Circulation and Transport in the Hudson Shelf Valley

人们早就知道，大陆架上的海底山谷和大陆坡上的海底峡谷是跨越大陆架和大陆坡运送沉积物、营养物和生物有机体等物质的重要通道。 以前的研究几乎完全集中在较深的大陆坡峡谷。 与斜坡峡谷相反，较浅的陆棚山谷受到风和波浪等表面和底部作用力的强烈影响，并且经常受到分层的季节性变化的影响。 与斜坡峡谷形成对比的还有，陆架谷延伸到浅水区，那里的沉积物迁移和生物过程特别活跃，因此可能有助于沉积物跨陆架迁移和营养物质上涌到近地表真光层。 大陆架谷是受人类活动影响最大的大陆架区域与大陆坡和开阔洋的深沃茨之间的直接联系，研究目标以以往对斜坡峡谷的研究和对哈德逊大陆架谷观测结果的初步分析为指导，这是一个狭窄的长谷，横穿中大西洋湾的大陆架。 哈德逊大陆架谷的沿谷（跨大陆架）流动主要是风力驱动的，经常达到50厘米/秒，比邻近大陆架上的跨大陆架流动大一个数量级，使其成为跨大陆架交换的重要通道。 我们的目标是一个定量的了解流在货架山谷，特别是沿谷运输，风强迫，将广泛相关的范围广泛的货架山谷的响应。 该方法是一个序列的理想化的数值模拟运行的目的是了解动态和量化的运输和垂直结构的流在货架谷的相关无量纲参数，并补充现有的观测分析从哈德逊货架谷和更现实的模拟哈德逊货架谷，以评估的相关性的理想化模型的结果，一个现实的货架谷。 将利用对历史观测的分析和数值模拟来解决有关大陆架河谷环流和输送以及河谷水流对大陆架热量、盐分和养分平衡的贡献的基本科学问题。更好地了解陆架谷，特别是哈德逊陆架谷的环流和运输，将为研究大陆架上的生物生产力和污染物/幼虫扩散提供物理背景。 它还将有助于量化大陆架和陆坡海之间的示踪剂和动量交换。 该项目将通过全日制研究生和本科生的参与产生教育影响。

It has long been known that submarine valleys over continental shelves and submarine canyons over continental slopes provide important pathways for transporting material such as sediment, nutrients and biological organisms across continental shelves and slopes. Previous studies have focused almost exclusively on deeper continental slope canyons. In contrast to slope canyons, shallower shelf valleys are strongly influenced by surface and bottom forcing, such as winds and waves, and often subject to large seasonal variations in stratification. Also in contrast to slope canyons, shelf valleys extend into shallow water, where sediment transport and biological processes are particularly active, and can therefore potentially facilitate cross-shelf transport of sediment and upwelling of nutrients to the near-surface euphotic zone. Shelf valleys provide a direct connection between the shelf region that is most strongly impacted by human activity and deep waters of the continental slope and open ocean.The research objectives are guided by previous studies of slope canyons and preliminary analysis of observations in Hudson Shelf Valley, a narrow and long valley that cuts across the continental shelf of the Middle Atlantic Bight. Along-valley (cross-shelf) flows in Hudson Shelf Valley are primarily wind-driven and often reach 50 cm/s, an order of magnitude larger than cross-shelf flows on the adjacent continental shelf, making it an important conduit for cross-shelf exchange. The goal is a quantitative understanding of the response of flows in shelf valleys, particularly the along-valley transport, to wind forcing that will be broadly relevant to a wide range of shelf valleys. The approach is a sequence of idealized numerical modeling runs aimed at understanding the dynamics and quantifying the transport and vertical structure of the flow in shelf valleys in terms of relevant non-dimensional parameters, and complemented by analysis of existing observations from Hudson Shelf Valley and more realistic simulations of Hudson Shelf Valley to evaluate the relevance of the idealized model results to a realistic shelf valley. Analysis of historical observations and numerical simulations will be used to address fundamental scientific questions concerning the circulation and transport in shelf valleys and the contribution of valley flows to heat, salt and nutrient balances on the shelf.Broader impacts: Better understanding of the circulation and transport in shelf valleys, and specifically Hudson Shelf Valley, will provide the physical background for studies of biological productivity and contaminant/larval dispersal on the shelf. It will also help quantify tracer and momentum exchanges between the continental shelf and the slope sea. The project will have educational impacts through the involvement of a full-time graduate student and participation by undergraduate students.