Mechanisms of Decadal Variability in the North Atlantic: The Thermohaline Circulation, Great Salinity Anomalies, and Gulf Stream Path

北大西洋年代际变化机制：温盐环流、大盐度异常和墨西哥湾流路径

• 批准号: 0351383
• 负责人: Geoffrey Vallis
• 金额: $ 44.43万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0351383&HistoricalAwards=false
• 关键词: Mechanisms; Decadal; Variability; North; Atlantic

ABSTRACTOCE-0351383The proposed research is to investigate the physical mechanisms of decadal variability in the North Atlantic ocean. Particularly, it focuses on exploring the hypothesis that Great Salinity Anomalies (GSAs) are a significant contributing factor to such variability, through their effect on the thermohaline circulation, deep western boundary current (DWBC), northern recirculation gyre (NRG) and the north-south shifts of the Gulf Stream path. Preliminary numerical experiments indicate that GSA events have as much if not more effect on decadal ocean variability than do changes in the wind forcing (e.g., variability in the North Atlantic Oscillation) and, on decadal timescales, have a much larger effect than do changes in radiative and surface heat flux changes due to increased greenhouse gases. Furthermore, the interaction between GSA events and the thermohaline circulation may lead to decadal variations of the cyclonic NRG, north-south shifts of the Gulf Stream path and thereby affect the climate of the east coast of the USA. The approach is to investigate these issues with a combination of numerical experimentation and theory, using both simplified and comprehensive numerical ocean models, coupled to slab sea-ice models and a simple model of the atmosphere. These numerical calculations will be supplemented by theoretical investigations of the nature of GSAs and how their interaction with the thermohaline circulation may lead to variations of NGR and north-south shifts of the Gulf Stream path, and hence decadal changes in the mid-latitude ocean circulation. In addition to climate variability, the proposed research addresses some physical-oceanographic problems of long-standing interest, namely the mechanism governing the Gulf Stream separation, the downstream path and the production of cyclonic NRG, and the importance (or otherwise) of the GSA events and their effect on the thermohaline circulation. In addition to an increased understanding of the fundamental nature and causes of ocean and climate variability, the research will lead to a better sense of whether and how high-latitude ocean monitoring is necessary in predicting and detecting decadal climate variability

本研究拟探讨北大西洋年代际变化的物理机制。特别是，它侧重于探索的假设，即大盐度异常（GSA）是一个重要的贡献因素，这种变化，通过其对温盐环流，深西部边界流（DWBC），北方环流环流（NRG）和北方-初步的数值试验表明，GSA事件对十年期海洋变率的影响与风强迫的变化（例如，在十年时间尺度上，这种影响比温室气体增加造成的辐射和地表热通量变化的影响大得多。此外，GSA事件和温盐环流之间的相互作用可能导致气旋NRG的年代际变化，墨西哥湾流路径的南北移动，从而影响美国东海岸的气候。该方法是调查这些问题的数值实验和理论相结合，使用简化和全面的数值海洋模型，再加上平板海冰模型和一个简单的大气模型。这些数值计算将补充GSA的性质，以及它们与温盐环流的相互作用如何可能导致NGR的变化和墨西哥湾流路径的南北移动，从而在中纬度海洋环流的十年变化的理论研究。除了气候变率，拟议的研究解决了一些长期感兴趣的物理海洋学问题，即墨西哥湾流分离的机制，下游路径和气旋NRG的生产，以及GSA事件的重要性（或其他）及其对温盐环流的影响。除了增加对海洋和气候变化的基本性质和原因的了解外，这项研究还将使人们更好地了解高纬度海洋监测在预测和探测十年气候变化方面是否必要以及如何必要