Interannual variability of the Gulf Stream position: The role of atmospheric forcing

墨西哥湾流的位置对美国东北部的区域气候和中大西洋湾的海洋环境有重大影响。墨西哥湾流的北方边缘以一个被称为北墙的尖锐温度锋为标志。虽然墨西哥湾流从海岸分叉的点非常稳定，但北墙的纬度在哈特拉斯角以东的时间尺度上变化很大。拟议的研究将利用观测产品、高分辨率海洋再分析和受大气强迫扰动影响的大西洋涡旋分辨区域模型，诊断将北壁位置年际波动与大气强迫联系起来的动力过程。这些工具将相互补充：观测分析将指导选择应用于区域模式的强迫扰动，区域模式的演变将通过突出可能感兴趣的领域和区域为观测分析提供信息，最后，海洋再分析产品将使我们能够以仅通过观测无法获得的详细程度来研究洋流的演变。拟议的研究将导致更好地了解有助于北墙的可预测性的动力学过程，并形成其位置的动力学预测的基础。这一信息可能对渔业管理人员和参与规划应对恶劣天气事件的地方政府具有重要的实用价值。此外，参与该项目的研究生将接受海洋和大气动力学、洋流数值模拟的现代方法和数据统计分析方面的培训;与本研究相关的出版物将构成博士论文的核心。北壁位置的年际变化与北大西洋涛动（NAO）的变化有关，低（高）NAO阶段之前南（北）移的墨西哥湾流几年，虽然有关于两个系统之间的时间滞后的不确定性。当NAO分解成其分量作用中心（CoA），冰岛低压和亚速尔高压时，北壁位置和NAO之间的相关性显着增强。这些CoA中的每一个都有其自身的动力学和演化，其特征可以通过压力、纬度和经度来表征。NAO只是这些特征的一种可能的线性组合。已经提出了连接北墙的位置和NAO或其组件CoA的几种机制，包括斜压Rossby波沟通东大西洋风态的变化，由于深水生产的变化，以及拉布拉多电流运输的波动，改变了斜坡海的运输和组成的变化，深西部边界电流运输。目前还没有共识的机制是重要的纬度运动的墨西哥湾流北墙。拟议的研究旨在解决我们知识中的这一差距。

The position of the Gulf Stream has a substantial impact on the regional climate of the northeastern United States and the marine environment of the Mid-Atlantic Bight. The northern edge of the Gulf Stream is marked by a sharp temperature front called the North Wall. While the point where the Gulf Stream diverges from the coast is remarkably stable, the latitude of the North Wall varies on a wide range of time scales east of Cape Hatteras. The proposed study will diagnose the dynamical processes linking interannual fluctuations in North Wall position to atmospheric forcing using observational products, high-resolution ocean reanalyses, and an eddy-resolving regional model of the Atlantic Ocean subjected to atmospheric forcing perturbations. Each of these tools will complement each other: the analysis of the observations will guide the selection of forcing perturbations applied to the regional model, the evolution of the regional model will inform the analysis of the observations by highlighting fields and regions of possible interest, and finally, the ocean reanalysis products will allow the evolution of the flow to be examined in a level of detail not available from observations alone. The proposed research will result in an improved understanding of the dynamical processes that contribute to the predictability of North Wall and form the basis for dynamical predictions of its position. This information could have significant utility for fisheries managers and local governments involved with planning responses to severe weather events. In addition, the graduate student involved in the project will be trained in oceanic and atmospheric dynamics, modern approaches to the numerical modeling of oceanic flows, and the statistical analysis of data; publications associated with this research will form the core of a doctoral thesis.Interannual variations in North Wall position have been linked to changes in the North Atlantic Oscillation (NAO), with low (high) NAO phases preceding southward (northward) shifts of the Gulf Stream by several years, although there is uncertainty concerning the time lag between the two systems. Correlations between North Wall position and the NAO are significantly enhanced when the NAO is decomposed into its component centers of action (CoAs), the Icelandic Low and the Azores High. Each of these CoAs has its own dynamics and evolution which can be characterized by pressure, latitude, and longitude. The NAO represents just one possible linear combination of these characteristics. Several mechanisms linking the North Wall's position and the NAO or its component CoAs have been proposed, including changes in the Eastern Atlantic wind regime communicated by baroclinic Rossby waves, variations of deep western boundary current transport due to changes in deep water production, and fluctuations in Labrador Current transport which alter the transport and composition of the Slope Sea. There is currently no consensus on which mechanisms are significant in the latitudinal movement of the Gulf Stream North Wall. The proposed research seeks address this gap in our knowledge.