25th Conference on Hurricanes and Tropical Meteorology


Variability of MJO Associated with ENSO and the QBO

John D. Sheaffer, Colorado State Univ., Fort Collins, CO

Variability of the MJO, as expressed by the amplitude of 30-60 day oscillations of surface pressure values in the tropical west Pacific, is examined for long-term trends and sensitivity to broad scale climate features including the QBO and ENSO, among others. QBU stratified data (ie., 30-60 day power) show a robust tendency for sharply stronger amplitudes for November through February during the east phase and for a March through May maximum during the west phase. ENSO stratified oscillations show robust El Nino linked enhancements concentrated in 45-60 day frequencies during September to November whereas La Nina data tend to become stronger in 30-45 day frequencies during December to March. The QBO linked variations are consistent with the effects of previously suggested mechanisms for QBO-troposphere interactions whereas the ENSO linked differences, though robust in time at any location, show a more complex spatial variability.

Session 17B, Intraseasonal Variability III (Parallel with Sessions 17A and 17C)
Friday, 3 May 2002, 11:00 AM-12:30 PM

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