中国近海1992～1998海平面变化监测与分析

The 1992～1998 Sea Level Anomalies in China Seas from Topex/Poseidon and ERS-1 Satellite Altimeter Data

利用 Topex/ Poseidon和 ERS-1卫星测高资料采用“共线”法计算出 1992 -10～ 1998-0 6中国近海海域海平面及其变化。在扣除 T/ P卫星测高仪的零点漂移影响后 ,发现与全球海平面上升率 (+ 2 .1± 1.3) mm/ a相比 ,不同海域的海平面变化趋势大不相同 ,黄、东、南海的海平面年变化率分别为 :(+ 3.44± 0 .6 1) mm/ a,(+ 3.12± 0 .47) mm/ a,(-1.41± 0 .48) mm/ a。从海平面变化异常中可以看出 1993,1994,1997～ 1998年 3次 El Nino异常对中国近海海域海平面的影响是南海海域最大 ,东海次之 ,黄海最小。除了对海平面进行传统的频谱分析外 ,还进行了多分辨率的小波分析 ,还发现在上述 3个海域中除了年周期变化较为稳定外 ,半年及季节 (10 0 d)周期项存在着时间漂移。此外 ,在上述 3个海域还存在着明显的两个月 (6 2 d)周期的变化 。

The collinear method is used to determine mean sea surface heights and their variations in the regions of China Seas including Yellow Sea,East China Sea and South China Sea with Topex/Poseidon and ERS-1 altimeter data during the period from October of 1992 to June of 1997.After having done the corrections of T/P altimeter instrument bias,and geophysical environment corrections of tide,ionosphere,wet and dry troposphere,sea-state bias and inverse barometry,we find that rising rates vary in different regions.Compared with global annual sea level rising rate (+2.1±1.3)mm/a,the annual rising rate in Yellow Sea,East China Sea and South China Sea is (+3.44±0.61)mm/a,(+3.12±0.47)mm/a,and (-1.41±0.48)mm/a,respectively.From sea level anomalies,it can be seen clearly that the influences of El Nino in 1993,1994,and 1997-1998 are greatest in South China Sea,less in East China Sea and least in Yellow Sea.Besides normal FFT spectrum analysis,a new wavelet analysis of WAPS was also used to sea level anomalies.The results show that annual period is stationary in each region of interest,but semi-annual and seasonal periods have some degree of period drift.In addition,we find there is an approximate two-month period in each region,and its mechanism is explored.