Asselot Rémy, Carracedo Lidia I, Thierry Virginie, Mercier Herlé, Bajon Raphaël, Pérez Fiz F
University of Brest, Ifremer, CNRS, IRD, Laboratory of Spatial and Physical Oceanography (LOPS), 29280, Plouzané, France.
Institute of Marine Investigations (IIM, CSIC), 6 Eduardo Cabello Street, 36208, Vigo, Spain.
Nat Commun. 2024 Feb 22;15(1):1630. doi: 10.1038/s41467-024-46074-5.
The subpolar North Atlantic (SPNA) is a region of high anthropogenic CO (C) storage per unit area. Although the average C distribution is well documented in this region, the C pathways towards the ocean interior remain largely unresolved. We used observations from three Argo-O floats spanning 2013-2018 within the SPNA, combined with existing neural networks and back-calculations, to determine the C evolution along the float pathways from a quasi-lagrangian perspective. Our results show that C follows a stepwise deepening along its way through the SPNA. The upper subtropical waters have a stratified C distribution that homogenizes within the winter mixed layer by Subpolar Mode Water formation in the Iceland Basin. In the Irminger and Labrador Basins, the high-C footprint (> 55 μmol kg) is mixed down to 1400 and 1800 dbar, respectively, by deep winter convection. As a result, the maximum C concentration is diluted (<45 μmol kg). Our study highlights the role of water mass transformation as a first-order mechanism for C penetration into the ocean. It also demonstrates the potential of Argo-O observations, combined with existing methods, to obtain reliable C estimates, opening ways to study the oceanic C content at high spatio-temporal resolution.
副极地北大西洋（SPNA）是单位面积人为碳（C）储存量高的区域。尽管该区域的平均碳分布已有详细记录，但碳进入海洋内部的途径在很大程度上仍未得到解决。我们利用了2013年至2018年期间在SPNA内三个Argo-O浮标的观测数据，并结合现有的神经网络和反演计算，从准拉格朗日视角确定了沿浮标路径的碳演变情况。我们的结果表明，碳在通过SPNA的过程中呈逐步加深的趋势。亚热带上层水体具有分层的碳分布，通过冰岛盆地的副极地模态水形成过程，在冬季混合层内实现均匀化。在伊尔明厄和拉布拉多盆地，高碳足迹（>55μmol/kg）在深冬对流作用下分别混合至1400和1800 dbar深度。结果，最大碳浓度被稀释（<45μmol/kg）。我们的研究强调了水体转换作为碳进入海洋的一级机制的作用。它还展示了Argo-O观测结合现有方法获得可靠碳估计值的潜力，为在高时空分辨率下研究海洋碳含量开辟了道路。
