Collaborative Research: Kuroshio Extension System Study (KESS) Analysis - Mesoscale Processes

合作研究：黑潮扩展系统研究 (KESS) 分析 - 中尺度过程

• 批准号: 0851246
• 负责人: D. Randolph Watts
• 金额: $ 108.86万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0851246&HistoricalAwards=false
• 关键词: Collaborative; Research; Kuroshio; Extension; System

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The Kuroshio brings warm waters northward in an intense current along the western boundary of the North Pacific. The current departs the Japanese coast to flow eastward as the Kuroshio Extension. This strong jet creates a front between warm subtropical and cold northern waters of the Pacific. Several mechanisms are observed that drive mesoscale processes in the jet, and this variability in turn causes important changes in the regional circulation. A known recirculation gyre exists to the south of the jet, and another one to the north has been confirmed by the recent observations. The dynamic state of this system of circulations alternates on decadal time-scales between weakly meandering and vigorously meandering. Intellectual Merit: Variability in the upper and deep water column is coupled by mesoscale processes in a strong current. This leads to cross-frontal exchanges of heat, salt, and potential vorticity across the Kuroshio Extension, These exchanges in turn are thought to drive long-term changes in the strength and extent of the recirculation gyres. The Kuroshio Extension System Study (KESS) deployed a modern suite of moored instrumentation that spanned the water column, deployed profiling floats, and conducted intensive synoptic surveys and atmospheric soundings. The measurements, centered on the region of maximum mesoscale variability, present a window into mesoscale-driven cross-frontal exchange. The field program, May 2004-June 2006, fortuitously sampled during a regime-transition from weak to vigorous meandering. Initial analyses of KESS data reveal a process-rich circulation field: frontal waves nearly always propagate along the current axis, steep crests and troughs develop intermittently and rings detach to the north and south episodically. The observations highlighted the importance of interactions of deep variable currents with isolated seamounts in generating strong deep cyclones. The KESS data, plus atmospheric and remote-sensing data, will be combined with three state-of-the-art global ocean circulation models to understand the dynamics of mesoscale processes in the Kuroshio Extension. The main driving mechanisms to investigate, combining observations and models, include: 1) barotropic and baroclinic instabilities in the jet, such as frontal waves, steep meanders, rings and radiated waves and eddies; 2) interactions between strong deep eddies and seamounts; and 3) external perturbations upon the Kuroshio Extension from up- and downstream, such as westward propagating eddies and Rossby waves from the mid-Pacific. The important consequences to investigate, combining observations and models, include: 1) exchange of passive and dynamical water properties across the Kuroshio Extension front, caused by mesoscale processes; 2) the role of potential vorticity and momentum budgets in driving the recirculation gyres; 3) how regime shifts may arise from internal and external changes in potential vorticity structure of the Kuroshio Extension and recirculation gyre system.Broader Impacts: The Kuroshio Extension system plays an important role in subtropical-subpolar exchange, the strength of the recirculation gyre, the formation and distribution of mode waters, and the intensification and slowly varying location of the extra-tropical storm track across the North Pacific. An improved understanding of mesoscale dynamics is essential to guide the development and evaluation of global ocean models. A centralized KESS website (http://uskess.org) facilitates community outreach, acts as a data server, provides ready access to all publications, hosts data products such as movies of mapped and derived fields, and provides process-based metrics for numerical models. Three graduate students, a post-doc and a new PhD project scientist will be trained and mentored under this project. Two female undergraduate physics majors will conduct analyses for their senior projects and additional undergraduates will participate through summer REU programs. analyses for their senior projects and additional undergraduates will participate through summer REU programs.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。黑潮将温暖的海水沿北太平洋西部边界以强烈的洋流带向北方。洋流离开日本海岸向东流动，成为黑潮延伸。这股强大的急流在温暖的亚热带和寒冷的太平洋北部水域之间形成了一个锋面。我们观察到驱动急流中尺度过程的几种机制，而这种变异性反过来又引起区域环流的重要变化。一个已知的再循环环流存在于喷流的南部，最近的观测也证实了另一个在北部。这种环流系统的动态状态在年代际尺度上在弱蜿蜒和强蜿蜒之间交替。智力优势：在强水流中尺度过程耦合了上游和深水柱的变率。这导致热、盐和位势涡度在黑潮延伸区横贯锋面交换，这些交换反过来被认为推动了再循环环流强度和范围的长期变化。Kuroshio扩展系统研究（KESS）部署了一套现代化的系泊仪器，该仪器跨越水柱，部署了剖面浮标，并进行了密集的天气调查和大气探测。这些测量集中在中尺度变化最大的区域，为研究中尺度驱动的横锋交换提供了一个窗口。2004年5月至2006年6月的实地项目，碰巧是在一个从弱到强的政体转变过程中取样的。对KESS数据的初步分析揭示了一个过程丰富的环流场：锋面波几乎总是沿着电流轴传播，陡峭的波峰和槽间歇性地发展，环偶尔向北和向南分离。观测结果强调了深海变流与孤立海山的相互作用在产生强深海气旋中的重要性。KESS数据，加上大气和遥感数据，将与三个最先进的全球海洋环流模式相结合，以了解黑潮延伸期中尺度过程的动力学。结合观测和模式研究的主要驱动机制包括：1)射流中的正斜压不稳定性，如锋面波、陡曲、环、辐射波和涡旋等；2)强深涡与海山的相互作用；3)来自上、下游的外部扰动，如太平洋中部向西传播的涡旋和罗斯比波。结合观测和模式研究的重要结果包括：1)由中尺度过程引起的黑潮伸展锋被动水和动力水性质的交换；2)位涡和动量收支在再环流环流驱动中的作用；(3)黑潮伸展和再循环环流系统位涡结构的内外变化如何引起状态转移。更广泛的影响：黑潮扩展系统在副热带-亚极交换、环流强度、模态水的形成和分布以及北太平洋热带外风暴路径的增强和缓慢变化位置等方面发挥重要作用。提高对中尺度动力学的了解对于指导全球海洋模式的发展和评价是必不可少的。集中的KESS网站（http://uskess.org）促进社区外展，充当数据服务器，提供对所有出版物的随时访问，托管数据产品，如映射和派生字段的电影，并为数值模型提供基于过程的度量。本项目将培养和指导3名研究生、1名博士后和1名新的博士项目科学家。两名物理学专业的女本科生将负责高年级项目的分析，另外一些本科生将通过夏季REU项目参与。他们的高级项目分析和额外的本科生将通过夏季REU项目参与。