基于卫星漂流浮标轨迹的东海边界交换估算方法研究

A method for estimating boundary exchanges in the East China Sea based on satellite drifter trajectories

东海陆架斜坡和台湾海峡是我国东部近海从大洋和南海获取热量、盐量和营养盐的两个主要边界。本文建立了一个不规则分布漂流浮标轨迹的网格化处理方法和跨边界交换估算方法。该方法得到的漂流浮标轨迹累计次数再现了黑潮主轴位置并表明主轴两侧浮标存在显著的跨陆坡交换现象。浮标轨迹的统计结果揭示了东海陆坡上水体交换具有显著的区域性,即陆坡上存在7个主要交换区,3个交换区以入流为主,另4个交换区以出流为主。研究也表明跨东海陆坡交换具有明显的季节变化特征,秋季交换最剧烈且入流最显著,春季最弱。穿越台湾海峡的交换主要以北向入流为主,海峡东侧的交换更加明显,一年之中夏季最显著,春、冬季最弱。

The shelf slope and the Taiwan Strait are two main boundaries of the East China Sea,which obtain considerable heat and salinity as well as nutrients from the northwestern Pacific and the South China Sea. In this paper,based on the satellite drifter trajectories,a reliable method is established for estimating the cross-boundary exchanges by mapping the irregularly-distributed trajectories to the regular homogeneous grid. With this method,the calculated density of trajectories reveals the location of the Kuroshio main axis,and further indicates significant crossslope exchanges. The statistical results reveal the remarkable region feature of water exchanges along the shelf slope of the East China Sea,showing seven dynamic exchange zones,i. e.,three inflow（ shoreward） zones and four outflow（offshore） zones. The study also shows that the cross-slope exchange has prominent seasonality. The most significant exchange and the most distinctive inflow occurs in autumn while the weakest in spring. The exchange through the Taiwan Strait is mainly northward and the most intense exchange occurs in the eastern side of the strait. The exchange through the Taiwan Strait reaches the strongest in summer but the weakest in spring and in winter.