Coastal and Continental Shelf Oceanography

沿海和大陆架海洋学

• 批准号: 198845-2012
• 负责人: Hay, Alex
• 金额: $ 3.93万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=569837
• 关键词: Coastal; Continental; Shelf; Oceanography

OBJECTIVES: The long-term objective is to predict the dynamic adjustment of the mobile seabed to combined wave-current forcing. The focus of this proposal is the role of bottom stress, and non-linear wave-wave and wave-current interactions, in the adjustment process. Primary objectives are improved knowledge and understanding of: (1) the relationships between wave energy, near-bed fluid turbulence, bottom stress and bed state occurrence; (2) the vertical sediment flux balance and sediment entrainment; (3) the role of higher-order velocity moments in the horizontal sediment flux; and (4) bedform genesis, growth, migration and decay. APPROACH: Acoustic and optical remote sensing technologies are used to obtain comprehensive seabed imagery and velocity, turbulence and suspended sediment concentration profiles spanning the bottom boundary layer. Central to the approach is a recently-developed multi-frequency acoustic Doppler system for remotely measuring velocity, turbulence and sediment flux profiles within the thin wave bottom boundary layer; a laboratory facility for oscillatory-flow boundary layer studies above both fixed-grain and mobile sediment beds; and the use of these sensors in deep-ocean observing systems. 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 the applied science and societal needs for more accurate predictions of seabed change, in the effects of seabed adjustment on the predictability of ocean dynamics, and in the potential for improved interpretation of paleo-environmental conditions through the sedimentary record. The challenge resides in the observational difficulties, in the responses of the mobile sediments and the fluid motions being both mutual and non-linear, and in the fundamental connections to fluid turbulence, one of the great unsolved problems in modern physics. Particular to the coastal and shelf regions of the ocean, relative to other mobile bed environments (rivers, deserts, snow fields), is the central role of forcing by surface gravity waves.

目标：长期目标是预测移动的海床对波流联合作用力的动态调整。本建议的重点是底部应力的作用，以及非线性波波和波流相互作用，在调整过程中。主要目标是增进对以下方面的知识和了解：（1）波能、近床流体湍流、底应力和床况发生之间的关系;（2）垂直沉积通量平衡和沉积物夹带;（3）高阶速度矩在水平沉积通量中的作用;（4）底形成因、生长、迁移和衰减。 方法：利用声学和光学遥感技术获取海底综合图像以及跨越海底边界层的速度、湍流和悬浮泥沙浓度剖面图。这一方法的核心是最近开发的多频声学多普勒系统，用于遥测薄波浪底边界层内的速度、湍流和沉积物通量剖面;用于研究固定颗粒和移动的沉积物床上方湍流边界层的实验室设施;以及在深海观测系统中使用这些传感器。 意义：调整移动的海底沉积物以适应流体强迫变化是现代海洋科学的重要挑战之一。重要的是应用科学和社会需要更准确地预测海底变化，海底调整对海洋动力学可预测性的影响，以及通过沉积记录更好地解释古环境条件的潜力。挑战在于观测困难，在于移动的沉积物和流体运动的相互和非线性响应，以及与流体湍流的基本联系，这是现代物理学中未解决的重大问题之一。相对于其他移动的河床环境（河流、沙漠、雪场），海洋的沿海和大陆架区域尤其如此，表面重力波强迫的中心作用。