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

• 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

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.

加州洋流系统中的沿海上升流研究有着悠久而丰富的历史，但对当地、区域和盆地尺度物理过程之间相互作用的全面描述仍然难以捉摸。由强烈的赤道沿岸风驱动的季节性上升流在塑造美国西海岸的环流和生态系统结构方面发挥着重要作用。本研究的主要目标是使用高分辨率数值模拟来表征与加州海流系统中风力驱动的沿海上升流相关的完整三维、时变环流的变化。更具体地说，模型结果将用于：（i）生成区域综合报告，严格识别和描述主要沿海岬角附近上升流增强的区域，以及（ii）量化区域和盆地规模过程的影响局部尺度上升流动力学。 这项研究将为了解上升流增强的区域如何影响沿岸物理和生物地球化学性质的梯度提供重要的新见解。特别重要的是与沿海海洋酸化以及美国西海岸大陆架低 pH 条件的发生和持续存在的联系。增强的上升流中心可能在确定近岸 pH 水平的时空变化方面发挥关键作用，因此，在确定沿海海洋酸化的短期和长期生态系统响应中的沿岸异质性方面发挥着关键作用。这项研究将加深对与当地上升流动力学（受区域和盆地规模过程调节）相关的物理强迫造成的生物地球化学变异性的了解，从而加深对美国西海岸哪些沿海地区更容易发生生物地球化学变化的了解。频繁且严重的酸化事件。此外，该项目还将支持加州大学圣克鲁斯分校的一名博士后研究员，他将获得最先进的区域海洋环流建模和诊断方法（例如伴随计算）方面的宝贵培训。项目成果还将纳入 UCSC 的研究生课程，并增强可用于基于社区的区域海洋建模系统 (ROMS) 的教育工具。最后，PI 将在圣克鲁斯的西摩海洋探索中心向公众举办讲座，作为正在进行的系列讲座的一部分，介绍加州季节性上升流将如何应对不断变化的气候条件，以及对生态系统过程和社会经济服务的潜在影响。根据全海岸平均值确定的沿海上升流趋势和变化（即，对较强和较弱上升流区域进行综合）可能会复合不同的动力过程，并可能歪曲美国西海岸发生的局部物理和生物地球化学波动的真实性质。因此，这项研究将为主要沿海岬附近上升流增强的区域如何影响局部尺度的沿海海洋环流和物理变化提供重要的新见解。数值实验的结果还将有助于确定区域和盆地尺度的变化如何调节增强的上升流中心和周围陆架区域附近的垂直输送和水团特性。该项目最具创新性的方面是，它将描述地方、区域和盆地尺度过程对与沿海上升流相关的完整三维、时变海洋环流的影响，而不是依赖传统的上升流在强烈上升流或强烈陆上地转流的地区，代理​​指标（例如巴贡指数）通常不可靠。这项研究的另一个重要贡献是，它将证明将区域数据同化解决方案缩小到局部尺度的好处，在局部尺度上，美国西海岸的上升流动力学发生了沿岸变化。最后，数值模拟的结果将补充和加强由 NSF 沿海 SEES 计划资助的另一个研究项目，重点是量化加利福尼亚州低 pH 事件的规模、发生频率和可预测性，以及它们对沿海的潜在影响生态系统过程。

项目成果

Krill Hotspot Formation and Phenology in the California Current Ecosystem

加州当前生态系统中磷虾热点的形成和物候学

• DOI: 10.1029/2020gl088039
• 发表时间: 2020-06
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Fiechter, Jerome;Santora, Jarrod A.;Chavez, Francisco;Northcott, Devon;Messié, Monique
• 通讯作者: Messié, Monique

Wind, Circulation, and Topographic Effects on Alongshore Phytoplankton Variability in the California Current

风、环流和地形对加州洋流沿岸浮游植物变化的影响

• DOI: 10.1002/2017gl076839
• 发表时间: 2018-04
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Fiechter, Jerome;Edwards, Christopher A.;Moore, Andrew M.
• 通讯作者: Moore, Andrew M.