Thermocline mixing and vertical oxygen fluxes in the stratified central North Sea
Thermocline mixing and vertical oxygen fluxes in the stratified central North Sea
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DOI：
10.5194/bg-13-1609-2016
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发表时间：
2015-07
期刊：
影响因子：
4.9
通讯作者：
L. Rovelli;M. Dengler;M. Schmidt;S. Sommer;P. Linke;D. McGinnis
中科院分区：
文献类型：
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作者：
L. Rovelli;M. Dengler;M. Schmidt;S. Sommer;P. Linke;D. McGinnis
近几十年来，北海中部一直在经历夏季溶解氧（O2）水平下降的总趋势。为了了解潜在的原因驱动低O2，我们调查了3天的夏季湍流和O2动力学的温跃层和底部边界层（BBL）。该研究的重点是耦合生态地球化学与物理传输过程，以确定BBL内的O2和有机碳周转的关键驱动因素。结合我们的通量观测与分析过程为导向的方法，我们解决驱动程序，最终有助于确定BBL O2水平。我们报告大量的湍流O2通量从温跃层到否则孤立的底层水归因于斜压近惯性波的存在。这种对当地底层水O2和碳预算的贡献在很大程度上被忽视，并显示出在促进底层水高碳周转，同时保持高O2浓度中发挥作用。这一过程可能会随着气候变暖和更强的分层而受到抑制，这些条件可能会促进藻类物种的迁移，从而可能使O2生产区在温跃层内更高。
In recent decades, the central North Sea has been experiencing a general trend of decreasing dissolved oxygen (O2) levels during summer. To understand potential causes driving lower O2, we investigated a 3-day period of summertime turbulence and O2 dynamics in the thermocline and bottom boundary layer (BBL). The study focuses on coupling biogeochemical with physical transport processes to identify key drivers of the O2 and organic carbon turnover within the BBL. Combining our flux observations with an analytical process-oriented approach, we resolve drivers that ultimately contribute to determining the BBL O2 levels. We report substantial turbulent O2 fluxes from the thermocline into the otherwise isolated bottom water attributed to the presence of a baroclinic near-inertial wave. This contribution to the local bottom water O2 and carbon budgets has been largely overlooked and is shown to play a role in promoting high carbon turnover in the bottom water while simultaneously maintaining high O2 concentrations. This process may become suppressed with warming climate and stronger stratification, conditions which could promote migrating algal species that potentially shift the O2 production zone higher up within the thermocline.