Insights into decadal North Atlantic sea surface temperature and ocean heat content variability from an eddy-permitting coupled climate model
Insights into decadal North Atlantic sea surface temperature and ocean heat content variability from an eddy-permitting coupled climate model
An ocean mixed layer heat budget methodology is used to investigate the physical processes determining subpolar North Atlantic (SPNA) sea surface temperature (SST) and ocean heat content (OHC) variability on decadal-multidecadal timescales using the state-of-the-art climate model HadGEM3-GC2. New elements include development of an equation for evolution of anomalous SST for interannual and longer timescales in a form analogous to that for OHC, parameterization of the diffusive heat flux at the base of the mixed layer and analysis of a composite AMOC event. Contributions to OHC and SST variability from two sources are evaluated i) net ocean-atmosphere heat flux and ii) all other processes, including advection, diffusion and entrainment for SST. Anomalies in OHC tendency propagate anticlockwise around the SPNA on multidecadal timescales with a clear relationship to the phase of the Atlantic meridional overturning circulation (AMOC). AMOC anomalies lead SST tendencies which in turn lead OHC tendencies in both the eastern and western SPNA. OHC and SST variations in the SPNA on decadal timescales are dominated by AMOC variability because it controls variability of advection which is shown to be the dominant term in the OHC budget. Lags between OHC and SST is traced to differences between the advection term for OHC and the advection-entrainment term for SST. The new results have implications for interpretation of variations in Atlantic heat uptake in the CMIP6 climate model assessment.
Moat, B. I.
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Sinha, B.
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Josey, S. A.
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Robson, J.
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Ortega, P.
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Sévellec, F.
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Holliday, N. P.
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Mccarthy, G. D.
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New, A. L.
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Hirschi, J. J.-m.
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Moat, B. I.
497dbb18-a98f-466b-b459-aa2c872ad2dc
Sinha, B.
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Josey, S. A.
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Robson, J.
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Ortega, P.
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Sévellec, F.
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Holliday, N. P.
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Mccarthy, G. D.
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New, A. L.
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Hirschi, J. J.-m.
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Moat, B. I., Sinha, B., Josey, S. A., Robson, J., Ortega, P., Sévellec, F., Holliday, N. P., Mccarthy, G. D., New, A. L. and Hirschi, J. J.-m.
(2019)
Insights into decadal North Atlantic sea surface temperature and ocean heat content variability from an eddy-permitting coupled climate model.
Journal of Climate.
(doi:10.1175/JCLI-D-18-0709.1).
Abstract
An ocean mixed layer heat budget methodology is used to investigate the physical processes determining subpolar North Atlantic (SPNA) sea surface temperature (SST) and ocean heat content (OHC) variability on decadal-multidecadal timescales using the state-of-the-art climate model HadGEM3-GC2. New elements include development of an equation for evolution of anomalous SST for interannual and longer timescales in a form analogous to that for OHC, parameterization of the diffusive heat flux at the base of the mixed layer and analysis of a composite AMOC event. Contributions to OHC and SST variability from two sources are evaluated i) net ocean-atmosphere heat flux and ii) all other processes, including advection, diffusion and entrainment for SST. Anomalies in OHC tendency propagate anticlockwise around the SPNA on multidecadal timescales with a clear relationship to the phase of the Atlantic meridional overturning circulation (AMOC). AMOC anomalies lead SST tendencies which in turn lead OHC tendencies in both the eastern and western SPNA. OHC and SST variations in the SPNA on decadal timescales are dominated by AMOC variability because it controls variability of advection which is shown to be the dominant term in the OHC budget. Lags between OHC and SST is traced to differences between the advection term for OHC and the advection-entrainment term for SST. The new results have implications for interpretation of variations in Atlantic heat uptake in the CMIP6 climate model assessment.
Text
Moat_et_al_2019_J_Climate_rev2_FINAL
- Accepted Manuscript
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Accepted/In Press date: 14 June 2019
e-pub ahead of print date: 14 June 2019
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Local EPrints ID: 431890
URI: http://eprints.soton.ac.uk/id/eprint/431890
ISSN: 0894-8755
PURE UUID: c4082068-0d37-4713-b70a-679c40e10a52
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Date deposited: 20 Jun 2019 16:30
Last modified: 16 Mar 2024 07:56
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Contributors
Author:
B. I. Moat
Author:
B. Sinha
Author:
S. A. Josey
Author:
J. Robson
Author:
P. Ortega
Author:
N. P. Holliday
Author:
G. D. Mccarthy
Author:
A. L. New
Author:
J. J.-m. Hirschi
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