南海东北部海域次表层水与中层水之流径

1992年春季以及1994年夏季，台湾海峡两岸曾同时出动多艘研究船在南海东北部海域协力执行了两次较大区域的水文调查作业。根据温盐曲线之类聚情形，发现盐温变率比（即温盐曲线斜率之倒数）是除了盐度极大值与盐度极小值外另一个简单又好用的温盐特征参数。此值乍视之下仅与温盐曲线之形状有关，但因其隐涵了时间的效应，故可有效反映出水团之变性程度，对分析、推断水团之流径甚有助益。经分析、对比温盐参数与动力高度之水平分布，发现1992年春季观测时之地转流场与温盐参数二者趋势不甚一致，但1994年夏季之测情却有很好的共通性，似乎表示后者之流况系处于稳定状态，因此观测现象应较具代表性。资料亦显示：不论春、夏，在吕宋岛西北角与东沙群岛之间的广大海域主要是受成群的气旋型环流所控制，此气旋群之范围因季节而异，夏季时其势力较向东、向北扩展，因而在巴士海峡、巴林塘海峡阻挡住黑潮区之外洋次表层与中层水团向西伸展，但外洋水团仍可在台湾岛南端逸入南海东北部，然后被南海内部流系辗转带往南海腹地。春季时，外洋水团虽可占据气旋群环流场东北方之台湾西南外海，但并未见能长驱直入南海内部者，仅有部分经变性后之外洋水被气旋群西侧之环流带往南海中部，表示逸入过程是南海与西菲律

ON THE TRAJECTORY OF SUBSURFACE AND INTERMEDIATE WATERS IN THE NORTHEASTERN SOUTH CHINA SEA

The exchange of water masses between the Western Philippine Sea (WPS) and the South China Sea (SCS) had long been an appealing topic for the study of the latter it is Well-known that saline waters have to be furnished by the former to the latt er, but the details are still obscure. During the spring of 1992 and summer of 1994, two systematically-arranged, larger-scale CTD surveys had been conducted by using multiple researeh vesses from both sides of the Taiwan Strait respectively; the data sets are instructive in illuminating some of foregoing obscurities. Along with contouring the spatial distribution of the maximum and minimum salinity, that of the shape paramete, dS / dT i.e. the reciprocal of the slope of a temperature / salinity curve in a Certain density range, has been made too. Numerical calcuations evidence that the latter parameter could well-depict the degree of evolution of water masses due to vertical diffusion. From them we found, the flow pattern was likely in changing during the spring survey, but is quasi-steady during the summer cruise, so that the data set of the latter is more repmtative. Additionally,the region in between Dongsha Islands and the northwes of Luzon is alwnys occupied by cyclonic systems. In summer, the systems could block the westward intrusion of Kuroshio waters at the Luzon Strait; waters from the WPS could be entrained into the SCS only at the northem reach of the Luzon Strait, then follow the cyconic flows moving southwestward into the interior of the SCS. In spring (and winter), though the WPS waters intrude into the area northeast of the cyconic system also southwest of Taiwan, no evidenas show that there exists a Kuroshio branch curent conveying the WPS waters swiftly into the interior of the SCS, indicating that the exchange of waters between the WPS and SCS has to rely on entrainment process too.