Collaborative Research: Role of mixed layer eddies on phytoplankton productivity in seasonally variable regimes

合作研究：混合层涡流对季节变化条件下浮游植物生产力的作用

• 批准号: 1434512
• 负责人: Amit Tandon
• 金额: $ 32.46万
• 依托单位: University of Massachusetts, Dartmouth
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434512&HistoricalAwards=false
• 关键词: Collaborative; Research; Role; mixed; layer

This study contributes to the understanding of a biologically highly relevant region of the ocean, the subpolar North Atlantic, which acts as a persistent sink for atmospheric carbon. It assesses the biological importance of submesoscale processes, which are not represented in global carbon cycle models. Mixed layer eddies, along with the turbulence induced by air-sea fluxes, modulate both light and nutrients for phytoplankton productivity. This study explores the role of mixed layer eddies on phytoplankton productivity in the subpolar gyres during three distinct phases of the annual cycle - winter, spring, and summer. By modeling the interaction of mixed layer eddies with mesoscale eddies, the study will provide insight on how their coupling affects vertical exchange between the pycnocline and the mixed layer. The project will support a postdoctoral scientist at University of Massachusetts Dartmouth and a Ph.D. student in the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program for four years. The investigators will contribute to outreach efforts including teacher training, and ocean literacy workshops through the Ocean Academy at the Ocean Explorium at New Bedford Seaport by demonstrating ocean dynamics using numerical and tabletop experiments. This study will be amongst the first to include vertical and lateral processes (namely turbulent mixing and 1-10 km scale mixed layer eddies) in understanding the upper ocean's response to temporally varying air-sea fluxes on short time scales (hours-days). By studying the mechanisms generating stratification of deep winter mixed layers, the researchers will assess the effect of eddies and air-sea fluxes on phytoplankton primary productivity during times when a scarcity of light limits photosynthesis (in winter and early spring). By studying the coupling between subsurface mesoscale eddies and the surface submesoscale field subject to intermittent air-sea fluxes, they will examine the advective vertical nutrient supply during periods of strong surface stratification (summer). These process studies will help to address the following important questions about phytoplankton productivity in the subpolar oceans: (i) How is a seed phytoplankton population sustained over the winter? (ii) Is the mechanism for spring stratification, be it eddies or thermal effects, relevant to the net primary productivity over the season? (iii) How are nutrients supplied to the surface layer during times of strong stratification in the summer? This investigation will extend current understanding of mixed layer eddies, which is based on studies in idealized mixed layer settings, by considering their interaction with mesoscale eddies in the pycnocline beneath, and with surface turbulence in response to temporally fluctuating air-sea fluxes.

这项研究有助于了解海洋中与生物高度相关的区域——北大西洋副极地，该区域是大气碳的持久汇。它评估了亚尺度过程的生物学重要性，这些过程在全球碳循环模型中没有体现。混合层涡流以及海气通量引起的湍流调节光和营养物质以促进浮游植物的生产力。 本研究探讨了一年周期三个不同阶段（冬季、春季和夏季）混合层涡流对副极地环流浮游植物生产力的作用。通过模拟混合层涡流与中尺度涡流的相互作用，该研究将深入了解它们的耦合如何影响密斜层和混合层之间的垂直交换。该项目将支持马萨诸塞大学达特茅斯分校的一名博士后科学家和一名博士生。麻省理工学院/伍兹霍尔海洋研究所联合项目的学生四年。研究人员将通过使用数值和桌面实验展示海洋动力学，为新贝德福德海港海洋探索馆海洋学院的教师培训和海洋扫盲研讨会做出贡献。这项研究将是首批纳入垂直和横向过程（即湍流混合和 1-10 公里规模混合层涡流）的研究之一，以了解上层海洋对短时间尺度（小时-天）内随时间变化的海气通量的响应。通过研究深冬混合层分层的机制，研究人员将评估在光线不足限制光合作用的时期（冬季和早春）涡流和海气通量对浮游植物初级生产力的影响。通过研究受间歇性海气通量影响的次表层中尺度涡流与地表次中尺度场之间的耦合，他们将研究强表层分层期间（夏季）的平流垂直养分供应。这些过程研究将有助于解决以下有关副极地海洋浮游植物生产力的重要问题：（i）种子浮游植物种群如何维持越冬？ (ii) 春季分层的机制，无论是涡流还是热效应，与整个季节的净初级生产力有关吗？ (iii) 在夏季强烈分层期间，养分是如何供应到表层的？这项研究将扩展目前对混合层涡流的理解，该理解基于理想化混合层设置的研究，通过考虑混合层涡流与下方重斜层中的中尺度涡流的相互作用，以及与响应时间波动的海气通量的表面湍流的相互作用。