemma What causes: What causes: –West Pacific warm pool to move into eastern/central topical Pacific? –Sea level pressure anomalies at Tahiti and Darwin? (Fluctuations in the SOI) –Abatement of Trade Winds? Which of these ENSO factors triggers the others? …..Which comes first? Which of these ENSO factors triggers the others? …..Which comes first?

Possible Answer Does the MJO, through atmospheric and oceanic forcing, cause changes in the SOI? Does the MJO, through atmospheric and oceanic forcing, cause changes in the SOI? Methods of analysis: Methods of analysis: –Study a possible correlation between the RMM and the SOI –Use OLR, 850mb wind anomalies, and 200mb wind anomalies to correlate precise location of MJO to oceanic forcing (migration of warm waters) –Find lag between oceanic forcing and SLP changes