黄海冷水团季节性变化对悬浮泥沙输运的影响

Seasonal variation of the Yellow Sea cold water mass and its impact on suspended sediment transport

黄海冷水团是夏季黄海海域典型的水文现象,对区域的环流结构、物质输运和生态系统有重要影响。基于黄海海域不同季节的水文观测数据及悬浮体实测资料,结合HYCOM模型数据,研究黄海冷水团季节性变化对悬浮泥沙输运的影响。结果表明,黄海冷水团存在显著的季节性变化,春季开始形成,夏季最为发育,夏末秋初开始衰减,冬季消失。伴随着冷水团在秋冬季节的衰减,其水文结构也发生调整,表现为垂向温度梯度减弱,温跃层的深度由20 m增加至40 m,边界处的温度锋面由121°E向东移动至123°E。冷水团区域温跃层以及其边界处温度锋面的存在,限制了悬浮泥沙在垂向上跨跃层与水平方向上跨锋面的扩散与输运。黄海冷水团的季节性变化对悬浮泥沙输运产生了重要影响,导致近岸悬浮泥沙向东扩散范围增加,冷水团底部悬沙浓度增加。

The Yellow Sea Cold Water Mass(YSCWM)is a typical hydrological phenomenon in the Yellow Sea in summer,it has significant impacts on regional circulation system,material transport,and ecosystem.Based on the observation data of hydrological and suspended sediment concentration(SSC)in different seasons in the Yellow Sea,combined with HYCOM model data,the seasonal variations of the YSCWM and its impact on suspended sediment transport were investigated.The findings indicate notable seasonal variations in the YSCWM:emerging in spring,reaching its peak in summer,weakening from late summer to early autumn,and disappearing in winter.The hydrographic structure of the YSCWM also experiences adjustments as manifested by the reduction in vertical temperature gradient,the increase in thermocline depth from 20 m to 40m,and the movement of temperature front at boundary from 121°E to 123°E.The presence of thermocline and temperature fronts restricts the vertical diffusion and horizontal transport of suspended sediments across layers and fronts.These seasonal variations of the YSCWM lead to the expansion of the nearshore dispersion area of suspended sediments,the increase in SSC at the bottom of the YSCWM,and the decrease in SSC above the YSCWM.