吕宋岛西侧中、深层环流的诊断分析

Diagnostic analysis of circulation in the intermediate and deepocean in the west of Luzon Island

利用P矢量方法和第3版本的美国海军全球数字环境模式(GDEM)气候态月平均温、盐数据诊断分析了南海吕宋岛西侧中层与深层环流结构。结果显示在南海吕宋岛西侧中层存在一个反气旋涡,与前人在此处深层发现的气旋涡相反,且2个涡旋均与低盐中心位置相对应。诊断结果还表明中层反气旋涡从上到下流速逐渐减弱,深层气旋涡则随深度逐渐加强,在两涡旋之间的过渡层流速非常弱。中层反气旋涡的平均流速大小和低盐中心的平均盐度存在明显的季节变化,5—7月最强,这可能是中层环流在一定程度上受上层环流影响的表现。

Using the data from the 3th version of U.S.Navy Generalized Digital Environment Model （GDEM）,we diagnosed the intermediate circulation and deep circulation in the west of Luzon Island with the P-vector method.The diagnosed result shows that it is an anticyclonic circulation in the west of Luzon Island in the intermediate layer （1 000～2 000 m vertical-averaged）,different from the deep layer circulation （2 400 m to bottom vertical-averaged） in the same region,which has been reported as cyclone in the previous studies.These two eddies both correspond with the low salinity water in geographical location.The results further show that the velocity of anticyclonic circulation reduces as the depth increases,and the velocity of cyclonic circulation is stronger in the deeper layer.The current at the depletion layer （about 2 200 m） is weak and disorder.Further research demonstrates that low salinity water and anticyclonic circulation in the intermediate layer have distinct seasonal variation,they both become stronger in May to July,which may suggests that the anticyclonic circulation is influenced by the upper layer circulation to some degree.