The Kuroshio Large Meander (LM) is known to be highly aperiodic and can last from 1 to 10 years. Since a stationary cold core formed between the Kuroshio and the southern coast of Japan off Enshu-Nada and approaching warm saltier water on the eastern side of the LM changes the local environment drastically, many commercially valuable fish species distribute differently from the non-LM period, impacting local fisheries. Despite this importance of the LM, the influences of the LM on the low trophic levels such as phytoplankton and zooplankton have still been unclear. In this study, satellite daily sea surface chlorophyll data are analyzed in relation to the LM. The results show positive anomalies of the chlorophyll-a concentration along the Kuroshio path during the LM periods, 2004-2005 and 2017-2019, from the upstream off Shikoku to the downstream (140oE). These positive anomalies are started by the triggering meander generated off south of Kyushu, which then slowly propagates to the downstream LM region in both the LM periods. Even though the detailed patterns along the Kuroshio region in the two LM periods were different, similar formations of the positive anomalies on the western side of the LM with shallower mixed layer depth are observed. Furthermore, we found clear relationships between the minimum distance from several stations along the coast to the Kuroshio axis and the mean chlorophyll-a anomaly, with significant correlations with the distance from different stations.

中文翻译：

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由于大曲流，沿黑潮的浮游植物增加

众所周知，黑潮大河曲 (LM) 是高度非周期性的，可以持续 1 到 10 年。由于在黑潮和远州滩附近的日本南部海岸之间形成了一个静止的冷核，并在 LM 东侧接近温暖的咸水，极大地改变了当地的环境，许多具有商业价值的鱼类物种的分布与非 LM 时期不同，影响当地渔业。尽管 LM 如此重要，但 LM 对浮游植物和浮游动物等低营养级的影响仍不清楚。在这项研究中，卫星每日海面叶绿素数据与 LM 相关进行了分析。结果显示，2004-2005年和2017-2019年LM期间，沿黑潮路径叶绿素-a浓度呈正异常，从四国的上游到下游 (140oE)。这些正异常是由九州以南产生的触发曲流开始的，然后在两个 LM 时期缓慢传播到下游的 LM 区域。尽管两个LM时期沿黑潮地区的详细模式不同，但在LM西侧观察到相似的正异常形成，混合层深度较浅。此外，我们发现沿海岸的几个站点到黑潮轴的最小距离与平均叶绿素-a异常之间存在明显的关系，并且与不同站点的距离具有显着相关性。然后在两个 LM 周期中缓慢传播到下游的 LM 区域。尽管两个LM时期沿黑潮地区的详细模式不同，但在LM西侧观察到相似的正异常形成，混合层深度较浅。此外，我们发现沿海岸的几个站点到黑潮轴的最小距离与平均叶绿素-a异常之间存在明显的关系，并且与不同站点的距离具有显着相关性。然后在两个 LM 周期中缓慢传播到下游的 LM 区域。尽管两个LM时期沿黑潮地区的详细模式不同，但在LM西侧观察到相似的正异常形成，混合层深度较浅。此外，我们发现沿海岸的几个站点到黑潮轴的最小距离与平均叶绿素-a异常之间存在明显的关系，并且与不同站点的距离具有显着相关性。