The triggering effect of near-equatorial cyclones on El Niño

The relationship between tropical cyclones developing in the Northwest Pacific and El Niño is analysed and the triggering mechanism of the near-equatorial cyclones on El Niño is proposed. It is pointed out that the near-equatorial tropical cyclones developing equatorward of l0°N can intensify equatorial westerlies and produce Kelvin waves, which propagate to the South American Coasts in about 2–3 months, inducing SST to rise there. The near-equatoral cyclones play an essential role in El Niño. The beginning period of El Niño ranges from January to May. The number of near-equatorial cyclones developing in this period determines whether El Niño can be generated or not. The persistence period is from June to September. El Niño can not continue developing unless there are adequate near-equatorial cyclones. If there are not, the developed El Niño will be broken down. The period from October to December is called the developing period. During this period El Niño may approach its culmination only when adequate near-eqatorial cyclones have been developed east of 140°E, especially east of 160°E.