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Study on the Subduction of Low Salinity Water into the Intermediate Layer of the Kuroshio in the East China Sea

东海低盐度水俯冲到黑潮中层的研究

基本信息

批准号：
11640433
负责人：
MATSUNO Takeshi
金额：
$ 2.3万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640433/
关键词：
Low salinity water Kuroshio front Subduction Internal waves 黒潮前線渦

项目摘要

Vertical profiles of temperature, salinity and current velocity were obtained along a cross-stream section around the shelf break in the East China Sea in May 1999, October 1999, May 2000 and October 2000. Temporal variations of temperature and velocity were also obtained with mooring arrays.During the observation in May 1999, low salinity water tended to extend offshore and subduct into the intermediate layer of the Kuroshio. However, origin of the subducted low salinity water was not clear. In October 1999, low salinity water in the shelf area appears to be entrained into the eddy around the Kuroshio front, while subduction of low salinity water cannot be seen clearly. In May 2000, two research vessels were deployed simultaneously and temperature and salinity maps were obtained repeatedly along two sections across the Kuroshio. Along the section downstream of the Kuroshio, temperature front was moved onshore accompanied with distinct subduction of low salinity water during the first half of the observation period. On the other hand, significant cross-shelf migration of the front and distinct subduction of low salinity water cannot be seen along the section upstream of the Kuroshio. This fact suggests that the spatial variability of subduction should be very large. In October 2000, observations were carried out over rather wide area in the southern East China Sea, and some signals of low salinity water subduction were found along a few sections.Short time scale internal waves were observed with mooring current meters. Particularly, distinct development of internal waves were found during the observation in May 1999 and it seems to make the stratification change locally. Vertically detailed structure of current velocity was obtained in the observation of May 2000. Cross-shelf current with a small vertical scale was found accompanied with a change of stratification, while offshore current corresponding to low salinity water subduction was not detected.

1999年5月、1999年10月、2000年5月和2000年10月，在东海陆架坡折附近的一个横流断面上采集了沿着温、盐和流速的垂直剖面资料。在1999年5月的观测中，低盐度海水有向外海延伸并潜入黑潮中层的趋势。然而，俯冲低盐度水的来源尚不清楚。1999年10月，陆架区的低盐度水似乎被卷入黑潮锋面周围的涡旋，而低盐度水的俯冲则看不清楚。2000年5月，两艘研究船同时部署，沿黑潮的沿着两个断面反复获得温度和盐度图。在观测期间的前半段，温度锋沿着黑潮下游断面向岸上移动，并伴有明显的低盐水俯冲。另一方面，沿沿着黑潮上游断面未观察到锋面明显的跨陆架迁移和明显的低盐度水俯冲。这一事实表明，俯冲的空间变异性应该是非常大的。2000年10月在东海南部进行了大范围的观测，发现沿着部分断面存在低盐度水俯冲的信号，并在系泊海流计上观测到短时间尺度内波。特别是1999年5月的观测中发现了明显的内波发展，似乎使局部层结发生了变化。在2000年5月的观测中获得了流速的垂向详细结构。在层结变化的同时，发现了垂直尺度较小的跨陆架流，而没有发现与低盐度水俯冲作用相对应的离岸流。