Dynamics of Spontaneous (Multi) Centennial-Scale Variations of the Atlantic Meridional Overturning Circulation Strength During the Last Interglacial

A. Kessler; N. Bouttes; D. M. Roche; U. S. Ninnemann; J. Tjiputra

doi:10.1029/2020PA003913

Dynamics of Spontaneous (Multi) Centennial-Scale Variations of the Atlantic Meridional Overturning Circulation Strength During the Last Interglacial

A. Kessler^*, N. Bouttes, D. M. Roche, U. S. Ninnemann, J. Tjiputra

^*Corresponding author for this work

Earth Sciences

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

Recent reconstructions of bottom water δ¹³C during the last interglacial (LIG) suggest short-lived variability in the Atlantic meridional overturning circulation (AMOC). Spontaneous (multi) centennial-scale variability of the AMOC simulated in the Earth system model of intermediate complexity iLOVECLIM are investigated for that period. The model simulates abrupt AMOC transitions occurring at 300 years frequency and correspond to a switch of the AMOC vigor between a strong (∼17 Sv) and a weak (∼11 Sv) state. The onset of these abrupt transitions is associated with changes in orbital forcings resulting in the decline of summer insolation in the high latitudes of the North Atlantic and affecting the sea ice cover in two key deep convection regions: (1) the northern Nordic Seas (NNS) and (2) the northwest North Atlantic (NWNA). Northward inflow of Atlantic surface water increases the convection depth in (1) and strengthens the Greenland Iceland Norway (GIN) Seas overturning circulation. Subsequent ocean-atmosphere interactions involving sea ice, ocean heat release, anomalies of evaporation-precipitation, and wind stress over the Nordic Seas lead also to an increase in deep convection in (2), followed by increase in the AMOC strength.

Original language	English
Article number	e2020PA003913
Pages (from-to)	1-18
Number of pages	18
Journal	Paleoceanography and Paleoclimatology
Volume	35
Issue number	8
Early online date	28 Jul 2020
DOIs	https://doi.org/10.1029/2020PA003913
Publication status	Published - Aug 2020

Funding

This work was supported by the Research Council of Norway funded project THRESHOLDS (254964) and ORGANIC (239965) and Bjerknes Centre for Climate Research project BIGCHANGE. We acknowledge the Norwegian Metacenter for Computational Science and Storage Infrastructure (Notur/Norstore) Projects nn1002k and ns1002k for providing the computing and storing resources essential for this study. We thank Xu Zhang and anonymous reviewer for their constructive feedbacks. We also thank Matthew Huber for the time he dedicated in processing our manuscript and his additional feedback. J. T. also acknowledges funding from Research Council of Norway (Columbia, 275268).

Funders	Funder number
Bjerknes Centre for Climate Research	275268
ORGANIC	239965
Norges forskningsråd	254964

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title = "Dynamics of Spontaneous (Multi) Centennial-Scale Variations of the Atlantic Meridional Overturning Circulation Strength During the Last Interglacial",

abstract = "Recent reconstructions of bottom water δ13C during the last interglacial (LIG) suggest short-lived variability in the Atlantic meridional overturning circulation (AMOC). Spontaneous (multi) centennial-scale variability of the AMOC simulated in the Earth system model of intermediate complexity iLOVECLIM are investigated for that period. The model simulates abrupt AMOC transitions occurring at 300 years frequency and correspond to a switch of the AMOC vigor between a strong (∼17 Sv) and a weak (∼11 Sv) state. The onset of these abrupt transitions is associated with changes in orbital forcings resulting in the decline of summer insolation in the high latitudes of the North Atlantic and affecting the sea ice cover in two key deep convection regions: (1) the northern Nordic Seas (NNS) and (2) the northwest North Atlantic (NWNA). Northward inflow of Atlantic surface water increases the convection depth in (1) and strengthens the Greenland Iceland Norway (GIN) Seas overturning circulation. Subsequent ocean-atmosphere interactions involving sea ice, ocean heat release, anomalies of evaporation-precipitation, and wind stress over the Nordic Seas lead also to an increase in deep convection in (2), followed by increase in the AMOC strength.",

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Dynamics of Spontaneous (Multi) Centennial-Scale Variations of the Atlantic Meridional Overturning Circulation Strength During the Last Interglacial. / Kessler, A.; Bouttes, N.; Roche, D. M. et al.
In: Paleoceanography and Paleoclimatology, Vol. 35, No. 8, e2020PA003913, 08.2020, p. 1-18.

Research output: Contribution to Journal › Article › Academic › peer-review

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Dynamics of Spontaneous (Multi) Centennial-Scale Variations of the Atlantic Meridional Overturning Circulation Strength During the Last Interglacial

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