南海中西部叶绿素时空变化特征分析

Spatio-temporal distribution of chlorophyllin the mid-western South China Sea

本文使用2003年1月—2019年12月MODIS遥感数据,结合海表温度、风速分析南海中西部叶绿素质量浓度分布特征和影响因素。结果显示南海中西部叶绿素质量浓度分布存在时空变化。EOF分解表明,EOF1可能反映台风等极端天气对叶绿素的影响;而EOF2和EOF3均反映了夏季沿岸上升流对叶绿素分布的影响。相关分析表明南海中西部叶绿素质量浓度与海面风场呈正相关(r=0.87,p<0.01),与海表温度呈负相关(r=-0.59,p<0.05)。夏季在西南季风影响下越南东南沿海形成上升流,导致该区浮游植物旺发、叶绿素质量浓度升高;冬季受强东北季风影响,研究区海洋上层混合作用强烈,营养盐供应增加,促进了浮游植物生长,叶绿素质量浓度高于其他季节。

Using the MODIS remote sensing data from Jan.2003 to Dec.2019,and combining with the data of sea surface temperature(SST)and wind speed(WS),the chlorophyll concentrations distribution in the mid-western South China Sea and their controlling factors were discussed.The results showed the seasonal variations of the spatio-temporal distribution of chlorophyll concentration in the study area.EOF decomposition indicated that EOF1 probably reflected the impact of extreme weather such as typhoons on the concentration of chlorophyll,while EOF2 and EOF3 reflected influence of the coastal upwelling.The correlation analysis showed that the concentration of chlorophyll had good positive correlation with the WS(r=0.87,p<0.01),and negative correlation with SST(r=-0.59,p<0.05).In summer,the upwelling current formed along the southeastern coast of Vietnam under the influence of southwest monsoon,and it resulted in flourishing of phytoplankton and increase of chlorophyll concentration.In winter,the mixing of upper ocean layer became strong and the nutrient supply increased under the influence of strong northeast monsoon.It promoted the growth of phytoplankton and resulted in higher chlorophyll concentration than that in other seasons.