U.S. GLOBEC: Georges Bank PHASE III Modes of Circulation and Mixing on Georges Bank -- Quantifying Source Water Using the Oxygen Isotope Tracer

9806542费尔班克斯乔治浅滩是世界上研究最多的海洋区域。然而，一个多世纪的生物和物理海洋学测量还没有得出乔治滩生物变异的预测模型。这是美国GLOBEC: Georges银行的一个目标，本项目试图为此做出贡献。乔治海岸上空的环流可以用两种模式来描述：(i)典型模式是一个反气旋环流，源水起源于沿海的缅因湾；（ii）“分流模式”，其特征是苏格兰陆架水直接注入穿过东北海峡到乔治海岸的南侧。本研究的主要目的是对这两种循环模式所解释的生物变异量进行定量评估。该项目将继续使用氧同位素示踪剂h190，该示踪剂已证明具有区分本地和上游淡水来源的独特能力。它揭示了河岸上来自当地河流的淡水百分比的显著年际变化。虽然目前还不清楚负责将水交换到河岸的混合过程的细节，但这些结果表明存在不同的循环和混合模式。评估这些模式对外部强迫变化的敏感性以及对颗粒和溶解成分流入乔治海岸的影响是主要目标。该项目的意义在于定量评价本地和远场水源对乔治滩环境的影响。水分子同位素组成提供了一种将现代气候过程（如径流、海冰、冰盖和海洋降水）与乔治滩水源联系起来的示踪剂。水分子同位素示踪剂是监测气候变化对乔治滩物质起源及其变异影响的最佳方法之一。这项研究将直接有助于建模研究，以了解控制乔治海岸早期生命阶段和鱼类和浮游动物种群补充的物理和生物过程，并为监测任何未来气候变化的影响提供基线。

9806542Fairbanks Georges Bank is the most studied ocean region in the world. However, more than a century of biological and physical oceanographic measurements have not yet lead to a predictive model of Georges Bank biological variability. This is a goal of U.S. GLOBEC: Georges Bank to which this project seeks to make a contribution. Circulation over Georges Bank can be described by two modes: (i) the canonical mode is an anticyclonic gyre with source waters originating in the coastal Gulf of Maine and, (ii) the "shunt mode" which is characterized by direct injection of Scotian Shelf Water across Northeast Channel onto the south flank of Georges Bank. The primary objective of this study is to make a quantitative assessment of the amount of the biological variance explained by these two circulation modes. This project is to continue use of the oxygen isotope tracer H 19 0 which has demonstratedthe unique ability to distinguish local and upstream freshwater sources. It has revealed significant inter-annual variations in the percent of freshwater on the Bank derived from local river sources. Although the details of the mixing processes responsible for exchanging water onto the Bank are not yet clearly understood, these results demonstrate the existence of distinct modes of circulation and mixing. Assessing the sensitivity of these modes to variations in external forcing and the consequences for the flux of particle and dissolved constituents onto Georges Bank is the primary objective. The significance of this project is to bring a quantitative assessment of the influence of local and far-field water sources on the Georges Bank environment. The water molecular isotope composition provides a tracer linking modern climate processes (e.g., runoff, sea ice, ice sheet, and marine precipitation) and Georges Bank source waters. The water molecular isotope tracer is among the best monitors of the impact of changing climate on Georges Bank mass origins and their variability. The research will contribute directly to modeling studies to understand the physical and biological processes controlling the early life stages and recruitment of fish and zooplankton stock on Georges Bank as well as provide a baseline for monitoring the influences of any future climate change.