Collaborative Research: On the importance of Submesoscale processes for ocean productivity

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。将进行一系列数值模拟研究，以检查营养物质平流到海洋的光表层，以支持浅层浮游生物的浮游植物生产力的过程。模式实验旨在验证两种相互竞争的假设：(1)中尺度涡旋通过涡旋泵和涡旋/风相互作用将营养物上涌；(2)亚中尺度（110 km尺度和O(1) rosby数）锋面过程支持的地转垂直运动是营养物垂直通量的主要原因。本文旨在扩展对上层海洋亚中尺度过程的新认识，以探索其对生物地球化学运输和海洋生产力的影响。生物地球化学性质通量（即反应性示踪剂的运输）不仅受到物理的影响，而且受到生物反应（示踪剂的来源和汇）的影响。该项目将把简单的生物模型与复杂的物理模型结合起来，从完全非流体静力、三维（PE）模型到表面准营养（SQG）和半营养（SG）反演，以衡量物理过程对生物生产力的影响。为了更好地理解中尺度和亚中尺度物理的作用，该团队将同时模拟这两个尺度，描述Ro1（中尺度）和Ro=O(1)（亚中尺度）过程，并将浮游植物营养物质的垂直运输归因于不同物理情景下的特定尺度和过程。我们将结合物理和生物特性（涡度、速度、密度、营养和光）分析水包的路径，以获得中尺度和亚中尺度物理和生物耦合的拉格朗日观点。重点将放在三组重要的问题上。(1)与中尺度过程相比，亚中尺度过程对垂直养分输送的贡献是什么？哪个物理时间尺度（中尺度或亚中尺度）与生物学最相称，并能提高营养物质运输的效率？(2)不同过程和尺度下的垂直速度结构是怎样的？侧向密度梯度、混合层深度、斜斜分层和地表强迫对其有何影响？(3) SQG（以及SG和QG）逆温在多大程度上反映了亚中尺度垂直速度结构和输送？更广泛的影响在几个生物地球化学和物理背景下，斜斜和海洋表面混合层之间的垂直输送是重要的。因此，这项研究具有广泛的意义。在亚中尺度上，生物学与物理学的耦合是相对未被探索的。这些发现将有助于解释生物学观察结果，并确定110公里尺度的物理学是否确实与碳循环模型中的生产力有关。pi将通过与在黑潮进行测量的日本小组、试图解释高分辨率卫星测量的挪威小组以及onr资助的亚中尺度横向混合示踪剂释放研究的合作，将建模和分析工作与观测联系起来。该项目将支持两名博士后研究人员，他们将接受建模和分析、结果发表和展示以及协作规划活动方面的培训。这些pi将通过新贝德福德的海洋探索中心和波士顿大学的暑期路径项目参与教育和推广活动。女科学家将在这个项目中发挥重要作用，并将在研究和推广方面发挥榜样作用。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).A hierarchy of numerical modeling studies will be performed to examine the processes by which nutrients are advected into the euphotic surface layer of the ocean to support phytoplankton productivity in pelagic regions with shallow pcynoclines. The model experiments are designed to test two competing hypotheses (i) that nutrients are upwelled by mesoscale eddies through eddy-pumping and eddy/wind interaction, vs. (ii) that the ageostrophic vertical motions supported by submesoscale (110 km scale, and O(1) Rossby number) frontal processes are largely responsible for the vertical nutrient fluxes. This proposal aims to extend the newly emerging understanding of submesoscale processes in the upper ocean to exploring their impact on biogeochemical transport and ocean productivity.Intellectual MeritBiogeochemical property fluxes (i.e. the transport of reactive tracers) are affected not only by physics, but also by biological reactions (sources and sinks for the tracers). This project will couple simple biological models with physical models ranging in complexity from the fully nonhydrostatic, three-dimensional (PE) model to the surface-quasigeostrophic (SQG) and semigeostrophic (SG) inversions, to gauge the effects of physical processes on biological productivity. To better understand the contribution of meso- and submeso-scale physics, the team will model both scales simultaneously, delineate between Ro1 (mesoscale) and Ro=O(1)(submesoscale) processes, and ascribe the vertical transport of phytoplankton nutrient to specific scales and processes under various physical scenarios. The pathways of water parcels will be analyzed in conjunction with physical and biological properties (vorticity, velocity, density, nutrient, and light) to gain a Lagrangian view of physical and biological coupling at meso- and sub-mesoscales.The focus will be on three important sets of questions. (1) What is the contribution of submesoscale processes to vertical nutrient transport in comparison to mesoscale processes? Which physical time scales (meso- or submeso-scale) are most commensurate with the biology and enhance the efficacy of nutrient transport? (2) What is the structure of the vertical velocity associated with different processes and scales? How is this affected by lateral density gradients, mixed layer depth, pycnocline stratification, and surface forcing? (3) How well do the SQG (and the SG and QG) inversions represent the submesoscale vertical velocity structure and transport?Broader ImpactsVertical transport between the pycnocline and surface mixed layer of the ocean is of importance in several biogeocehemical and physical contexts. Hence this study has broad implications. Coupling of biology to physics at submesoscales is relatively unexplored. The findings will help interpret biological observations and determine if indeed 110 km scale physics is relevant for productivity in carbon cycle models. The PIs will link this modeling and analysis work to observations by collaboration with a Japanese group making measurements in the Kuroshio, Norwegian group attempting to interpret high resolution satellite measurements, and an ONR-funded tracer release study of submesoscale lateral mixing. The project will support two postdoctoral researchers who will be trained in modeling and analysis, publication and presentation of results, and collaborative planning activities. The PIs will participate in education and outreach activities through the Ocean Explorium at New Bedford and the Summer Pathways program at Boston University. Women scientists will play an important role in this project and will serve as role models in research and outreach.