Suspended Sediment Transport and Deposition due to Strong Regional Shear Current Front: an example from the shelf waters off eastern Shandong Peninsula
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摘要: 利用2007年国家908专项ST02区块（渤海海峡及北黄海）水体专项夏季和冬季两个航次调查的温度、浊度和悬浮体浓度数据，选取了跨越山东半岛东端外海泥质沉积体的B1和B2两个断面，结合该区浅地层剖面资料，辅以研究海域的冬季环流数值模拟，着重分析了山东半岛东端外海强海流切变锋作用下的悬浮体输送和沉积特征。结果表明山东半岛东端外海悬浮体向外海输送存在类似“夏储冬输”的规律：夏季，北黄海海水浊度普遍小，不仅北黄海温跃层抑制了底层悬浮体向中上层水体扩散，而且北黄海冷水团在中底层与山东半岛东部沿岸水也形成了显著的温度和悬浮体锋面，阻碍了悬浮物的纬向输送，故夏季应是悬浮体沉积的主要时节；冬季，温跃层消亡，在强风的作用下，山东半岛东部悬浮体浓度高且垂向混合较好，然而在泥质沉积体顶积层两侧，山东半岛东部沿岸中下层北上的逆风补偿流和北上的黄海暖流与位于顶积层上方表中层南下的沿岸流构成了两道显著的强海流切变锋，使得底积层上大量的再悬浮沉积物不能越过山东半岛东部陆架末梢，从而有助于形成山东半岛东端外海特有的Ω状泥质沉积体。Abstract: Based on field data of temperature, turbidity and suspended matter concentration in summer and winter derived from the project named National Coastal Sea Comprehensive Investigation and Evaluation (908ST02), the suspended sediment transport and deposition due to strong regional shear current front off eastern Shandong Peninsula were studied, combined with observation from B1 and B2 sections, circulation simulation in winter by POM model and shallow seismic profile. The results show that the transportation mechanism of suspended matter off eastern Shandong Peninsula is similar to the existing rule in East China Sea: deposition in summer and transport in winter. In summer, not only suspended matter was restricted near bottom by thermocline, but also restricted by the front formed by coastal currents off eastern Shandong Peninsula and northern Yellow Sea cold water mass. Therefore suspended matter mainly deposited in summer. In winter, with the help of strong northeastly wind and the thermocline, the turbidity was high vertical mixing was better off eastern Shandong Peninsula. However, two strong shear current fronts could be found on both sides of the topset of mud wedge, which was respectively generated by northward upwind compensation current along eastern Shandong Peninsula in the middle and lower water, northward Yellow Sea warm currents and southward coastal wind currents above topset of mud wedge. The two strong shear current fronts prevented suspended sediments from bottomset of the mud wedge getting cross eastern Shandong Peninsula continental shelf peripheral, which was helpful to omegashaped (‘Ω’) mud wedge formation off eastern Shandong Peninsula.
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Key words:
- suspended sediment /
- Yellow Sea cold water mass /
- yellow Sea warm current /
- muddy wedge /
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