Water mass pathways to the North Atlantic oxygen minimum zone

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Title: Water mass pathways to the North Atlantic oxygen minimum zone
Authors: Peña-Izquierdo, J
Van Sebille, E
Pelegrí, JL
Sprintall, J
Mason, E
Llanillo, PJ
Machín, F
Item Type: Journal Article
Abstract: © 2015. American Geophysical Union. All Rights Reserved.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<inf>θ</inf> = 26.8 kg m<sup>-3</sup> (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.
Issue Date: 1-May-2015
Date of Acceptance: 30-Mar-2015
ISSN: 2169-9291
Publisher: American Geophysical Union (AGU)
Start Page: 3350
End Page: 3372
Journal / Book Title: Journal of Geophysical Research: Oceans
Volume: 120
Issue: 5
Copyright Statement: © 2015. American Geophysical Union. All Rights Reserved.
Publication Status: Published
Appears in Collections:Centre for Environmental Policy
Faculty of Natural Sciences

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