TOPEX/POSEIDON高度计浅海潮汐混淆的初步分析

A preliminary analysis of shallow water tidal aliasing inTOPEX/POSEIDON altimetric data

根据对卫星轨道特征和观测结果的分析，对TOPEX／POSEIDON（简称T／P）星载高度计在我国近海的潮致混淆现象进行了初步研究．分析表明，在浅海区T／P高度计的观测结果存在很强的潮致高频混淆．NASA分发的地球物理记录中所提供的潮汐订正值虽适用于大洋，但不能有效地除去浅海潮汐．虽然如此，T／P潮致混淆的主要频段的周期小于90d，因而可以通过滤波方法提取周期较长的海面高度季节信号，从而用于季节环流（如南海季风环流）的研究．采用FFT／IFFT方法滤波试验的结果显示，T／P的海面高度观测结果有很高的精度，滤波处理后的海面高度距平变化和地面潮位观测结果一致性良好，上、下行轨道交叉处相邻测点间的标准偏差在3cm左右，可满足南海环流研究的需要．

Aliased tidal errors in TOPEX/POSEIDON (T/P) altimetric data were studied based on analyses of satellite orbit features and observations in China's near seas. The results show that in shallow waters strong tidal aliasing occurs in observations ofT/P altimeter. Although the tidal correction provided in NASA's Geophysical Data Records works quite well for deep ocean basins,it can not effectively remove shallow water tides. However, since the main aliased tidal periods of T/P are shorter than 90 d, onecan extract the longer seasonal signal of sea surface height through filtering procedure. The filtered results can then be used to studyseasonal circulation (e. g., the monsoon driven circulation in the South China Sea). Results of several filtering experiments using aFFT/IFFT filter show that T/P altimeter measurement is quite accurate. The deviations of filtered sea surface height consist verywell with ground observation fronl tide gauges. The standard deviation between sea surface height observed by ascending and descending orbits near a cross-over point is about 3 cm, which will satisfy demands of the South China Sea circulation studies.