浅海底边界动力过程与物质交换研究

Study on Bottom Boundary Layer Processes and Water-sediment Exchange

浅海底边界动力过程是能量分配、颗粒物输运和水—底边界物质交换的关键环节,深入研究浅海底边界动力过程是提高环境容纳量预测能力的重要前提。分析了国内外该研究方向的进展和现状,提出在黄海中部和长江口外两个典型海区,以集成先进设备的海床基观测平台和水体要素连续观测的研究策略,获得底边界流场结构、水体和底边界湍流混合特征、底耗散动力学参数、底颗粒物浓度和梯度变化等规律,建立潮汐、层化、海浪等不同动力条件下底边界动力过程参数化方案,研究沉积物启动、沉降等动力学规律,以数值模式探讨海底拖曳力变化对潮流和环流结构的影响;了解颗粒物组成的季节变化及对起动、再悬浮、絮凝等动力过程的影响,以颗粒物输运模型研究中国近海沉积物源汇分布;以同位素示踪研究底界面交换对动力过程的响应。为解决面临的2个科学问题:①中国近海底边界能量耗散在能量分配中的作用;②中国近海底边界动力过程、颗粒物输运与物质交换的多时空尺度变化规律,奠定基础。

Dynamical processes in the bottom boudary layer（BBL） is the key themes for energy dissipation, particulate material transport and water-sediment exchange in coastal seas. It is the important premise for environment carrying capacity prediction to get more detailed information of BBL dynamics. The development of research of BBL in the world are analyzed. It is suggested that the longterm observation based on a sea-bed triangle fram and column CTD cast in the middle of the Yellow Sea and Changjiang estuary should be carried out in order to obtain the current structure in the BBL, turbulent mixing character through the whole water column, bottom parameters like bottom roughness, friction velocity, bottom drag coeffecient, bottom particles concentration and its gredients variation. Paremeterization of dynamical processes in BBL under different conditions of tide, stratification and waves are needed to study the sediment resuspension and deposition. The influence of bottom drag coeffecient variation on tidal current and residual circulation should be studied by numerical model. It is also important to learn about the seasonal variation of particles composition and its effects on starting, resuspension and flocs. A numeircal model of particulate material transport should be used to study the sediment source and sink in the Chinese coastal water. Isotopic radiation could be used as the tracer for particle movement response to BBL processes and bottom exchange. All above are the bases for two key scientific questions we faced. One is the contribution of bottom dissipation to energy distribution in the coastal sea. The other is the multy spatial and temperal scale variation of BBL processes, particles transport and water-sediment exchange in Chinese coastal seas.