Circulation and Exchange Across the Inner Shelf - The Importance of Surface Gravity Waves and Cross-shelf Wind Stress

沿海海洋学中最重要的问题之一是确定跨大陆架交换的机制和途径（例如Ocean Sciences 2001）。跨大陆架和内部大陆架上的垂直交换对广泛的跨学科过程产生重大影响，包括沿海上升流期间向光带提供营养物质，河口或潮间水域与中大陆架之间生物在其生命周期不同阶段的运动，沉积物的近海运动，污染物的近海扩散以及污染物的沉积，如石油泄漏到海滩上。尽管内大陆架很重要，但内部大陆架交换的主要机制和相关的动力学仍然不确定。很少有人试图弥合以波浪驱动过程为重点的近岸表层研究和以风力驱动过程为重点的陆架研究之间的差距（参见Lentz等人2001年的例外）。因此，近岸模式通常关注于表层，通常不考虑风强迫或分层，而陆架模式通常不包括波浪强迫（例如Austin and Lentz 2002）。在这项研究中，伍兹霍尔海洋研究所的研究人员将研究大陆架内部大部分地区的跨大陆架环流和交换是否受到表面重力波和跨大陆架风应力的强迫。为此，科学家将分析来自沿海观测站的现有观测结果和以前的大陆架内部研究。将在玛莎葡萄园岛海岸天文台（MVCO）部署一个三单元跨大陆架内部阵列，以获得密度和电流剖面，以确定分层对跨大陆架环流的影响。将使用MVCO现有的4年时间序列的2 hz ADCP数据对应力剖面进行直接协方差估计，并将开发波浪驱动的跨大陆架环流的简单分析模型。最后，采用湍流闭合方案的二维原始方程数值模型来研究分层和地表热通量对风浪驱动环流的影响。这项工作的目标是对内大陆架上的风和波驱动的环流进行动力学理解。此外，该研究还将通过在原始方程数值模型中提供经过观测验证的地表重力波强迫参数化和应力观测来评估和改进现有湍流关闭方案，从而增强沿海海洋学界可用的三维数值模拟能力。

One of the most important problems in coastal oceanography is determining the mechanisms and pathways of cross-shelf exchange (e.g. Ocean Sciences 2001). Cross-shelf and vertical exchange over the inner shelf has a major impact on a wide range of interdisciplinary processes, including the supply of nutrients to the euphotic zone during coastal upwelling, the movement of organisms between estuarine or inter-tidal waters and the mid shelf during different stages of their life cycles, the on-offshore movement of sediment, the offshore dispersal of pollutants, and the deposition of contaminants such as oil spills onto beaches. Despite the importance of the inner shelf, the dominant mechanisms responsible for exchange across the inner shelf and the associated dynamics remain uncertain. There have been few attempts to bridge the gap between nearshore surfzone studies focusing on wave-driven processes and shelf studies focusing on wind-driven processes (see Lentz et al 2001 for an exception). Consequently, nearshore models generally focus on the surfzone and typically do not consider wind forcing or stratification, while shelf models generally do not include wave forcing (e.g. Austin and Lentz 2002). In this study, researchers at the Woods Hole Oceanographic Institution will examine whether or not the cross-shelf circulation and exchange over a substantial portion of the inner shelf is forced by surface gravity waves and cross-shelf wind stresses. To do so, the scientist will analyze existing observations from coastal observatories and previous inner-shelf studies. A three element cross-innershelf array at the Martha's Vineyard Coastal Observatory (MVCO) will be deployed to obtain density and current profiles to determine the impact of stratification on the cross-shelf circulation. Direct covariance estimates of stress profiles will be made using an existing four-year time series of 2-Hz ADCP data from the MVCO, and a simple analytic model of the wave-driven cross-shelf circulation will be developed. Finally, a two-dimensional primitive-equation numerical model with a turbulence closure scheme will be used to investigate the influence of stratification and surface heat flux on the wind- and wave-driven circulation. The goal of this work is to reach a dynamical understanding of the wind-and wave-driven circulation over the inner shelf. In addition, the research will enhance the three-dimensional numerical modeling capability available to the coastal oceanographic community by providing observationally tested parameterizations of surface-gravity-wave forcing in a primitive-equation numerical model and stress observations for evaluating and refining existing turbulence closure schemes.