Upwelling variability in the California Current: bridging local dynamics and climate variability

加州洋流的上升流变化：连接当地动态和气候变化

基本信息

批准号：
1635315
负责人：
Jerome Fiechter
金额：
$ 35.46万
依托单位：
University of California-Santa Cruz
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-15 至 2021-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635315&HistoricalAwards=false
关键词：
Upwelling variability California Current bridging

项目摘要

Coastal upwelling research has a long and rich history in the California Current System, yet a comprehensive description of the interplay between physical processes at local, regional, and basin scales has remained elusive. Seasonal upwelling, driven by strong equatorward alongshore winds, plays a fundamental role in shaping the circulation and ecosystem structure along the west coast of the United States. The main objective of this study is to use high-resolution numerical simulations to characterize variability in the full three-dimensional, time varying circulation associated with wind-driven coastal upwelling in the California Current System. More specifically, the model results will be used to: (i) produce a regional synthesis that rigorously identifies and describes regions of enhanced upwelling in the vicinity of major coastal headlands, and (ii) quantify the impact of regional- and basin-scale processes on local-scale upwelling dynamics. This research will provide significant new insight into how regions of enhanced upwelling contribute to shaping alongshore gradients of physical and biogeochemical properties. Of particular relevance is the connection to coastal ocean acidification and the occurrence and persistence of low pH conditions over the continental shelf along the U.S. west coast. Enhanced upwelling centers are likely to play a key role in determining the spatiotemporal variability of nearshore pH levels, and, therefore, alongshore heterogeneity in the short- and long-term ecosystem response to coastal ocean acidification. This study will increase understanding of how much biogeochemical variability is attributable to physical forcing associated with local upwelling dynamics (as modulated by regional- and basin-scale processes), thereby advancing current knowledge of which coastal regions along the U.S. west coast are more prone to frequent and severe acidification events. In addition, the project will support a postdoctoral researcher at UC Santa Cruz who will gain valuable training in state-of-the-art regional ocean circulation modeling and diagnostic methods, such as adjoint-based calculations. Project outcomes will also be integrated into the graduate curriculum at UCSC, and enhance educational tools available for the community-based Regional Ocean Modeling System (ROMS). Finally, the PIs will present general audience lectures at the Seymour Marine Discovery Center in Santa Cruz, as part of an ongoing series on how seasonal California upwelling will respond to changing climate conditions, and the potential impacts on ecosystem processes and socio-economic services. Coastal upwelling trends and variability determined on the basis of coast-wide averages (i.e., integrated over stronger and weaker upwelling regions) likely compound different dynamical processes and may misrepresent the true nature of the local physical and biogeochemical fluctuations occurring along the U.S. west coast. Therefore, this research will provide significant new insight into how regions of enhanced upwelling in the vicinity of major coastal headlands contribute to shaping the coastal ocean circulation and physical variability at local scales. Outcomes from the numerical experiments will also help determine how regional- and basin-scale variability modulates vertical transport and water mass properties in the vicinity of enhanced upwelling centers and surrounding shelf regions. The most innovative aspect of the project is that it will describe the impacts of local-, regional-, and basin-scale processes on the full 3-dimensional, time-varying ocean circulation associated with coastal upwelling, as opposed to relying on traditional upwelling proxies (e.g., Bakun index) which are often unreliable in regions of intense upwelling or strong onshore geostrophic flow. Another important contribution from this research is that it will demonstrate the benefits of downscaling regional data-assimilative solutions to the local scales at which alongshore variability in upwelling dynamics occurs along the U.S. west coast. Finally, the results from the numerical simulations will complement and enhance another research project, funded under NSF's Coastal SEES Program, focused on quantifying the magnitude, frequency of occurence, and predictability of low pH events along California, as well as their potential impact on coastal ecosystem processes.

沿海上升流研究在加利福尼亚当前系统中具有悠久而悠久的历史，但对本地，区域和盆地量表的物理过程之间的相互作用的全面描述仍然难以捉摸。在沿海风的强烈赤道驱动的季节性上升流中，在塑造美国西海岸的循环和生态系统结构方面发挥了基本作用。这项研究的主要目的是使用高分辨率的数值模拟来表征与加利福尼亚当前系统中与风驱动的沿海上升流相关的整个三维，时间变化的循环。更具体地说，该模型结果将用于：（i）产生一个区域合成，严格识别并描述了主要沿海岬角附近增强上升流的区域，以及（ii）量化区域和盆地尺度过程对局部规模上升上升动力学的影响。这项研究将为增强的上升区域如何促进物理和生物地球化学特性的沿岸梯度构成塑造的区域。特别相关的是与沿海海洋酸化的联系，以及在美国西海岸沿线大陆架上低pH条件的发生和持久性。增强的上升流中心可能在确定近岸pH值的时空变异性方面起关键作用，因此，在短期和长期生态系统对沿海海洋酸化的反应中，沿岸异质性。这项研究将增加对生物地球化学变异性的理解，归因于与局部上升的动态相关的物理强迫（受区域和盆地规模的过程调节），从而促进了当前对美国西海岸沿海地区哪些沿海地区更容易容易出现的频繁和严重酸化事件的知识。此外，该项目将支持加州大学圣克鲁斯分校的博士后研究人员，该研究人员将在最先进的区域循环建模和诊断方法（例如基于伴随的计算）中获得宝贵的培训。项目成果还将集成到UCSC的研究生课程中，并增强可用于基于社区的区域海洋建模系统（ROM）的教育工具。最后，PIS将在圣克鲁斯的西摩海洋发现中心介绍一般听众的演讲，这是一部正在进行的系列赛的一部分，介绍了季节性加利福尼亚上升流将对气候条件的变化以及对生态系统过程和社会经济服务的潜在影响。沿海上升流的趋势和可变性是基于沿海范围的平均值（即集成在较强且较弱的上升区域）可能更复杂的不同动力学过程，并且可能歪曲了发生在美国西海岸的局部物理和生物地球化学波动的真实本质。因此，这项研究将提供有关主要沿海岬角附近增强上升流的地区如何促进沿海海洋循环和当地尺度上的身体变异性的重大见解。数值实验的结果还将有助于确定在增强的上升流中心和周围货架区域附近调节垂直运输和水质量特性的区域尺度变异性。 The most innovative aspect of the project is that it will describe the impacts of local-, regional-, and basin-scale processes on the full 3-dimensional, time-varying ocean circulation associated with coastal upwelling, as opposed to relying on traditional upwelling proxies (e.g., Bakun index) which are often unreliable in regions of intense upwelling or strong onshore geostrophic flow.这项研究的另一个重要贡献是，它将证明将区域数据合并的解决方案降低了当地尺度，在美国西海岸，沿着上升动态发生的沿岸变异性。最后，数值模拟的结果将补充并增强另一个根据NSF的沿海地区资助的研究项目，重点是量化加利福尼亚沿加利福尼亚州沿海pH值的幅度，频率，出现频率和可预测性，以及它们对沿海生态系统过程的潜在影响。