Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity
The effect of orbital variations on simulated millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) is studied using the earth system model of intermediate complexity LOVECLIM. It is found that for present-day topographic boundary conditions low obliquity values (~22...
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ftcopernicus:oai:publications.copernicus.org:cpd1367 2023-05-15T16:35:21+02:00 Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity Friedrich, T. Timmermann, A. Timm, O. Mouchet, A. Roche, D. M. 2018-09-26 application/pdf https://doi.org/10.5194/cpd-5-2019-2009 https://cp.copernicus.org/preprints/cp-2009-48/ eng eng doi:10.5194/cpd-5-2019-2009 https://cp.copernicus.org/preprints/cp-2009-48/ eISSN: 1814-9332 Text 2018 ftcopernicus https://doi.org/10.5194/cpd-5-2019-2009 2020-07-20T16:26:37Z The effect of orbital variations on simulated millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) is studied using the earth system model of intermediate complexity LOVECLIM. It is found that for present-day topographic boundary conditions low obliquity values (~22.1°) favor the triggering of internally generated millennial-scale variability in the North Atlantic region. Reducing the obliquity leads to changes of the pause-pulse ratio of the corresponding AMOC oscillations. Stochastic excitations of the density-driven overturning circulation in the Nordic Seas can create regional sea-ice anomalies and a subsequent reorganization of the atmospheric circulation. The resulting remote atmospheric anomalies over the Hudson Bay can release freshwater pulses into the Labrador Sea leading to a subsequent reduction of convective activity. The millennial-scale AMOC oscillations disappear if LGM bathymetry (with closed Hudson Bay) is prescribed. Furthermore, our study documents the marine and terrestrial carbon cycle response to millennial-scale AMOC variability. Our model results support the notion that stadial regimes in the North Atlantic are accompanied by relatively high levels of oxygen in thermocline and intermediate waters off California – in agreement with paleo-proxy data. Text Hudson Bay Labrador Sea Nordic Seas North Atlantic Sea ice Copernicus Publications: E-Journals Hudson Hudson Bay |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The effect of orbital variations on simulated millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) is studied using the earth system model of intermediate complexity LOVECLIM. It is found that for present-day topographic boundary conditions low obliquity values (~22.1°) favor the triggering of internally generated millennial-scale variability in the North Atlantic region. Reducing the obliquity leads to changes of the pause-pulse ratio of the corresponding AMOC oscillations. Stochastic excitations of the density-driven overturning circulation in the Nordic Seas can create regional sea-ice anomalies and a subsequent reorganization of the atmospheric circulation. The resulting remote atmospheric anomalies over the Hudson Bay can release freshwater pulses into the Labrador Sea leading to a subsequent reduction of convective activity. The millennial-scale AMOC oscillations disappear if LGM bathymetry (with closed Hudson Bay) is prescribed. Furthermore, our study documents the marine and terrestrial carbon cycle response to millennial-scale AMOC variability. Our model results support the notion that stadial regimes in the North Atlantic are accompanied by relatively high levels of oxygen in thermocline and intermediate waters off California – in agreement with paleo-proxy data. |
format |
Text |
author |
Friedrich, T. Timmermann, A. Timm, O. Mouchet, A. Roche, D. M. |
spellingShingle |
Friedrich, T. Timmermann, A. Timm, O. Mouchet, A. Roche, D. M. Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
author_facet |
Friedrich, T. Timmermann, A. Timm, O. Mouchet, A. Roche, D. M. |
author_sort |
Friedrich, T. |
title |
Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
title_short |
Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
title_full |
Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
title_fullStr |
Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
title_full_unstemmed |
Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
title_sort |
orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity |
publishDate |
2018 |
url |
https://doi.org/10.5194/cpd-5-2019-2009 https://cp.copernicus.org/preprints/cp-2009-48/ |
geographic |
Hudson Hudson Bay |
geographic_facet |
Hudson Hudson Bay |
genre |
Hudson Bay Labrador Sea Nordic Seas North Atlantic Sea ice |
genre_facet |
Hudson Bay Labrador Sea Nordic Seas North Atlantic Sea ice |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cpd-5-2019-2009 https://cp.copernicus.org/preprints/cp-2009-48/ |
op_doi |
https://doi.org/10.5194/cpd-5-2019-2009 |
_version_ |
1766025570931441664 |