内潮对吕宋海峡地转流动力计算的影响

The Influence of Internal Tide on the Diagnostic Calculation of Geostrophic Current in Luzon Strait

利用2008年8~9月份吕宋海峡121°E断面上19.5°N^21°N之间4个连续站的CTD资料,讨论了内潮引起的温、盐剖面扰动对地转流诊断计算的影响,指出:在吕宋海峡,内潮引起的温、盐剖面扰动对地转流诊断计算的干扰不可忽略。因此,地转流诊断计算必须剔除温、盐剖面中的"内潮噪声"。另外,本文根据4个连续站时间平均后的温、盐剖面,通过动力计算法得到了吕宋海峡121°E断面上的地转流场,得出结论如下:吕宋海峡地转流速度较大部分多位于350 m以浅,流速最大值出现在表层;黑潮入侵南海主要发生于19.8°N^21°N的上层;在19.5°N^21°N之间,50~1 700 m深度范围内,海水体积通量呈现"上进下出"的垂向结构,350 m以浅为入流,流量约为2.6 Sv(1 Sv=1×106m3.s-1),350 m以深为出流,流量约为3.1 Sv。同期观测所得121°E断面上的盐度分布验证了本文所得地转流场的合理性。

On the basis of CTD data obtained on 4 repeat-observed stations located at 121°E, 19.5°N -21°N in the Luzon Strait of the cruise in the summer of 2008, the role of disturbances caused by internal tides in temperature and salinity profiles in calculating of the geostrophic currents is discussed. The result shows that the role of disturbances caused by internal tides in temperature and salinity profiles in calculat ing of the geostrophic currents is significant. When we use hydrographic data to calculate the geostrophic currents we have to take measures to remove the disturbances caused by internal tides in temperature and salinity profiles, unless there would be great errors. By using the time-averaged CTD data, the geo- strophic currents in the Luzon Strait is calculated. The result reveals that the significant part of the geo- strophic currents appear above 350 m. Kuroshio intrusion mainly happens between 19.5°N and 21°N, especially at the upper layer. Between 19.5°N and 21°N, the water volume transport shows a ＂flowing in at upper layer and flowing out at deeper layer＂ vertical structure, above 350 m the transport is westward （2. 6 Sv） and below 350 m it is eastward（3.1 Sv）. The distribution of the geostrophic currents we get is confirmed by the salinity distribution along 121°E Section.