Demons in the North Atlantic: variability of deep ocean ventilation

G. A. MacGilchrist; H. L. Johnson; C. Lique; D. P. Marshall

doi:10.1029/2020GL092340

Demons in the North Atlantic: variability of deep ocean ventilation

G. A. MacGilchrist^*, H. L. Johnson, C. Lique, D. P. Marshall

^*Corresponding author for this work

School of Earth & Environmental Sciences

Research output: Contribution to journal › Article › peer-review

Abstract

Translation of atmospheric forcing variability into the ocean interior via ocean ventilation is an important aspect of transient climate change. On a seasonal timescale in the subtropics, this translation is mediated by a so-called "Demon" that prevents access to all except late-winter mixed-layer water. Here, we use an eddy-permitting numerical circulation model to investigate a similar process operating on longer (interannual) timescales in the subpolar North Atlantic. We find that variations in atmospheric forcing are mediated in their translation to the ocean interior, with year-to-year changes in the late-winter mixed layer depth being the critical factor. The signature of persistent strong atmospheric forcing driving deep mixed layers is preferentially ventilated to the interior when the forcing is ceased. Susceptibility to this effect depends on the location and density of subduction-with the rate at which newly ventilated water escapes its region of subduction being the crucial factor.

Original language	English
Article number	e2020GL092340
Number of pages	9
Journal	Geophysical Research Letters
Volume	48
Issue number	9
Early online date	29 Apr 2021
DOIs	https://doi.org/10.1029/2020GL092340
Publication status	Published - 16 May 2021

Keywords

Dense water formation
Labrador Sea
Lagrangian
North Atlantic
Ocean mixed layer
Ocean ventilation

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1029/2020GL092340

MacGilchrist_2021_GRL_Demons-NAOcean_VoR
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Demons in the North Atlantic: Variability of Deep Ocean Ventilation (Code)
MacGilchrist, G. (Creator), GitHub, 2022
https://github.com/gmacgilchrist/nadw and one more link, https://github.com/gmacgilchrist/draw_figs_nadw_var (show fewer)
Dataset: Software

Cite this

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title = "Demons in the North Atlantic: variability of deep ocean ventilation",

abstract = "Translation of atmospheric forcing variability into the ocean interior via ocean ventilation is an important aspect of transient climate change. On a seasonal timescale in the subtropics, this translation is mediated by a so-called {"}Demon{"} that prevents access to all except late-winter mixed-layer water. Here, we use an eddy-permitting numerical circulation model to investigate a similar process operating on longer (interannual) timescales in the subpolar North Atlantic. We find that variations in atmospheric forcing are mediated in their translation to the ocean interior, with year-to-year changes in the late-winter mixed layer depth being the critical factor. The signature of persistent strong atmospheric forcing driving deep mixed layers is preferentially ventilated to the interior when the forcing is ceased. Susceptibility to this effect depends on the location and density of subduction-with the rate at which newly ventilated water escapes its region of subduction being the crucial factor.",

keywords = "Dense water formation, Labrador Sea, Lagrangian, North Atlantic, Ocean mixed layer, Ocean ventilation",

author = "MacGilchrist, {G. A.} and Johnson, {H. L.} and C. Lique and Marshall, {D. P.}",

note = "G. A. MacGilchrist is supported through NSF{\textquoteright}s Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project under the NSF Award PLR-1425989, with additional support from NOAA and NASA. HJ and DM were supported by the UK Natural Environment Research Council OSNAP project (NE/K010948/1). C. Lique was supported by the project MEDLEY funded by JPI Climate and JPI Oceans, under the agreement ANR-19-JPOC-0001. The hindcast was carried out within the European Drakkar project.",

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T2 - variability of deep ocean ventilation

AU - MacGilchrist, G. A.

AU - Johnson, H. L.

AU - Lique, C.

AU - Marshall, D. P.

N1 - G. A. MacGilchrist is supported through NSF’s Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project under the NSF Award PLR-1425989, with additional support from NOAA and NASA. HJ and DM were supported by the UK Natural Environment Research Council OSNAP project (NE/K010948/1). C. Lique was supported by the project MEDLEY funded by JPI Climate and JPI Oceans, under the agreement ANR-19-JPOC-0001. The hindcast was carried out within the European Drakkar project.

PY - 2021/5/16

Y1 - 2021/5/16

N2 - Translation of atmospheric forcing variability into the ocean interior via ocean ventilation is an important aspect of transient climate change. On a seasonal timescale in the subtropics, this translation is mediated by a so-called "Demon" that prevents access to all except late-winter mixed-layer water. Here, we use an eddy-permitting numerical circulation model to investigate a similar process operating on longer (interannual) timescales in the subpolar North Atlantic. We find that variations in atmospheric forcing are mediated in their translation to the ocean interior, with year-to-year changes in the late-winter mixed layer depth being the critical factor. The signature of persistent strong atmospheric forcing driving deep mixed layers is preferentially ventilated to the interior when the forcing is ceased. Susceptibility to this effect depends on the location and density of subduction-with the rate at which newly ventilated water escapes its region of subduction being the crucial factor.

AB - Translation of atmospheric forcing variability into the ocean interior via ocean ventilation is an important aspect of transient climate change. On a seasonal timescale in the subtropics, this translation is mediated by a so-called "Demon" that prevents access to all except late-winter mixed-layer water. Here, we use an eddy-permitting numerical circulation model to investigate a similar process operating on longer (interannual) timescales in the subpolar North Atlantic. We find that variations in atmospheric forcing are mediated in their translation to the ocean interior, with year-to-year changes in the late-winter mixed layer depth being the critical factor. The signature of persistent strong atmospheric forcing driving deep mixed layers is preferentially ventilated to the interior when the forcing is ceased. Susceptibility to this effect depends on the location and density of subduction-with the rate at which newly ventilated water escapes its region of subduction being the crucial factor.

KW - Dense water formation

KW - Labrador Sea

KW - Lagrangian

KW - North Atlantic

KW - Ocean mixed layer

KW - Ocean ventilation

U2 - 10.1029/2020GL092340

DO - 10.1029/2020GL092340

M3 - Article

SN - 0094-8276

VL - 48

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 9

M1 - e2020GL092340

ER -

Demons in the North Atlantic: variability of deep ocean ventilation

Abstract

Keywords

UN SDGs

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Demons in the North Atlantic: Variability of Deep Ocean Ventilation (Code)

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