太平洋—印度洋海温与我国东部旱涝型年代际变化的关系

对我国东部各区域的夏季降水的正交小波分解表明,其大于28年的分量可以很好地表示华北和长江中下游地区在20世纪70年代前后旱涝相反的年代际变化特征。合成分析表明,北太平洋、热带印度洋海温和东亚高空急流与我国东部夏季旱涝型的年代际变化密切相关。东亚高空急流和西太平洋副热带高压在70年代前后的年代际差异对旱涝型发生年代际变化起到重要作用;北太平洋和热带印度洋海温的年代际变化近百年来是协同一致的,二者有可能共同对旱涝型的变化产生影响。进一步分析指出,北太平洋—热带印度洋海温的变化与急流和副高的南北位置在年际和年代际尺度上都密切相关。可见,北太平洋-热带印度洋海表温度异常(SSTA)对于我国东部旱型涝的年代际变化确实具有重要的预示作用。

Relationship between Interdecadal Variation of North Pacific-Equatorial Indian Ocean SST and Transition of Rainfall Pattern in East China around the 1970s

Orthogonal wavelet analysis of summer rainfall in East China showed its opposite spatial pattern before and after the 1970s,mainly the opposite situation of precipitation in North China and in the middle and lower reaches of the Yangtze River.The difference of meridional position of the summer East Asian upper-tropospheric Jet Stream(EAJS) and West Pacific Subtropical High(WPSH) before and after the 1970s was one of the most important reasons for the transition of summer rainfall pattern.Besides,on interdecadal time scales,North Pacific and Tropical Indian Ocean Sea Surface Temperature Anomaly(SSTA) variated coherently,and were closely related to the transition of summer rainfall pattern in East China.What's more,North Pacific-Equatorial Indian Ocean Sea Surface Temperatures(SST)showed a certain relationship with the north-south movement of EAJS and WPSH on both interannual and interdecadal time scales.Thus,North Pacific-Equatorial Indian Ocean SST was indeed an important factor for the prediction of summer rainfall pattern in East China.