Evaluating the Spring-Neap Tidal Effects on Chlorophyll-a Variations Based on the Geostationary Satellite
Evaluating the Spring-Neap Tidal Effects on Chlorophyll-a Variations Based on the Geostationary Satellite
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DOI：
10.3389/fmars.2021.758538
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
Qinwang Xing;Huaming Yu;Haiqing Yu;Hui Wang;S. Ito;C. Yuan
中科院分区：
文献类型：
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作者：
Qinwang Xing;Huaming Yu;Haiqing Yu;Hui Wang;S. Ito;C. Yuan
潮汐是大多数大陆架海域的主要水动力过程，已被证明对海洋生态系统动力学和海洋地球化学循环具有重大影响。现场观测和卫星观测表明，在一些陆架沃茨，春小潮导致叶绿素a浓度（Chl-a）以两周为周期的波动。然而，卫星观测的叶绿素a中大量的缺失值和低观测频率已被认为是调查区域模式的主要障碍，该模式显示了春小潮对叶绿素a的影响以及在相对较大的区域内影响的季节变化。以Himawari-8为例，提出了一种适用于地球同步卫星的简单算法，旨在获得与潮汐相关的每日气候Chl-a数据集（TDCD），并定量估计春小潮对Chl-a变化的影响。利用TDCD获得的叶绿素a时间序列，在某些特定的近岸沃茨，尤其是东海、孟加拉湾、南海和澳大利亚北方沃茨，发现了叶绿素a双周波动的显著信号和高贡献率，并对叶绿素a双周波动具有较高的解释力。结果表明，大潮-小潮能引起近岸海域叶绿素a的半周波动，其年变幅为平均值的12-33%。在温带大陆架区，叶绿素a的双周波动的显着的季节变化，而在热带沃茨的水平保持相对稳定。进一步分析表明，Chl-a每两周的时空波动与大、小潮的潮流差异密切相关。潮流差异的季节性变化被认为是温带大陆架地区春-小潮对叶绿素a影响的季节性波动的一个关键驱动因素。该研究有助于更好地理解与潮汐相关的海洋生态系统动力学和海洋地球化学循环，并有助于改进物理-海洋地球化学模型。
Tides are the dominant hydrodynamic processes in most continental shelf seas and have been proven to have a significant impact on both marine ecosystem dynamics and biogeochemical cycles. In situ and satellite observations have suggested that the spring-neap tide results in fluctuations of chlorophyll-a concentrations (Chl-a) with a fortnightly period in some shelf waters. However, a large number of missing values and low observation frequency in satellite-observed Chl-a have been recognized as the major obstacle to investigating the regional pattern showing where and to what extent of the effects of spring-neap tide on Chl-a and the seasonal variations in the effects within a relatively large region. Taking Himawari-8 as an example, a simple algorithm appropriate for geostationary satellites was proposed in this study with the purpose of obtaining a tide-related daily climatological Chl-a dataset (TDCD) and to quantitatively estimate the effects of the spring-neap tide on Chl-a variations. Based on the Chl-a time series from TDCD, significant fortnightly signals of Chl-a fluctuations and high contribution together with high explanations of the fortnightly fluctuations for Chl-a variations were found in some specific inshore waters, especially in the East China Sea, Bay of Bengal, South China Sea, and northern Australian waters. The spring-neap tide was found able to induce the spatio-temporal fortnightly fluctuations of Chl-a with an annual amplitude of 12–33% of the mean in these inshore areas. Significant seasonal variations in the fortnightly fluctuation of Chl-a were observed in the temperate continental shelf regions, while levels remained relatively stable in the tropical waters. Further analysis implied that the spatio-temporal fortnightly fluctuations of Chl-a were closely associated with the tidal current differences between the spring and neap tides. Seasonal variations in the tidal current differences were found to be a key driving factor for seasonal fluctuations of the spring-neap tidal effects on Chl-a in the temperate continental shelf regions. This study provides a better understanding of tide-related marine ecosystem dynamics and biogeochemical cycles and is helpful in improving physical–biogeochemical models.