Counteracting Contributions of the Upper and Lower Meridional Overturning Limbs to the North Atlantic Nutrient Budgets: Enhanced Imbalance in 2010
Counteracting Contributions of the Upper and Lower Meridional Overturning Limbs to the North Atlantic Nutrient Budgets: Enhanced Imbalance in 2010
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DOI：
10.1029/2020gb006898
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发表时间：
2021-06-01
影响因子：
5.2
通讯作者：
Perez, F. F.
中科院分区：
文献类型：
--
作者：
Carracedo, L., I;Mercier, H.;Perez, F. F.
北大西洋海盆是大气二氧化碳的主要汇，部分原因是在三维海洋环流提供的营养物的支持下，形成了广泛的浮游生物大量繁殖。因此，海洋环流和/或分层的变化可能会影响初级生产和生物碳输出。在这项研究中，我们评估了这种可能性，通过评估无机营养预算2004年和2010年在北大西洋的基础上，从跨大西洋A05-24.5度N和格陵兰-葡萄牙OVIDE水文剖面，我们应用了一个盒子逆模型来解决流通和估计横截面营养输送的观测。完整的水柱营养收支分为上、下纬向翻转环流（MOC）分支。根据我们的结果，2010年初的异常环流与极端负NAO条件有关，导致上翻转翼增强了营养丰富的沃茨水向北平流，从而导致硝酸盐和磷酸盐在24.5度以北发生显着收敛。与等密度线的起伏相结合，2010年的异常环流事件有利于增加营养消耗（5.7 +/- 4.1 kmol-Ps（-1））和相关的生物CO2吸收（0.25 +/- 0.18 Pg-C年（-1），上限估计），这代表了该地区年平均海-气CO2通量的50%。我们的研究结果还表明，在这两年的深层硅酸盐分歧的瞬态。这两个结果都表明MOC驱动的调制的生物碳吸收（由MOC上翼）和营养物质库存（由MOC下翼）在北大西洋。
The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three-dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assess this possibility by evaluating inorganic nutrient budgets for 2004 and 2010 in the North Atlantic based on observations from the transatlantic A05-24.5 degrees N and the Greenland-Portugal OVIDE hydrographic sections, to which we applied a box inverse model to solve the circulation and estimate the across-section nutrient transports. Full water column nutrient budgets were split into upper and lower meridional overturning circulation (MOC) limbs. According to our results, anomalous circulation in early 2010, linked to extreme negative NAO conditions, led to an enhanced northward advection of more nutrient-rich waters by the upper overturning limb, which resulted in a significant nitrate and phosphate convergence north of 24.5 degrees N. Combined with heaving of the isopycnals, this anomalous circulation event in 2010 favored an enhancement of the nutrient consumption (5.7 +/- 4.1 kmol-P s(-1)) and associated biological CO2 uptake (0.25 +/- 0.18 Pg-C yr(-1), upper-bound estimate), which represents a 50% of the mean annual sea-air CO2 flux in the region. Our results also suggest a transient state of deep silicate divergence in both years. Both results are indicative of a MOC-driven modulation of the biological carbon uptake (by the upper MOC limb) and nutrient inventories (by the lower MOC limb) in the North Atlantic.