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。黑潮在北太平洋西部边界的强烈洋流中将温暖的海水带到北部。洋流离开日本海岸，随着黑潮的延伸向东流动。这股强劲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道锋面。观察到了几种驱动喷流中尺度过程的机制，这种可变性反过来又导致区域环流的重要变化。已知的环流涡旋存在于急流的南面，另一个位于北面的环流环流已被最近的观测所证实。这一环流系统的动态在十年时间尺度上在弱曲折和剧烈曲折之间交替。智力优势：上层和深层水柱的可变性与强流中的中尺度过程相结合。这导致了黑潮延伸区的热量、盐分和位涡的跨锋面交换，这些交换反过来被认为推动了再循环涡旋的强度和范围的长期变化。黑潮延伸系统研究(KESS)部署了一套现代化的系泊仪器，跨越了水柱，部署了剖面浮标，并进行了密集的天气调查和大气探测。以中尺度变率最大的区域为中心的测量，为中尺度驱动的跨锋面交换提供了一个窗口。2004年5月至2006年6月的实地考察计划，是在一个政权从虚弱到充满活力的曲折过渡期间偶然抽样的。对KESS资料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海流轴传播，陡峭的波峰和波谷间歇性地发展，环带周期性地向北和南分离。观测结果强调了深部可变洋流与孤立海山相互作用在产生强烈深部气旋方面的重要性。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，以了解黑潮延伸区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)急流中的正压和斜压不稳定，如锋面波、陡峭的弯道、环和辐射波和涡旋；2)强深涡和海山之间的相互作用；3)从上下游对黑潮延伸的外部扰动，如来自中太平洋的向西传播的涡旋和Rossby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穿过黑潮延伸锋的被动和动力水性质的交换；2)位涡和动量收支在驱动再环流涡旋中的作用；3)黑潮延伸和再环流涡旋系统内部和外部位涡结构的变化如何引起形势变化。更广泛的影响：黑潮延伸系统在副热带-副极地交换、再环流涡旋的强度、模态水的形成和分布以及跨北太平洋的热带风暴路径的加强和缓慢变化中起着重要作用。增进对中尺度动力学的理解对于指导全球海洋模式的发展和评估至关重要。一个集中的KESS网站(http://uskess.org))为社区推广提供便利，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，如地图和派生领域的电影，并为数字模型提供基于过程的指标。三名研究生、一名博士后和一名新的博士项目科学家将在该项目下接受培训和指导。两名物理专业的女本科生将为她们的高级项目进行分析，更多的本科生将通过暑期REU项目参与。对他们的高级项目和其他本科生的分析将通过夏季REU项目参与。