Shen Chunyan, Yan Yunrong, Zhao Hui, Pan Jiayi, T Devlin Adam
College of Fisheries, Guangdong Ocean University, Zhanjiang, China.
Center of South China Sea Fisheries Resources Monitoring and Assessment, Guangdong Ocean University, Zhanjiang, China.
PLoS One. 2018 Jan 12;13(1):e0191051. doi: 10.1371/journal.pone.0191051. eCollection 2018.
The influence of seasonal, monsoonal winds on the temporal and spatial variability of chlorophyll-a (chl-a) in the Beibu Gulf is studied based on long-term satellite data of sea surface winds, chl-a concentration and sea surface temperature (SST) and in-situ observations for the years from 2002 to 2014. The analysis results indicated that under northeasterly monsoonal winds, chl-a concentrations were substantially elevated in most area of the Beibu Gulf, with a high chl-a concentration (>2 mg m-3) patch extending southwestward from the coastal water of the northeastern Gulf, consistent with the winter wind pattern. Meanwhile, the spatial distribution of high chl-a concentration is correlated with low SST in the northeastern Gulf. In the southern Gulf, there was generally low chl-a, except in the coastal waters southwest of Hainan Island. Here, the upwelling cold water prevails outside the mouth of the Beibu Gulf, driven by the southwesterly monsoonal winds and the runoff from the Changhua River, as implied by low observed SST. Correlation analysis indicated the chl-a concentration was strongly modulated by wind speed (r = 0.63, p<0.001), particularly in the middle of the northern Gulf and southern Hainan Island (r>0.7, p<0.001). Integrated analysis also showed that stratification is weak and mixing is strong in winter as affected by the high wind speed, which suggests that the wind-induced mixing is a dominant mechanism for entrainment of nutrients and the spatial distribution of chl-a in winter.
基于2002年至2014年海面风、叶绿素a（chl-a）浓度和海表面温度（SST）的长期卫星数据以及现场观测资料，研究了季节性季风对北部湾叶绿素a（chl-a）时空变化的影响。分析结果表明，在东北季风作用下，北部湾大部分区域的chl-a浓度显著升高，一个高chl-a浓度（>2 mg m-3）斑块从北部湾东北部的近岸水域向西南延伸，这与冬季风型一致。同时，北部湾东北部高chl-a浓度的空间分布与低海表面温度相关。在北部湾南部，除海南岛西南部近岸水域外，chl-a含量普遍较低。在此，北部湾口外盛行上升流冷水，这是由西南季风和昌化江径流驱动的，低海表面温度观测结果也表明了这一点。相关分析表明，chl-a浓度受风速强烈调制（r = 0.63，p<0.001），特别是在北部湾中部和海南岛南部（r>0.7，p<0.001）。综合分析还表明，受高风速影响，冬季分层较弱而混合较强，这表明风致混合是冬季营养物质夹带和chl-a空间分布的主导机制。
