The University of Southampton
University of Southampton Institutional Repository

Effects of atmospheric dynamics and ocean resolution on bi-stability of the thermohaline circulation examined using the Grid ENabled Integrated Earth system modelling (GENIE) framework

Effects of atmospheric dynamics and ocean resolution on bi-stability of the thermohaline circulation examined using the Grid ENabled Integrated Earth system modelling (GENIE) framework
Effects of atmospheric dynamics and ocean resolution on bi-stability of the thermohaline circulation examined using the Grid ENabled Integrated Earth system modelling (GENIE) framework
We have used the Grid ENabled Integrated Earth system modelling (GENIE) framework to undertake a systematic search for bi-stability of the ocean thermohaline circulation (THC) for different surface grids and resolutions of 3-D ocean (GOLDSTEIN) under a 3-D dynamical atmosphere model (IGCM). A total of 407,000 years were simulated over a three month period using Grid computing. We find bi-stability of the THC despite significant, quasi-periodic variability in its strength driven by variability in the dynamical atmosphere. The position and width of the hysteresis loop depends on the choice of surface grid (longitude-latitude or equal area), but is less sensitive to changes in ocean resolution. For the same ocean resolution, the region of bi-stability is broader with the IGCM than with a simple energy-moisture balance atmosphere model (EMBM). Feedbacks involving both ocean and atmospheric dynamics are found to promote THC bi-stability. THC switch-off leads to increased import of freshwater at the southern boundary of the Atlantic associated with meridional overturning circulation. This is counteracted by decreased freshwater import associated with gyre and diffusive transports. However, these are localised such that the density gradient between North and South is reduced tending to maintain the THC off state. THC switch-off can also generate net atmospheric freshwater input to the Atlantic that tends to maintain the off state. The ocean feedbacks are present in all resolutions, across most of the bi-stable region, whereas the atmosphere feedback is strongest in the longitude–latitude grid and around the transition where the THC off state is disappearing. Here the net oceanic freshwater import due to the overturning mode weakens, promoting THC switch-on, but the atmosphere counteracts this by increasing net freshwater input. This increases the extent of THC bi-stability in this version of the model.
0930-7575
591-613
Lenton, T.M.
f2b4fe3d-ef5e-4c85-9677-bfc20c266b65
Marsh, R.
702c2e7e-ac19-4019-abd9-a8614ab27717
Price, A.R.
15a6667c-60da-42e9-b6dd-4c0e56c33c52
Lunt, D.J.
5bfca8db-49a7-45dd-9855-43606a58788b
Aksenov, Y.
1d277047-06f6-4893-8bcf-c2817a9c848e
Annan, J.D.
dfa1bdc7-bf41-409c-960c-1d96adca782e
Cooper-Chadwick, T.
acb9c8a0-e0b6-4677-93ca-16a262c0bd50
Cox, S.J.
0e62aaed-24ad-4a74-b996-f606e40e5c55
Edwards, N.R.
e41b719b-784e-4748-acc4-6ccbc4643c7d
Goswami, S.
0799841f-4031-4050-b5ec-54fe0faa9db9
Hargreaves, J.C.
a6d5e120-16b7-4473-a8ac-9c0b96f27939
Harris, P.P.
2637209b-3059-4284-a377-4f54ad61b01d
Jiao, Z.
6d4dd027-f745-4b35-b701-e10b45b50be1
Livina, V.N.
387c88da-9a83-4d1b-80d1-9575cade3ae9
Payne, A.J.
ce816e45-23ce-4805-a987-ab26e17b3bab
Rutt, I.C.
c02e80c1-edbc-4f64-997c-97ce85f4ab6a
Shepherd, J.G.
f38de3ac-eb3b-403f-8767-c76be68d8bf2
Valdes, P.J.
7b271d19-a4cb-4fc3-af4e-6745239c01d8
Williams, G.
7e38985a-981b-4f64-8c33-9c0854a199e3
Williamson, M.S.
4d517b9a-3893-41af-887f-c6fb7b62ab58
Yool, A.
882aeb0d-dda0-405e-844c-65b68cce5017
Lenton, T.M.
f2b4fe3d-ef5e-4c85-9677-bfc20c266b65
Marsh, R.
702c2e7e-ac19-4019-abd9-a8614ab27717
Price, A.R.
15a6667c-60da-42e9-b6dd-4c0e56c33c52
Lunt, D.J.
5bfca8db-49a7-45dd-9855-43606a58788b
Aksenov, Y.
1d277047-06f6-4893-8bcf-c2817a9c848e
Annan, J.D.
dfa1bdc7-bf41-409c-960c-1d96adca782e
Cooper-Chadwick, T.
acb9c8a0-e0b6-4677-93ca-16a262c0bd50
Cox, S.J.
0e62aaed-24ad-4a74-b996-f606e40e5c55
Edwards, N.R.
e41b719b-784e-4748-acc4-6ccbc4643c7d
Goswami, S.
0799841f-4031-4050-b5ec-54fe0faa9db9
Hargreaves, J.C.
a6d5e120-16b7-4473-a8ac-9c0b96f27939
Harris, P.P.
2637209b-3059-4284-a377-4f54ad61b01d
Jiao, Z.
6d4dd027-f745-4b35-b701-e10b45b50be1
Livina, V.N.
387c88da-9a83-4d1b-80d1-9575cade3ae9
Payne, A.J.
ce816e45-23ce-4805-a987-ab26e17b3bab
Rutt, I.C.
c02e80c1-edbc-4f64-997c-97ce85f4ab6a
Shepherd, J.G.
f38de3ac-eb3b-403f-8767-c76be68d8bf2
Valdes, P.J.
7b271d19-a4cb-4fc3-af4e-6745239c01d8
Williams, G.
7e38985a-981b-4f64-8c33-9c0854a199e3
Williamson, M.S.
4d517b9a-3893-41af-887f-c6fb7b62ab58
Yool, A.
882aeb0d-dda0-405e-844c-65b68cce5017

Lenton, T.M., Marsh, R., Price, A.R., Lunt, D.J., Aksenov, Y., Annan, J.D., Cooper-Chadwick, T., Cox, S.J., Edwards, N.R., Goswami, S., Hargreaves, J.C., Harris, P.P., Jiao, Z., Livina, V.N., Payne, A.J., Rutt, I.C., Shepherd, J.G., Valdes, P.J., Williams, G., Williamson, M.S. and Yool, A. (2007) Effects of atmospheric dynamics and ocean resolution on bi-stability of the thermohaline circulation examined using the Grid ENabled Integrated Earth system modelling (GENIE) framework. Climate Dynamics, 29 (6), 591-613. (doi:10.1007/s00382-007-0254-9).

Record type: Article

Abstract

We have used the Grid ENabled Integrated Earth system modelling (GENIE) framework to undertake a systematic search for bi-stability of the ocean thermohaline circulation (THC) for different surface grids and resolutions of 3-D ocean (GOLDSTEIN) under a 3-D dynamical atmosphere model (IGCM). A total of 407,000 years were simulated over a three month period using Grid computing. We find bi-stability of the THC despite significant, quasi-periodic variability in its strength driven by variability in the dynamical atmosphere. The position and width of the hysteresis loop depends on the choice of surface grid (longitude-latitude or equal area), but is less sensitive to changes in ocean resolution. For the same ocean resolution, the region of bi-stability is broader with the IGCM than with a simple energy-moisture balance atmosphere model (EMBM). Feedbacks involving both ocean and atmospheric dynamics are found to promote THC bi-stability. THC switch-off leads to increased import of freshwater at the southern boundary of the Atlantic associated with meridional overturning circulation. This is counteracted by decreased freshwater import associated with gyre and diffusive transports. However, these are localised such that the density gradient between North and South is reduced tending to maintain the THC off state. THC switch-off can also generate net atmospheric freshwater input to the Atlantic that tends to maintain the off state. The ocean feedbacks are present in all resolutions, across most of the bi-stable region, whereas the atmosphere feedback is strongest in the longitude–latitude grid and around the transition where the THC off state is disappearing. Here the net oceanic freshwater import due to the overturning mode weakens, promoting THC switch-on, but the atmosphere counteracts this by increasing net freshwater input. This increases the extent of THC bi-stability in this version of the model.

Text
Lenton_etal_final.pdf - Accepted Manuscript
Download (794kB)

More information

Submitted date: 27 July 2006
Published date: 17 July 2007

Identifiers

Local EPrints ID: 44749
URI: http://eprints.soton.ac.uk/id/eprint/44749
ISSN: 0930-7575
PURE UUID: 7ea9fc75-75e4-411c-926f-357b44306833
ORCID for J.G. Shepherd: ORCID iD orcid.org/0000-0002-5230-4781

Catalogue record

Date deposited: 12 Mar 2007
Last modified: 03 Dec 2019 02:02

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×