Coastal and Continental Shelf Oceanography

目的：长期目标是改进对近岸和大陆架环境中移动床对波流联合强迫的动态调整的预测。主要的短期目标是利用和发展先进的声学遥感系统来研究主动运输条件下底部边界层动量和沉积物的湍流通量，以及大流量潮汐通道湍流的极值统计。方法：(1)在实验室和野外实验中，采用自主研发的高分辨率、湍流分辨率、多频声学多普勒分析系统，远程测量不断演变的移动床上的速度、湍流和沉积物通量的时空结构。(2)利用现场快速响应湍流探测直接和远程多普勒声学系统研究高流量潮汐通道中深度湍流在1秒至1个月时间尺度上的变化。(3)利用仪器化地表机器人研究风暴期间近岸带和内大陆架移动床对波浪流强迫的调节，以及大流量潮汐通道中沙丘和巨型沙丘对强烈湍流和逆流条件的调节。******意义：海底活动沉积物对流体强迫变率的调节是现代海洋科学的重要挑战之一。其重要性在于：(A)应用科学和社会需要更准确地预测与海岸线和沿海基础设施保护有关的海床变化，传统上，现在包括海床稳定性对使用流内涡轮机进行可再生水力发电的高流量潮汐通道潜在开发的影响；(B)湍流和海床调整对海岸和大陆架环境条件可预测性的影响，以及(C)通过沉积记录改进对古环境条件解释的潜力。挑战在于：(1)观测困难；(2)流动沉积物的响应和上覆流体的运动是相互的和非线性的；(3)与流体湍流的基本联系，这是经典物理学中尚未解决的重大问题之一。**

OBJECTIVES: The long-term goal is improved predictions for the dynamic adjustment of mobile beds to combined wave-current forcing in nearshore and continental shelf environments. The primary short term goal is to pursue the use and development of advanced acoustic remote sensing systems for investigating the turbulent fluxes of momentum and sediment in the bottom boundary layer under active transport conditions, and the extreme value statistics of turbulence in high-flow tidal channels.******APPROACH: (1) A state-of-the art, high-resolution, turbulence-resolving, multi-frequency acoustic Doppler profiling system developed in-house will be used in laboratory and field experiments to remotely measure the space-time structure of velocity, turbulence and sediment flux above evolving mobile beds. (2) The variability of turbulence on 1-second to 1-month time scales will be investigated at mid-depth in high-flow tidal channels both directly, using in situ fast-response turbulence probes, and remotely, using multiple advanced acoustic Doppler systems. (3) Mobile bed adjustment to wave-current forcing in the nearshore zone and inner continental shelf during storms, and adjustment of dunes and mega-dunes to the intense turbulence and reversing current conditions in high-flow tidal channels, will be investigated using an instrumented robotic surface vehicle. ******SIGNIFICANCE: The adjustment of mobile seabed sediments to fluid forcing variability is one of the important challenges in modern ocean science. The importance resides in: (A) the applied science and societal needs for more accurate predictions of seabed change related to shoreline and coastal infrastructure protection traditionally, and now including the effects of seabed stability on the potential development of high-flow tidal channels for renewable hydroelectric power generation using in-stream turbines; (B) the effects of turbulence and seabed adjustment on the predictability of coastal and shelf-wide environmental conditions, and (C) in the potential for improved interpretation of paleo-environmental conditions through the sedimentary record. The challenges reside in: (1) the observational difficulties, (2) in the responses of the mobile sediments and the motion of the overlying fluid being both mutual and non-linear, and (3) in the fundamental connections to fluid turbulence, one of the great unsolved problems in classical physics. **