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.

目的：长期目标是预测移动海床的动态调整，以相结合的波电流强迫。该建议的重点是底部应力的作用，以及在调整过程中的非线性波浪波和波流相互作用。主要目标是改善知识和理解：（1）波能，近床流体湍流，底部压力和床状态的发生之间的关系； （2）垂直沉积物通量平衡和沉积物夹带； （3）高阶速度力矩在水平沉积物通量中的作用； （4）床形的起源，生长，迁移和衰减。 方法：声学和光学遥感技术用于获得横跨底部边界层的综合海床图像和速度，湍流和悬浮沉积物浓度。该方法的核心是最近开发的多频声多普勒系统，用于远程测量薄波底部边界层内的速度，湍流和沉积物通量曲线；固定晶粒和移动沉积物床上的振荡式边界层研究的实验室设施；以及这些传感器在深度观测系统中的使用。 意义：将移动海床沉积物调整为流体强迫变异性是现代海洋科学的重要挑战之一。这一重要性在于应用科学和社会需求，以更准确地预测海床变化，调整海床的影响对海洋动力学的可预测性以及通过沉积记录改善对古环境条件的解释的潜力。挑战在于观察性困难，移动沉积物的反应以及流体运动既是相互的和非线性的，又是与流体湍流的基本联系，这是现代物理学中最大的未解决问题之一。相对于其他移动床环境（河流，沙漠，雪田），海洋的沿海和货架区域尤其是通过表面重力波强迫的核心作用。