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。黑潮将温暖的沃茨以强烈的海流沿着北太平洋的西部边界向北输送。海流离开日本海岸向东流动，成为黑潮延伸体。这股强大的急流在太平洋温暖的亚热带和寒冷的北方沃茨之间形成了一个锋面。有几种机制，驱动中尺度过程中的射流，这种变化反过来又会导致区域环流的重要变化。一个已知的再循环环流存在于急流的南部，另一个在北部已被最近的观测所证实。该环流系统的动力状态在十年尺度上在弱曲流和强曲流之间交替。智力优点：上层和深水柱的变化与强水流中的中尺度过程相耦合。这导致了黑潮延伸区的热量、盐和位涡的跨锋面交换，这些交换反过来被认为是推动再循环环流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，这些仪器跨越水柱，部署了剖面浮标，并进行了密集的天气调查和大气探测。的测量，集中在最大的中尺度变化的区域，提出了一个窗口到中尺度驱动的跨锋面交换。2004年5月至2006年6月的实地项目，偶然地在一个从弱到强的蜿蜒状态过渡期间取样。KESS数据的初步分析揭示了一个过程丰富的环流场：锋面波几乎总是传播沿着电流轴，陡峭的波峰和波谷间歇性发展和环分离到北部和南部的episodically。观测结果突出表明，深层可变海流与孤立海山的相互作用在产生强大的深层气旋方面十分重要。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型相结合，以了解黑潮延伸区中尺度过程的动态。结合观测和模型，需要研究的主要驱动机制包括：1）急流中的正压和斜压不稳定性，例如锋面波、陡弯、环以及辐射波和涡旋; 2）强深涡旋与海山之间的相互作用; 3）黑潮延伸区上下游的外部扰动，例如向西传播的涡旋和来自中太平洋的罗斯比波。结合观测和模式研究的重要结果包括：（1）中尺度过程引起的黑潮延伸体锋面被动和动力水性质的交换，（2）位涡和动量收支在驱动再循环涡旋中的作用，（3）黑潮延伸体锋面的动力和被动水性质的交换，（4）位涡和动量收支在驱动再循环涡旋中的作用。第三章黑潮延伸区和再循环环流位涡结构的内部和外部变化如何引起区域变化更广泛的影响：黑潮延伸系统在副热带-副极地交换、再循环环流的强度、模态沃茨的形成和分布以及穿越北太平洋的热带外风暴路径的增强和缓慢变化中起着重要作用。更好地了解中尺度动力学对于指导全球海洋模型的开发和评估至关重要。一个集中的KESS网站（http：uskess.org）促进社区外联，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，如映射和衍生字段的电影，并为数值模型提供基于过程的度量。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。两名女本科物理专业学生将为他们的高级项目进行分析，其他本科生将通过夏季REU课程参与。他们的高级项目和其他本科生的分析将通过夏季REU计划参与。