Based on analysis of the meridional winds over oceanic areas and sea surface temperature for 1950—1979 extracted from the data sets of COADS, the long-term variability of the meridional winds over the equatorial Indian–Pacific Oceans and its relationship to the onset and development of El Nino events have been studied. The major results are as follow: ① There is a great similarity between Intertropical Convergence Zone (ITCZ) over the Pacific and SST in the seasonal trend, with ITCZ and high SST found in Southern Hemisphere in winter and in Northern Hemisphere in summer. During El Nino years, unusual meridional winds were often observed, with significant convergence of meridinal wind occurring over near-equatorial regions. ② For the near-equatorial meridional winds, there are types of interannual low-frequency oscillations—QBO, SO, FYO. QBO plays an important role in the unusual behavior of meriodional wind for El Nino years, while SO is very important for both El-Nino and cold water years. These two oscillations may fit well to the observed variation in the meridional wind. FYO may enhance the variation of mericional wind. ③ Interannual low–frequency oscillations of meridional winds originate in the Indian Ocean—Maritime Continent and coastal area of the east Pacific. Unusual activities of winter monsoon in both hemispheres and trade wind off the coastal area of the east pacific are believed to the their major cause. ④ Monsoon-trade interaction shows up in the significant amplification of the disturbances of meridional wind while they propagate eastward form monsoon area to trade wind area
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