近65年ENSO事件强度变化及时频特征研究

INTENSITIES AND TIME-FREQUENCY VARIABILITY OF ENSO IN THE LAST 65 YEARS

利用海洋尼诺指数(ONI)、南方涛动指数(SOI)和多变量ENSO指数(MEI)等ENSO特征值分析了1951年1月—2016年5月近65年ENSO事件的强度与时频特征,并将其强度划分为5个等级。结果表明:近65年共发生22次暖事件(El Ni?o)和13次冷事件(La Ni?a);对ENSO特征值进行频次分析发现,强El Ni?o月份所占比例比强La Ni?a多;使用连续小波、交叉小波和小波相干分析得出,ENSO循环主要具有2~7 a的周期,还具有10~16 a的年代际变化。

Based on multiple E1 Nino-Southern Oscillation （ENSO） indices,Oceanic Nino index （ONI）, Southern Oscillation index （SOI）, Multivariate ENSO index （MEI）, etc. we classified the intensities of ENSO events into five levels, analyzed the intensities and time-frequency variability of ENSO events during the period 1951--2016. Over the last 65 years, there have been 22 warm events （El Nino） and 13 cold events （La Nina）. Frequency analysis is applied to the indexes of ENSO, which indicates that the percentage of strong warm events months is much more than that of strong cold events months. Three methods of time-frequency continuous wavelet analysis, cross wavelet analysis, wavelet coherency were used, and the results are in good agreement with the principal period （2~7-yr） and the interdecadal variability （10-16-yr） of ENSO cycle.