我国近海1992～2006年海平面变化的小波分析

The Wavelet Analysis of Sea Level Change in China Sea during 1992～2006

用14年多的多颗测高卫星同化海面异常数据,分析我国近海海平面信号变化特征,结果显示年周期信号在我国海域海平面变化中占有主导地位。其次,半年周期信号在南海也有较强显示,而黄海和东海则表示为高频信号,半年起伏及高频信号的周期和振幅均不稳定。首次在南海和东海海域发现存在一周期为准540 d的信号,其物理机制尚不明确。用标准Morlet小波变换方法对上述周期信号进行了提取。验潮站数据也证实了该信号的存在。海面异常分析结果显示在1993-2007年期间,我国海平面平均升高速率：黄海为（4.01±0.49）mm/a,东海为（4.61±0.35）mm/a,南海为（3.68±0.41）mm/a。海平面上升趋势地理分布结果显示海平面变化具有很大的空间差异性。

More than 14 yr of merged altimetry Sea Level Anomalies （SLA） data were used to analyze the signa ture characters of sea level changes. The result shows that the annual signal plays a dominant role in the sea lev el changes of China Sea. Then, scmiannual periodic signal in the South China Sea also shows strong, while semi annual periodic signal and other high-frequency signal with instability shows in the Yellow China Sea and East China Sea. More important, the period of quasi 540 d of the signal is also identified in the South China Sea, its physical mechanism is not clear. In this paper, the annual signal in China Seas, semiannual and quasi 540 d periodic signals in South China Sea are extracted using Morlet wavelet transform method. The tide gauge data were also used to prove the existence of this signal. Result of sea level variations in the China Sea shows that the sea level rises in the Yellow China Sea, East China Sea and South China Sea are （4.01±0.40） mm/a, （4.61±0.35） mm/a and （3.68±0.41） mm/a respectively. The geographical distribution result indicates that the sea level rise trends in China Sea present large differcnce in the spatial scale.