The wavelet analysis of Sea Level change in China Sea during 1992-2006

More than 14 yr of merged altimetry Sea Level Anomalies (SLA) data were used to analyze the signature characters of sea level changes. The result shows that the annual signal plays a dominant role in the sea level changes of China Sea. Then, semiannual periodic signal in the South China Sea also shows strong, while semiannual 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 plus/minus 0.49) mm/a, (4.61 plus/minus 0.35) mm/a and (3.