The study on the monitoring of oceanic condition in the East China Sea

本项研究的目的是利用近一个月的大调查区域的海洋学资料，估算短周期和小尺度变化分量，并利用海洋化学示踪剂阐明水团的流态系统和分布机制。主要研究结果如下：1.短周期和小空间尺度变化（1）通过在水深110 m的大陆架上进行的17次55小时的周期性调查，获得了包括营养盐等地球化学示踪物在内的水性质三维分布的潮汐周期变化。(2)By通过沿黑潮锋面附近的短线沿着约10天的多次观测，发现低盐度水向黑潮中层俯冲的时间尺度仅为几天。(3)By黑潮或陆架区同一测站间隔5 ~ 10天的观测发现，黑潮变化伴随着水性质的大幅度变化。2.水团的判别与跟踪（1）通过在陆架区和黑潮区进行的4次细站距大面积观测，我们得到了详细的三维水的属性和电流的分布。(2)We已经发现非保守材料，如颗粒有机物（碳和氮）、叶绿素、营养物和氧，以及通过荧光细胞计区分的三个微型浮游生物群落的每一个量，可用于区分水团并跟踪它们的运动作为指示剂。(3)We发现盐度和溶解氧略低于黑潮水的水团在外大陆架上占有相当大的面积。

The objectives of our research program are to estimate the shot-periods and small-scale variation components in the oceanographic data obtained during about one-month long cruise in wide survey area, and to elucidate the current system and distribution mechanism of water mass by using the biogeoche-mical tracers. The major results are as follows.1. Short-periods and small-spatial scale variations (1)By the 17 cyclic surveys for 55 hours running around 3 points ca 15 km apart over the continental shelf of 110 m depth, we have obtained the tidal period variations of 3-D distributions of water properties including biogeochemical tracers (nutrients etc.). (2)By the surveys repeated several times during about 10 days along short lines crossing the Kuroshio front near the continental shelf break, we have found the time scale of low salinity water subduction into the middle layer of Kuroshio Water to be only a few days. (3)By the surveys 5 to 10 days apart at same stations in the Kuroshio or continental shelf region, we have found the large variation of water properties to be accompanied with the variation of Kuroshio.2.Discrimination and tracking of water masses (1)By the four wide area surveys with fine station spacing over the continental shelf and the Kuroshio regions, we have obtained the detailed 3-D distributions of water properties and currents. (2)We have found the non-conservative materials such as particulate organic matter (carbon and nitrogen), chlorophyll, nutrients, and oxygen, and each amount of three communities of picoplankton discriminated by fluocytometer to be utilized in the discrimination of water masses and tracking their movements as the indicators. (3)We have found that the water mass of which salinity and dissolved oxygen are slightly lower than the Kuroshio Water, occupies the rather wide area over the outer continental shelf.