Abstract Using a validated, three-dimensional, coupled physical-biogeochemical model, this study examines the dynamics of dissolved inorganic carbon (DIC) in the South China Sea (SCS). The model identifies characteristic differences in DIC concentrations between the SCS and adjacent West Philippine Sea (WPS), showing an increase in DIC of up to 140 μmol kg−1 in the upper 2000 m layer from the WPS to the vicinity of the northern SCS. This increasing pattern continues from the northern to the southern SCS, but to a much lower degree ( 1600 m. Exports of DIC occur through other straits and the SCS intermediate water outflow (600 m to 1600 m) via the Luzon Strait. The model shows upward transport of DIC in the upper 400 m and below 1100 m, in contrast to downward DIC transport between 400 m and 1100 m. Seasonally, both DIC concentrations and fluxes in the upper layer have larger dynamic ranges in winter than in summer, attributable to the combined effects of enhanced Kuroshio intrusion, stronger vertical upwelling and greater biogeochemical alterations. A balance of various constitutive DIC terms revealed that horizontal and vertical advection is an order of magnitude greater than the other terms of the DIC budget, which has an opposite sign and thus tends to neutralize each other. The model indicated a decrease in the DIC inventory in the euphotic zone in spring and summer caused by net DIC consumption, and a contrasting increase in fall and winter primarily influenced by DIC vertical transport. In intermediate and deep layers, physical transport processes play a dominant role in the seasonal variation of DIC inventories. In the upper 150 m, DIC fluxes and their stoichiometry with nutrient fluxes, which potentially impact the air-sea CO2 fluxes, are largely driven by excess vertical DIC fluxes compared to horizontal fluxes via the Luzon Strait.

中文翻译：

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南海溶解无机碳动力学：模拟研究

摘要 本研究使用经过验证的三维耦合物理-生物地球化学模型，研究了南海 (SCS) 中溶解无机碳 (DIC) 的动态。该模型确定了南海和邻近的西菲律宾海 (WPS) 之间 DIC 浓度的特征差异，显示从 WPS 到南海北部附近的上部 2000 米层中，DIC 增加了高达 140 μmol kg-1。这种增加的模式从南海北部到南部继续，但程度要低得多（1600 m。DIC 的输出通过其他海峡和 SCS 中间水流出（600 m 至 1600 m）通过吕宋海峡。模型显示DIC 在 400 m 上层和 1100 m 以下向上输送，而 DIC 在 400 m 和 1100 m 之间向下输送。由于黑潮侵入增强、垂直上升流更强和生物地球化学变化更大的综合影响，冬季上层的 DIC 浓度和通量都比夏季的动态范围更大。各种本构 DIC 项的平衡表明，水平和垂直平流比 DIC 预算的其他项大一个数量级，后者具有相反的符号，因此往往会相互抵消。该模型表明，由于 DIC 净消耗量导致春季和夏季透光区 DIC 库存减少，而秋季和冬季则主要受 DIC 垂直运输的影响而增加。在中间层和深层，物理运输过程在 DIC 库存的季节性变化中起主导作用。在上部 150 m，