COMPARATIVE ANALYSIS OF ATMOSPHERIC AND OCEANIC CONDITIONS BEFORE THE OCCURRENCE OF TWO TYPES OF EL NIO EVENTS
XU Shu-wen
ZHI Xie-fei
WANG Xiao-chun
Abstract：The atmospheric and oceanic conditions before the onset of EP El Nio and CP El Nio in nearly 30 years are compared and analyzed by using 850 hPa wind,20 ℃ isotherm depth,sea surface temperature and the Wheeler and Hendon index.The results are as follows:In the western equatorial Pacific,the occurrence of the anomalously strong westerly winds of the EP El Nio is earlier than that of the CP El Nio.Its intensity is far stronger than that of the CP El Nio.Two months before the El Nio,the anomaly westerly winds of the EP El Nio have extended to the east Pacific region.In contrast,the westerly wind anomaly of the CP El Nio can on-ly extend (develop)to the west of the dateline.Unlike the EP El Nio,the CP El Nio is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset.The thermocline depth anomaly of the EP El Nio can significantly move eastward and deepen.In addition,we also find that the evolution of ther-mocline is ahead of the development of the sea surface temperature for the EP El Nio.The strong MJO activity of the EP El Nio in the western and central Pacific is earlier than that of the CP El Nio.Measured by zonal wind square in the 30 ~60 d band,the intensity of MJO activity of the EP El Nio is significantly greater than that of the CP El Nio before the onset of El Nio.
Keywords：EP El Ni?oCP El Ni?oequatorial zonal windthermoclineMJO
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：10( 668-677 )