RELATIONSHIP BETWEEN PROCEEDING PACIFIC SEA SURFACE TEMPERATURE AND SUBTROPICAL HIGH INDEXES OF MAIN RAINING SEASONS

With correlation analysis and factor analysis methods,the effects of proceeding Pacific SST on subtropical high indexes of main raining seasons are discussed. The results of correlation analysis show that the effects of SST on subtropical high indexes differ in seasons and regions. SST variation mostly affects the area and intensity indexes of the subtropical high,followed by western ridge index,and the effect on the ridge line index is more remarkable than on the north boundary index. From the ability of SST in fitting the whole set of five subtropical high indexes,it is known that the effect is better in autumn and winter than in spring. It is also found that the effect of SST in the area of central and eastern equatorial Pacific and west coast of North America is better than the one in north-west Pacific area. The results of factor analysis revealed that the first proceeding common factor of SST of each season reflected mainly the inverse relation of SST variation between the central and eastern part of equatorial Pacific and the western Pacific,which correlate better with the subtropical high indexes in the main raining seasons than other common factors of SST. The analysis of interdecadal variation indicated that the variation of SST was conducive to the emergence of the La Ni?a event before the end of 1970s,so in the summer the subtropical high is likely to be weaker and smaller and located eastward and northward. After the 1980s,this case bears just the opposite characteristics.