庆良间水道的水交换对东海黑潮水团特性的影响

庆良间水道水交换对其上下游东海黑潮的流量和水团特性的变异都起到了非常重要的作用,本文通过将历史观测的WOD资料插值为1/8°×1/8°的网格化数据,估算了庆良间水道的地转流通量特征,然后结合Argo浮标数据讨论了庆良间水道的水交换对东海黑潮水团特性的影响,研究结果表明:(1)西太平洋通过庆良间水道流入东海冲绳海槽主要发生在水道的次表层,并且次表层的入侵可能跟庆良间水道东部的琉球流有关;(2)庆良间水道上下游黑潮的水团特性由于受到来自庆良间水道的动力混合作用导致其存在差异。黑潮次表层高盐水到达冲绳附近之后盐度略微增加,深度略微变浅,然而黑潮中层低盐水的盐度显著减小,深度明显加深;(3)庆良间水道上下游东海黑潮的次表层高盐水和中层低盐水其盐度的季节变化规律不一致。次表层高盐水盐度的季节变化可能同时受到庆良间水道的流量和表层淡水通量的影响,在冬季最强,夏季最弱,然而中层低盐水盐度的季节变化主要受庆良间水道流量的影响,在秋季最强,夏季最弱。

WATER EXCHANGE VIA THE KERAMA GAP AFFECTS SALINITY OF THE KUROSHIO

By interpolating the historical World Ocean Database (WOD) into 1/8° ×1/8°, we estimated the geostrophic flux of the Kerama Gap and analyzed the water exchange through the gap by combing with the Argo data, and discussed its impact on water property of the Kuroshio. The major results are as follows. (1) The Pacific water flows into the East China Sea (ECS) through the Kerama Gap in mainly a subsurface layer, which may be contributed by the eastern Ryukyu Currents. (2) The water mass characteristics of Kuroshio upstream and downstream have a significant variation. The salinity of Kuroshio subsurface water increases slightly at a shallower depth, but the salinity of Kuroshio intermediate water decreases remarkably at a much deeper layer. (3) The seasonal variation in salinity of subsurface and intermediate layers between the upstream and downstream is inconsistent i.e., the variation is the strongest in winter and weakest in summer in a subsurface layer, which may be affected by the Kerama Gap transport and surface freshwater flux, while for an intermediate layer, the variation is the strongest in autumn and weakest in summer, which is induced mainly by the variation of Kerama Gap transport.