A MULTI-STATISTICAL ANALYSIS OF THE SOUTHERN OSCILLATION (SO) AND ITS RELATION TO THE MEAN MONTHLY ATMOSPHERIC CIRCULATION AT 500 hPa IN THE NORTHERN HEMISPHERE

<正> In this paper the correlation analysis, factor analysis, fuzzy classification, and principal component analysis (PCA) are performed for the southern oscillation index (SOI) from the Climate Analysis Center (CAC) at the NOAA. It is shown that the 12-month SOI can be classified into two groups: one from January through April and the other from May through December. They differ in persistency and correlation. It is also found that the year of strong or weak SO can be defined by the first principal component of the SOI. The 11 years of weak SO thus defined contain 9 El Nino events.In addition, the relations between the SOI and 500 hPa geopotential height, mean monthly zonal height, mean monthly interzonal height differences, centers of atmospheric activities, characteristics of the atmospheric circulation (the intensity index of the north polar vortex, the area index of the subtropical West Pacific high, mean monthly zonal and meridional circulation indexes in Asia and Eurasia) in the period of 24 months fr