20世纪70年代前后北太平洋海温场气候特征的比较

Comparison of the Climatic Characters of North Pacific SST between for-and aft-1970s

采用 195 0— 1998年 5 88个月的海表温度 SST(Sea Surface Temperature)资料 ,应用 EOF、小波分析等方法 ,分析了北太平洋海温时空分布特征 ,指出 2 0世纪 70年代中后期北太平洋海温有明显变化 :赤道中东太平洋由冷转暖 ,中高纬西风漂流区由暖转冷 ,且西风漂流区变化更为显著。厄尔尼诺和拉尼娜事件在此前后也呈现出不同的特征 :1976年前拉尼娜 (1976年后厄尔尼诺 )事件持续时间长 ,强度大 ,事件发展初期厄尔尼诺海区就表现为较强的负 (正 )距平。海温变化存在 2～ 6 a的 ENSO循环周期 ,并迭加着 8～ 9a的年际振荡和 2 2 a左右的年代际尺度的变化。另外 ,还有以1981年前后为转折点的长期变化信号。

EOF,wavelet analysis,composite analysis and t test are used to investigate the SST of 1950-1998(588 months),and describe spatial and temporal characters of the SST.It is found that there is an apparent transition during middle and later 1970s:eastern and middle Equatorial Pacific SST turns higher,and mid latitude Pacific SST turns lower,even more distinctly in west wind drift zone.It is also found that the duration of El Nino(La Nina) is longer with greater intensity after(before) 1976 than before(after) the time,La Nina zone has positive(negative) SSTA in the early stage;the course of SST has an ENSO cycle of 2～6 years with annual oscillation of 8～9 years,a interdecadal variation scale of about 22 years and a signal for long term change,the turn being in 1981.