热带海表温度和低层风场的年际变率及与ENSO循环的相关特征研究

采用 NCEP/NCAR的 1 979～ 1 998年逐月平均的海表温度及 1 0 0 0 h Pa风场资料 ,进行滤波和均方差计算 ,得到了热带太平洋、印度洋、大西洋海表温度 (SST)和风场的年际变化特征。用旋转主分量 (RPC)方法和投影法对热带三大洋海表温度距平 (SSTA)进行分析 ,得到了各大洋 SSTA演变的主要时空特征和相应的距平风场特征 ;并用相关分析研究热带三大洋与ENSO相关的特征 ,得到三大洋间的同期相关关系为 :印度洋 SSTA与赤道东太平洋 SSTA成正相关 ,而赤道东大西洋 SSTA与赤道东太平洋 SSTA成弱的负相关 ;赤道印度洋在落后于赤道东太平洋 3个月左右时正相关达到最大 ,赤道大西洋在超前于赤道东太平洋 6个月左右时负相关达到最大 ;热带印度洋和大西洋与 ENSO相关的分量对各自大洋海表温度年际变化的方差贡献数值相近 ,最大在 40 %以上 ,平均解释方差分别为 1 4%和 1 2 %。

THE INTERANNUAL VARIABILITY OF SEA SURFACE TEMPERATURE AND SURFACE WIND FIELD IN THE TROPICAL OCEANS AND THE CORRE-LATION WITH THE ENSO CYCLE

Utilizing the NCEP/NCAR reanalysis monthly data, and using filter and mean variance calculation, the interannual variability in sea surface temperature (SST) and 1000hPa wind field for the Pacific, Indian, and Atlantic Oceans is investigated for 20 years (1979-1998). The characters of time-space evolution in sea surface temperature anomaly (SSTA) for each ocean and corresponding wind anomaly field are attained using rotated principal component and projection analysis methods. Using the method of correlation analysis, the characters of three tropical oceans correlated with ENSO are investigated. The contemporary correlation between the SSTA in the Indian Ocean and the SSTA in the equatorial east Pacific is positive, and there is a weak anticorrelation between the SSTA in the equatorial east Atlantic Ocean and the SSTA in the equatorial east Pacific. The SSTA in the equatorial Indian Ocean lags by 3 months the dominant Pacific ENSO mode, and the SSTA in the equatorial Atlantic Ocean leads by 6 months the dominant Pacific ENSO mode when the positive correlation and the anticorrelation reach to the most. The component correlated with ENSO in tropical Indian Ocean and tropical Atlantic Ocean display much the same amount of total variance in each ocean i.e., 14% in the Indian Oceans and 12% in the Atlantic Ocean and the maximum is all above 40%.