Impacts of Gulf Stream Warm-Core Rings on Gulf of Maine Circulation

缅因湾是一个具有重要生态和经济意义的边缘海域。受当地和远程强迫的影响，缅因湾的物理和生态系统目前正在经历迅速的变化。海湾与不同水团的斜坡海和斯科特陆架进行了显著的水交换。坡面水多见于海湾深部盆地，具有很大的变异性。通过改变盆地中的密度分布，入侵的斜坡水域可能会改变近岸环流，影响海洋物种沿陆架的运输。因此，研究缅因湾和斜坡海之间的水交换对于了解海湾不同的自然和生态环境，包括再次发生有害藻华的动态至关重要。本研究旨在探讨与湾流暖核环相关的较短时间尺度上缅因湾和坡海相互作用的基本动力学和区域影响。该项目的成果将惠及沿海渔业和公共卫生，这项工作涉及高中生和本科生。它们与东北航道独特的地形相互作用，影响航道内的水流。提出了暖核环与缅因湾相互作用的三种可能模式：1)暖核环驱动东北航道的外流，作为环东北侧离岸流动拖缆的一部分；2)环翼在岸上的运动导致斜坡/环水侵入航道；3)暖核环推动陆架斜坡前岸，并通过沿陆架传播的锋面弯道加强航道内振荡交换流动的产生。研究基于两个基本假设：1)邻近斜坡海的暖核环活动在东北海峡引起强气流，导致缅因湾和斜坡海之间显著的热量和盐分交换；2)由暖核环引起的航道流入带来了密集的斜坡水域，并调节了缅因湾深水团和沿海环流的特征。这些假设将通过分析现有的现场观测、卫星测量、面向过程的理想化模式模拟和现实的区域模式后播模拟来检验。

The Gulf of Maine is a marginal sea of critical ecological and economical importance. Influenced by both local and remote forcing, the Gulf of Maine physical and ecological system is currently experiencing rapid changes. The gulf undergoes significant water exchanges with the slope sea and the Scotian Shelf of distinct water masses. The slope waters are often found in the deep basins in the gulf and display a wide range of variability. Through modifying density distribution in the basins, the intruding slope waters can potentially alter the near-shore circulation and affect the along-shelf transport of marine species. Studying the water exchange between the Gulf of Maine and the slope sea is thus crucial for understanding the varying physical and ecological environment in the gulf, including the dynamics of reoccurring harmful algal blooms. This study aims to address the fundamental dynamics and regional influences of the interaction between the Gulf of Maine and Slope Sea on shorter time scales associated with Gulf Stream warm core rings. The outcome of this project will benefit coastal fisheries and public health and the work involves participation of high school and undergraduate students.Warm core rings are major events in the continental slope region. They interact with the unique topography at the Northeast Channel and affect the flow within the channel. Three possible modes of interactions between warm core rings and the Gulf of Maine are proposed: 1) A warm core ring drives outflow in the Northeast Channel as part of the offshore flowing streamer on the northeast side of the ring; 2) onshore motion of a ring limb causes intrusion of slope/ring waters into the channel; 3) a warm core ring pushes the shelf-slope front shoreward and enhances the generation of oscillatory exchange flows in the channel by along-shelf propagating frontal meanders. The study is based on two general hypotheses: 1) warm core rings activities in the adjacent slope sea induce strong flows in the Northeast Channel, resulting in significant heat and salt exchange between the Gulf of Maine and the slope sea; and 2) the warm core ring-induced inflow in the channel brings in dense slope waters and modulates the characteristics of the deep water masses and the coastal circulation in the Gulf of Maine. These hypotheses will be tested through the analysis of available in situ observations, satellite measurements, process-oriented idealized model simulations, and realistic regional model hindcast simulations.