Water mass pathways to the North Atlantic oxygen minimum zone

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Peña-Izquierdo, Jesús, van Sebille, E., Pelegrí, Josep Lluís, Sprintall, Janet, Mason, Evan, Llanillo, P. J., Machín, Francisco
• Other Authors: Australian Research Council, Ministerio de Economía y Competitividad (España)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2015
• Subjects: Izquierdo; North Atlantic
• Online Access: http://hdl.handle.net/10261/123830; https://doi.org/10.1002/2014JC010557; https://doi.org/10.13039/501100000923; https://doi.org/10.13039/501100003329

23 pages, 14 figures, 1 table, supporting information https://doi.org/10.1002/2014JC010557 The water mass pathways to the North Atlantic Oxygen Minimum Zone (naOMZ) are traditionally sketched within the cyclonic tropical circulation via the poleward branching from the eastward flowing jets that lie south of 10°N. However, our water mass analysis of historic hydrographic observations together with numerical Lagrangian experiments consistently reveal that the potential density level of σ θ = 26.8 kg m -3 (σ26.8, approximately 300 m depth) separates two distinct regimes of circulation within the Central Water (CW) stratum of the naOMZ. In the upper CW (above σ26.8), and in agreement with previous studies, the supply of water mainly comes from the south with a predominant contribution of South Atlantic CW. In the lower CW (below σ26.8), where minimal oxygen content is found, the tropical pathway is instead drastically weakened in favor of a subtropical pathway. More than two thirds of the total water supply to this lower layer takes place north of 10°N, mainly via an eastward flow at 14°N and northern recirculations from the northern subtropical gyre. The existence of these northern jets explains the greater contribution of North Atlantic CW observed in the lower CW, making up to 50% of the water mass at the naOMZ core. The equatorward transfer of mass from the well-ventilated northern subtropical gyre emerges as an essential part of the ventilation of the naOMZ. © 2015. American Geophysical Union. All Rights Reserved This research has been funded by the Spanish Ministerio de Economía y Competitividad through projects MOC2 (CTM2008–06438-C02-01) and TIC-MOC (CTM2011–28867). J. Peña- Izquierdo has been supported through a FPI predoctoral grant linked to MOC2. E. van Sebille was supported by the Australian Research Council via grant DE130101336 and P. J. Llanillo was partly funded by CONICYT/FONDECYT de Postdoctorado through project 3150229. The authors acknowledge the NODC and Argo Program for making hydrographic ...