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Study of current fluctuations based on satellite altimetry data

基于卫星测高数据的海流波动研究

基本信息

批准号：
63540313
负责人：
IMAWAKI Shiro
金额：
$ 1.02万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

Measuring sea-surface height by the radar altimeter on board satellite is a very promising technique; it covers almost all the world oceans, there are no data loss due to the presence of clouds, and surface velocities can be estimated directly from the sea-surface dynamic topography (here abbreviated SSDT) which could be derived from the altimetry data. However, the error of the estimated satellite orbit height is too large, so far, to use the data in geophysical studies. In the present study, we develop a procedure to reduce this error by using optimal interpolation technique, estimate the temporal mean and fluctuation of the SSDT using the latest geoid data, and compare the results with those from the conventional oceanographic observations. We select the study area in the western North Pacific, and use the altimetry data by satellite SEASAT for about three months (July-October, 1978).In 1988, we developed the analysis procedure for the altimetry data, and estimated the temporal mean SSDT. The estimated mean elevation field relative to the geoid qualitatively shows the existence of the Kuroshio in a limited local area. But for the whole of the study area, it can not be used to estimate the mean SSDT (the accuracy of the geoid data is not satisfactory).In 1989, we estimated the temporal fluctuation SSDT, and compared the results with observed fluctuations of the Kuroshio axis, movements of the warm and cold water masses off Tohoku, and sea level fluctuations at island stations around Japan. The results show that the temporal fluctuation of the SSDT estimated from the satellite altimetry data represents the actual long-term fluctuations of the sea level very well.

利用卫星雷达高度计测量海面高度是一项非常有前途的技术；它几乎覆盖了世界上所有的海洋，不会因云的存在而导致数据丢失，并且可以直接根据高度测量数据得出的海面动态地形（此处缩写为SSDT）来估计表面速度。然而，估计的卫星轨道高度误差太大，目前尚无法用于地球物理研究。在本研究中，我们开发了一种程序，通过使用最佳插值技术来减少这种误差，使用最新的大地水准面数据估计 SSDT 的时间平均值和波动，并将结果与传统海洋观测的结果进行比较。我们选择北太平洋西部的研究区域，使用SEASAT卫星约三个月（1978年7月至10月）的测高数据。1988年，我们开发了测高数据的分析程序，并估计了时间平均SSDT。相对于大地水准面的估计平均高程场定性地表明了有限局部区域内黑潮的存在。但对于整个研究区域来说，它不能用来估计平均SSDT（大地水准面数据的精度并不令人满意）。1989年，我们估计了时间波动SSDT，并将结果与观测到的黑潮轴波动、东北地区冷暖水团的运动以及日本周边岛屿站的海平面波动进行了比较。结果表明，根据卫星测高数据估计的SSDT的时间波动很好地代表了海平面的实际长期波动。