西北地区东部夏季温度特征及与热带SSTA的相关分析

A DIAGNOSIS FOR CHARACTERISTIC ON SUMMER TEMPERATURE IN THE EASTERN PART OF NORTHWEST CHINA AND ITS RELATION WITH SSTA OVER TROPICAL PACIFIC

本文利用１９５１－１９９７年我国西北地区东部１５个测站的地面气温资料和１９５０－１９９６年热带太平洋地区月平均海温资料，分析了西北地区东部夏季（６－８月）气温的空间分布特征和时间变化规律，以及热带太平洋各区域海温异常与西北地区东部气温变化之间的联系。分析结果表明：用ＥＯＦ分解得到的前三个主要特征向量（占总方差的８０％以上）基本反映了西北地区东部的气温变化特征，用这三个特征向量重建的气温距平场，存在着７年的主周期，它的信号最强。在１９９３年前后发生了由冷转暖的转变，热带太平洋的三个区域中，西太平洋暖池（Ｗｐｉ）（１４０°Ｅ－１８０°Ｅ，１０°Ｓ－１０°Ｎ）是影响西北地区东部气温变化的关键区，该区域前期冬季和春季的海温变化是预报酉北地区东部气温变化的强信号。

By using the data set of the surface air temperature of 15 stations in the eastern part of Northwest China during the period of 1951-1997 and monthly mean sea surface temperature (SST) in Pacific during 1950-1996,this paper analyses characteristic on spatial and temporal variability for summer temperature in the eastern part of Northwest China. A possible relationship between SST anomalies of regions in Pacific and the summer tempera- ture is also studied. The results show that the first three eigenvalues obtained by EOE analy- sis (above 80% of the total variance) can essentially explain the characteristic on the summer temperature anomalies in the eastern part of Northwest China. The temperature anomalies reconstructed by those three eigenvalues have two dominant scales on 7 years and around 20 years. Between them 7 years' oscillation is statistically significant at 95% level. On the decade scale,there appears a jump of the temperature from cooler to warmer around in 1993. Among three areas of tropical Pacific,the warm pool of tropical western Pacific (Wpi) (140° E-180°E, 10°S-10°N) is a key area that affects the summer temperature in the eastern part of Northwest China. The SST anomaly in last winter or last spring over that area is a strong signal that predicts the summer temperature variability.