Mesoscale contribution to the long-range offshore transport of organic carbon from the Canary Upwelling System to the open North Atlantic
Mesoscale contribution to the long-range offshore transport of organic carbon from the Canary Upwelling System to the open North Atlantic
复制标题
中尺度对有机碳从加那利上升流系统到开放的北大西洋的远距离海上输送的贡献
DOI：
10.5194/bg-15-5061-2018
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发表时间：
2018
期刊：
影响因子：
4.9
通讯作者：
M. Münnich
中科院分区：
文献类型：
--
作者：
E. Lovecchio;N. Gruber;M. Münnich
抽象的。在上升流区域的几项研究表明，中尺度结构，如漩涡和细丝，大大有助于远距离运输的有机碳从近岸地区的生产到近海地区的矿化。然而，还没有提供一个全面的分析，这个中尺度通量及其影响整个加那利上升流系统（CanUS）。在这里，我们填补了这一空白，使用模拟与区域海洋模拟系统（ROMS）耦合到营养物，浮游植物，浮游动物和碎屑（NPZD）生态系统模型。我们运行气候模拟大西洋望远镜网格与涡解决解决的决议在CanUS。使用雷诺通量分解和结构识别算法，我们量化和表征的有机碳通量驱动的细丝和涡流在上100米，并把它们的关系到总的海上运输。我们的分析表明，无论是沿海的细丝和涡流增强近海有机碳通量，但他们的贡献是非常不同的。上升流丝状体以其高速度和高浓度，以非常强烈但沿海受限的方式将有机碳输送到近海，占离岸100 km处有机碳总通量的近80%。细丝的贡献逐渐减少迅速接近零值在1000公里的海岸，导致一个强大的离岸通量的分歧，这是主要的横向来源的有机碳在沿海沃茨高达1000公里的离岸。这种分歧的一部分也是由于丝状体引起了有机碳在100米以下的大量垂直俯冲。由于暗条在时间上的持续性和空间上的重现性，暗条的输运在很大程度上是一种时间平均通量，而时变分量，即，湍流通量相对较小。在距离海岸500公里以上的地方，涡旋主导着中尺度近海输送。虽然它们的贡献仅占总近海通量及其散度的20%，但涡旋，特别是旋风，将有机碳离岸输送到距离海岸2000公里的地方。涡流运输在很大程度上代表了湍流通量，但在这种运输中的条纹突出了典型的形成点和经常性的海上传播途径的存在。虽然涡流传播缓慢，但它们是开放沃茨重要的有机碳储存库，因为它们平均含有该区域三分之一的有机碳，其中三分之二存在于气旋中。我们的分析证实了中尺度过程对近海有机碳输送和北大西洋东部亚热带异养活动的重要性，并强调需要考虑中尺度通量，以充分解决海洋有机碳循环的三维性。
Abstract. Several studies in upwelling regions have suggested that mesoscale structures, such as eddies and filaments, contribute substantially to the long-range transport of the organic carbon from the nearshore region of production to the offshore region of remineralization. Yet a comprehensive analysis of this mesoscale flux and of its impact across the Canary Upwelling System (CanUS) has not been provided. Here, we fill this gap using simulations with the Regional Oceanic Modeling System (ROMS) coupled to a Nutrient, Phytoplankton, Zooplankton and Detritus (NPZD) ecosystem model. We run climatological simulations on an Atlantic telescopic grid with an eddy-resolving resolution in the CanUS. Using both a Reynolds flux decomposition and structure-identification algorithms, we quantify and characterize the organic carbon fluxes driven by filaments and eddies within the upper 100 m and put them in relationship to the total offshore transport. Our analysis reveals that both coastal filaments and eddies enhance the offshore flux of organic carbon, but that their contribution is very different. Upwelling filaments, with their high speeds and high concentrations, transport the organic carbon offshore in a very intense, but coastally confined manner, contributing nearly 80 % to the total flux of organic carbon at 100 km offshore. The filament contribution tapers off quickly to near zero values at 1000 km off the coast, leading to a strong offshore flux divergence that is the main lateral source of organic carbon in the coastal waters up to 1000 km offshore. Some of this divergence is also due to the filaments inducing a substantial vertical subduction of the organic carbon below 100 m. Owing to the temporal persistence and spatial recurrence of filaments, the filament transport largely constitutes a time-mean flux, while the time-varying component, i.e., the turbulent flux, is comparatively small. At distances beyond 500 km from the coast, eddies dominate the mesoscale offshore transport. Although their contribution represents only 20 % of the total offshore flux and its divergence, eddies, especially cyclones, transport organic carbon offshore to distances as great as 2000 km from the coast. The eddy transport largely represents a turbulent flux, but striations in this transport highlight the existence of typical formation spots and recurrent offshore propagation pathways. While they propagate slowly, eddies are an important organic carbon reservoir for the open waters, as they contain, on average, a third of the organic carbon in this region, two thirds of which is found in cyclones. Our analysis confirms the importance of mesoscale processes for the offshore organic carbon transport and the fueling of the heterotrophic activity in the eastern subtropical North Atlantic, and highlights the need to consider the mesoscale flux in order to fully resolve the three-dimensionality of the marine organic carbon cycle.
影响因子：
4.9
作者：
J. Karstensen;F. Schütte;A. Pietri;G. Krahmann;B. Fiedler;D. Grundle;H. Hauss;A. Körtzinger;C. Löscher;P. Testor;N. Vieira;M. Visbeck
通讯作者：
J. Karstensen;F. Schütte;A. Pietri;G. Krahmann;B. Fiedler;D. Grundle;H. Hauss;A. Körtzinger;C. Löscher;P. Testor;N. Vieira;M. Visbeck