西北太平洋中尺度涡内次中尺度过程的营养盐输运诊断

高分辨率数值模式显示中尺度涡在细微结构下的营养盐受到次中尺度调控比较显著。由于大洋中尺度涡对生态系统生产力具有相当重要的影响，调查清楚次中尺度对涡内营养盐的贡献和空间分布的影响，是量化涡旋对区域海洋生态系统生产力贡献的关键。然而，目前缺乏对外力强迫下次中尺度垂向和水平输运强度演化细节的了解，使我们对涡内次中尺度营养盐实际贡献能力和调整能力的认识不清楚。项目基于即将开展的西北太平洋冷涡观测，分析涡旋细微结构下的营养盐空间分布；基于西北太平洋高分辨率涡旋物理-生态耦合模式，开展数值模拟试验；通过方程定量诊断和粒子示踪分析涡旋内部次中尺度三维营养盐输运能力在风应力调控下的演化过程及其分布格局，旨在回答次中尺度过程对涡内营养盐的贡献多大及对营养盐空间分布的影响如何等关键科学问题。项目的实施有助于进一步了解中小尺度活动在海洋生态系统生产力的作用。

Observational submesoscale filaments of high chlorophyll in global ocean indicate the strong submesoscale upwelling may contribute greatly to nutrient supply in mesoscale eddies. On the other hand, some studies suggest that lateral stirring of submesoscale currents are capable of structuring filaments of chlorophyll and shallow vertical secondary circulations might limit their contributions in nutrient budgets. To address this controversy, quantifying submesoscale nutrient contributions inside mesoscale eddies is in urge as less is known about the net vertical and lateral nutrient transport at submesoscale. Using a Bio-argo, our prior investigation show integral results of vertical chlorophyll at submesoscale regimes are not notably higher than those at other regimes inside the eddy core. We also found the spatial patterns of surface phytoplankton concentration, depth-integral of biomass and vertical nutrient flux are shaped by filaments but evolve decoupling in our high-resolution physical-biological simulations. Therefore, we suggest a fully resolve of the evolution of submesoscale nutrient fluxes at both vertical and horizontal in consideration that submesoscale variabilities are modulated by sea surface forcing, especially winds. Based on a forthcoming cruise observation inside a cyclonic eddy in Northwest Pacific Ocean and numerical simulations designed to test the physical-biological response of an eddy to wind forcing, we are to answer the following critical questions: (1) how does the wind forcing modulate the evolutions of vertical and horizontal nutrient transports at submesoscale? (2) what is the response of spatial nutrient distributions inside the eddy core to the evolutions of submesoscale filaments? The proposal research will help further understand the role of mesoscale eddies in upper ocean nutrient budgets.