中文摘要：

利用WOD09和Argo剖面资料，结合SODA、OFES、GPCP和wHOI等资料分析了吕宋海峡西侧海域混合层盐度1984--2010年间的长期变化趋势和年代际变化特征，并利用混合层盐度平衡方程探讨了其变化机理。研究结果表明：（1）吕宋海峡西侧海域的盐度整体上呈现下降趋势，线性趋势为-0．020／a；（2）以1999年为界，吕宋海峡西侧海域的盐度在1999年之前为正距平，最大正距平值可达0．14，平均值为0．05，在1999年之后为负距平，最大负距平值为-0．22，平均值为-0．06；（3）影响该海域混合层盐度的长期变化趋势和年代际变化的主要因素为平流作用，特别是黑潮入侵的变化。

英文摘要：

Based on WOD09 and Argo data of twenty seven years（1984--2010）, and combined with SODA, OFES,GPCP and WHOI data, the long-term trends and interdecadal variability of mixed layer salinity at the western Luzon Strait were analyzed. The results can be described as follows. （1）the salinity decreased about --0. 020 per year from 1984 to 2010 （2）because of the variability of Kuroshio meridianal flux, the Kuroshio invasion was weakened after 1999, which resulted in the salinity being positive anomaly before 1999, with a maximum of 0.14 and a mean of 0.05, while negative anomaly after 1999, with a minimum of --0.22 and a mean of --0.06 （3）by calculating the salinity budget, the variability of salinity at the western Luzon Strait is controlled by advection primarily.