A WESTERN PACIFIC OSCILLATOR PARADIGM FOR THE EL-NINO SOUTHERN OSCILLATION

A data-based hypothesis is presented on the mechanism of the El Nino-S outhern Oscillation (ENSO), a major determinant of interannual global climate variability; The hypothesis emphasizes the importance of off-e quator sea surface temperature and sea level pressure variations west of the dateline for initiating equatorial easterly winds over the far western Pacific. These winds compete with westerly winds over the equa torial central Pacific enabling the coupled ocean-atmosphere system to oscillate. Consistent with this hypothesis, an analogical oscillator model is constructed that produces ENSO-like oscillations. The propose d mechanism differs from the delayed oscillator paradigm in that wave reflection at the western boundary is not a necessary condition for th e coupled ocean-atmosphere system to oscillate.