Diffusion controls the ventilation of a Pacific Shadow Zone above abyssal overturning - Sorbonne Université Access content directly
Journal Articles Nature Communications Year : 2021

Diffusion controls the ventilation of a Pacific Shadow Zone above abyssal overturning

Abstract

Mid-depth North Pacific waters are rich in nutrients and respired carbon accumulated over centuries. The rates and pathways with which these waters exchange with the surface ocean are uncertain, with divergent paradigms of the Pacific overturning: one envisions bottom waters upwelling to 1.5 km depth; the other confines overturning beneath a mid-depth Pacific shadow zone (PSZ) shielded from mean advection. Here global inverse modelling reveals a PSZ where mean ages exceed 1400 years with overturning beneath. The PSZ is supplied primarily by Antarctic and North-Atlantic ventilated waters diffusing from below and from the south. Half of PSZ waters re-surface in the Southern Ocean, a quarter in the subarctic Pacific. The abyssal North Pacific, despite strong overturning, has mean re-surfacing times also exceeding 1400 years because of diffusion into the overlying PSZ. These results imply that diffusive transportsdistinct from overturning transportsare a leading control on Pacific nutrient and carbon storage.
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Dates and versions

hal-03290349 , version 1 (19-07-2021)

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Cite

Mark Holzer, Tim Devries, Casimir de Lavergne. Diffusion controls the ventilation of a Pacific Shadow Zone above abyssal overturning. Nature Communications, 2021, 12 (1), pp.4348. ⟨10.1038/s41467-021-24648-x⟩. ⟨hal-03290349⟩
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