台湾海峡表层叶绿素含量的季节、年际变化特征研究

Seasonal and interannual variability of the chlorophyll concentration in the surface ocean of the Taiwan Strait

本文通过分析SeaWiFS海洋水色卫星提供的叶绿素资料,给出了台湾海峡表层叶绿素含量空间分布季节变化的完整图像.台湾海峡表层叶绿素含量的季节变化明显.海峡北部呈显著的春、秋“双峰”分布,而海峡南部则以夏、秋“双峰”结构为主.叶绿素含量高值主要位于福建省近岸海域,海峡西侧高于海峡东侧.此外,叶绿素含量的分布存在两个局地高值区,一个位于台湾浅滩附近,另一个位于台湾岛西北淡水河口以外海域.福建省近岸海域及台湾岛西北淡水河口附近的叶绿素含量高值区与地表径流携带较多的营养物质入海密切相关;而台湾浅滩附近的叶绿素含量高值受季节变异的海洋锋调制.进一步的分析表明,台湾海峡区域平均的叶绿素含量不仅具有周期约81 d和101 d的季节内振荡信号,还具有与ENSO指数呈显著负相关(-0.28)的周期约3 a的年际振荡信号.此外,台湾海峡区域平均的叶绿素含量具有逐年递增的长期演化趋势,速率达0.036 mg/(m3.a).

Using the chlorophyll data from SeaWiFS, a full view of the seasonal variations of the chlorophyll concentration in the surface sea of the Taiwan Strait is presented. The chlorophyll concentration shows a ＂double-peaks＂ pattern in the northern Taiwan Strait in spring and autumn. They appeared mainly in the southern Taiwan Strait in summer and autumn. The high chlorophyll concentration is located in sea adjacent to Fujian besides, local features of the high chlorophyll concentration are detected in the Taiwan Bank and the estuary zone northwest of the Taiwan Island. The chlorophyll abundant in the sea adjacent to the Fujian and the estuary zone northwest of the Taiwan Island is presumed to be linked with large amounts of nutrients in the sea due to river transportation. While the high chlorophyll concentration around the Taiwan Bank should have been controlled by the oceanic fronts. Except for the intraseasonal oscillations （81 d and 101 d）, the chlorophyll concentration has also apparent interannual oscillation signal （3 a） which correlates significantly with the ENSO index （ - 0.28 ）. Further analysis shows that the region-averaged chlorophyll concentration increases gradually at the rate of 0.036 mg/（m^3 ·a）.