1995与1996年夏季琉球群岛两侧海流
The circulation on the both sides of the Ryukyu Islands during the summer of 1995 and 1996
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摘要: 基于1995,1996年夏季日本调查船的观测资料,采用P矢量方法对琉球群岛两侧的海流进行了计算.结果表明:黑潮为琉球群岛以西海域的一支东北向强流,1996年夏季的流速比1995年夏季的强,在深层出现南向逆流.黑潮东、西两侧分别存在一个反气旋式暖涡和一个弱的气旋式冷涡.1995年夏季,琉球群岛以东,从表层至以下层都存在一支沿岸北上的海流,即琉球海流.该海流来自黑潮分支,为本海区的一个主要物理特征.琉球海流以下出现弱的南向流.冲绳岛以东海域,在25°～25°30'N,128°30'～129°10'E附近从表层至700m水深存在一个中尺度的反气旋式暖涡.在温、盐水平分布图上,对应的出现一个较高温、低密水块.1996年夏季,冲绳岛西南海域存在一个中尺度的反气旋式暖涡和一个气旋式冷涡,形成一个偶极子,中间为较强的南向流,该现象为本海区的一个重要物理特征,属首次报道.冲绳岛以东表层主要被南向流控制,琉球海流不明显.200m以深在近岸出现北向流,这表明琉球海流的核心位于次表层.琉球海流的下面出现南向流.计算海区东北部从表层到700m水深出现一个中尺度的反气旋式暖涡,与1995年夏季时比较,其位置向北移动.此外在1996年夏季从近表层到深层,垂直方向和水平方向上的等温线、等盐线波动很大,例如在C断面上冷、暖涡相间出现,且暖
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关键词:
- 琉球群岛两侧海流 /
- 1995与1996年夏季海流 /
- P矢量方法
Abstract: Based on the CTD data obtained by the R/V Chofu Maru in summer cruise of 1995 and the R/V Yoko-Maru in summer cruise of 1996,respectively,the currents on the both sides of the Ryukyu Islands are calculated by the P-vector inverse method.The calculated results for two summer cruises of 1995 and 1996 show that:(1) A maximum velocity of the Kuroshio is about 115 cm/s in the summer of 1996,which is greater than that in the summer of 1995.The Kuroshio in the summer of 1996 is stronger than that in the summer of 1995.(2) In the summer of 1995 there is a northeastward current(the Ryukyu Current) east of the Ryukyu Islands.A weaker southwest-ward countercurrent exists under the Ryukyu Current.There is a meso-scale anticyclonic eddy east of the Ryukyu Current,which is a warm water from the surface to the lower layer.This warm eddy is located at 25°～25°30'N,128°30'～129°10'E,and its average speed is about 15 cm/s.(3) In the summer of 1996 a south ward current appears in the surface layer east of the Ryukyu Islands while the Ryukyu Current doesn't appear obviously.The Ryukyu Current exists in the layer below of 200 m level.Its corelies in the subsurface layer,and its maximum velocity is about 14 cm/s at 300 m level.A south ward current also exists under the Ryukyu Current.There is also an anticyclonic warmeddy east of the Ryukyu Current.Its position moves northward in the summer of 1996 than that in the summer of 1996.In the region southeast of the Okinawa Island there are an anticyclonic warm and a cyclonic cold eddies,respectively.These two eddies compose adipole,which is discovered first in this region.There is a southward current between the above two eddies with the maximum velocity of 36 cm/s at the surface. -
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