MAINTENANCE MECHANISM OF THE KUROSHIO FRONT

这个为期两年的项目的目的是阐明海洋锋的维持机制，这是重要的在沿海一侧的Kurosio。研究了长江口海区海流的时空变化。1992年10月至12月，在屋久岛西南50 km × 20 km处，用高频海面雷达每两小时测量一次。利用屋久岛9月1日至12月31日的逐日气象资料，12月24日NOAA/AVHRR卫星红外热像，利用9月1日至12月31日期间每隔两天在鹿儿岛和那霸之间运行的渡船测量的海表温度的时间变化，从长期和大范围的角度考察了高频雷达观测期的外部条件尺度变化根据1992年11月17日至23日的海面水平辐合区和垂直涡度分量的分布及其时间变化，发现水平辐合区的空间分布受潮流影响较大，辐合带和辐散带沿黑潮北方边缘沿着交替分布，空间尺度为2 ~ 6 km。25小时的平均辐合达到1.5 × 10^<-4>s^<-1>。当锋面向南移动时，水平辐散占主导地位，反之亦然。观测结果证实了锋面涡对黑潮锋的维持起着重要作用，并发现辐合带并不沿黑潮沿着存在，而是辐合带和辐散带交替分布。

The objective of this two-year period project is to elucidate the maintenance mechanism of the oceanic front which is significant in the coastal side of the Kurosio. The spatial and temporal variation of current in the area of ca. 50 km x 20 km southwest of the Yakushima Island was measured by HF ocean surface radar every two hours during three mnonths from October to December of 1992. The daily meteorological data at the Yakushima Island from september 1 to December 31, the satellite infrared thermal image on December 24 obtained by NOAA/AVHRR, and temporal change of sea surface temperature measured by ferry liner running between Kagoshima and Naha every two days from September 1 to December 31 were utilized for examining the external conditions of the HF radar observation period in the long term and large scale variation. From the distributions of horizontal convergence and vertical component of vorticity at the sea surface and their temporal change from 17 to 23 of November, 1992, it was found that while the spatial distribution of horizontal convergence zone is largely affected by tidal current, convergence zone and divergence zone distribute alternatively to each other along the northern edge of the Kuroshio with spatial scale of 2 - 6 km. The 25-hour mean of convergence reaches up to 1.5 x 10^<-4> s^<-1>. The horizontal divergence dominates when the front is moving towards south and vice versa. It was confirmed by our observation that the frontal eddy plays an important role in the maintenance of the Kuroshio front, and found that the convergence zone does not exist as a long and narrow band along the Kuroshio, but convergence and divergence zones distribute alternatively to each other.