热带太平洋海平面高度年变化与季节内变化特征

ANNUAL AND INTRASEASONAL VARIATIONS IN SEA SURFACE HEIGHT OVER THE TROPICAL PACIFIC

利用小波分析方法 ,对热带太平洋 ( 30°S— 30°N ,1 30°E— 80°W ) 1 992年 1 0月 3日—1 996年 1 0月 9日期间的海平面高度资料从振荡周期、强度和传播等方面进行了全面分析。研究结果表明 ,海平面高度存在明显的年变化、5 8— 1 39天振荡和 2 9— 35天振荡。其中年变化主要存在于 0°— 1 5°N、1 35°E— 95°W ,传播不明显。 5 8- 1 39天振荡主要位于以 2 0°N和 2 0°S为中心的两个副热带区域中 (范围约为 1 6°N— 30°N、1 30°E— 1 5 0°W和 1 7°S— 30°S、1 5 0°E—1 5 0°W) ,它们向西传播 ,传播速度随纬度增高而变慢 ,在 2 0°N传播速度约为 1 0cm/s,波长约为80 0km。 90天左右的振荡具有年变化且与ElNi no事件有很好的对应关系。 2 9— 35天振荡主要存在于中东太平洋以 5°N和 5°S为中心的带状区域中 ,经度范围约为 1 60°W— 1 0 5°W和1 70°W— 1 40°W ,传播不明显。年变化、5 8— 1 39天和 2 9— 35天振荡方差占总方差的百分比分别约为 :2 0 %— 40 %、1 0 %和 1 %— 2 %。

On the basis of wavelet theory,comprehensive analysis of the data of sea surface height(TOPEX/Posidon data)in the tropical Pacific(30°S-30°N,130°E-80°W),focusing on oscillation period,strength and propagation,is undertaken The main results obtained are as follows (1) Distinct variations with periods of one year,58-139 days and 29-35 days exist in the surface height data (2) Annual variation in the Northern Hemisphere locates in 0°N-15°N,with longitudinal extension of 170°E-90°W in 0°N-5°N and 130°E-90°W in 5°N-15°N,whereas in the Southern Hemisphere a narrow band extending from 0°N,175°E to 30°S,100°W can be seen Oscillation of 58-139 day periods is remarked in 16°N-30°N,130°E-155°W and 17°S-30°S,150°E- 150°W, where there are two subtropical regions with central latitude of 20°N and 20°S,respectively 29-35 day variations are found in two bands in the central and eastern Pacific centered by 5°N and 5°S,ranging from 160°W to 105°W and from 170°W to 140°W,respectively (3) Oscillation of 58-139 day periods propagates westward,with speed decreasing with latitude The speed of propagation and the wavelength are around 10cm/s and 800km,respectively Annual variations and oscillations of 29-35 days have no obvious propagation features (4) Oscillation of 90 days period or so reveals annual variability and has a good correlation with ENSO (5) The ratios of variances for period of one year,58-139 days and 29-35 days to total variance are about 20%-40%,10% and 1%-2%,respectively.