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Ocean circulation and climate dynamics under idealised continental configurations in a coupled ocean-atmosphere model

Ocean circulation and climate dynamics under idealised continental configurations in a coupled ocean-atmosphere model
Ocean circulation and climate dynamics under idealised continental configurations in a coupled ocean-atmosphere model

A low resolution coupled ocean-atmosphere general circulation model has been developed for studying the characteristics and impact of the large scale oceanic circulation on the climate in a range of theoretical situations.  The model is run with land-shapes significantly different from those present today;  the relatively realistic nature of the component models provides simulations of these theoretical climates and their component feedbacks with a greater degree of confidence than the results of less sophisticated models previously applied to similar cases.  The model is applied to a series of highly idealised configurations:  an aquaplanet with no land at all, a single global basin, a basin with a narrow gap in the lower southern hemisphere allowing throughflow and two scenarios with a Pangea-scale supercontinent - one with a similar gap for zonal flow in the southern hemisphere and one without. 

In the first three cases the model develops very warm climates in accordance with the reduced albedo and highly abundance of water in the atmosphere. The last two cases produce cooler, highly seasonal climates dominated by the response to the land-sea contrast.

Changes in the ocean heat transport are shown to impact both the meridional temperature gradient and the global mean climate produced.  Interactions with the overlying atmosphere result in changes in the system’s radiative properties which significantly alter the mean climate simulated.

When a simple radiative model is fitted to the atmosphere obtained in each case, the characterised parameters are indicative of qualitatively different behaviours for each.  These would not have been reproduced by an EBM-type atmosphere tuned to an a priori state and intuitively scaled by the changed surface characteristics of the scenarios, suggesting that such simpler studies may need to be initially guided by more complete GCM results on a case by case basis.

Significant non-advective heat transport is also found in some cases in the ocean, which compensates for changes in the advective transport.  The strength of these non-advective fluxes and the degree of compensation is dependent on the strength of the greenhouse forcing.

University of Southampton
Smith, Robin Stuart
5bc7ab84-8949-47dd-b4fe-db9cad4fd62f
Smith, Robin Stuart
5bc7ab84-8949-47dd-b4fe-db9cad4fd62f

Smith, Robin Stuart (2004) Ocean circulation and climate dynamics under idealised continental configurations in a coupled ocean-atmosphere model. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

A low resolution coupled ocean-atmosphere general circulation model has been developed for studying the characteristics and impact of the large scale oceanic circulation on the climate in a range of theoretical situations.  The model is run with land-shapes significantly different from those present today;  the relatively realistic nature of the component models provides simulations of these theoretical climates and their component feedbacks with a greater degree of confidence than the results of less sophisticated models previously applied to similar cases.  The model is applied to a series of highly idealised configurations:  an aquaplanet with no land at all, a single global basin, a basin with a narrow gap in the lower southern hemisphere allowing throughflow and two scenarios with a Pangea-scale supercontinent - one with a similar gap for zonal flow in the southern hemisphere and one without. 

In the first three cases the model develops very warm climates in accordance with the reduced albedo and highly abundance of water in the atmosphere. The last two cases produce cooler, highly seasonal climates dominated by the response to the land-sea contrast.

Changes in the ocean heat transport are shown to impact both the meridional temperature gradient and the global mean climate produced.  Interactions with the overlying atmosphere result in changes in the system’s radiative properties which significantly alter the mean climate simulated.

When a simple radiative model is fitted to the atmosphere obtained in each case, the characterised parameters are indicative of qualitatively different behaviours for each.  These would not have been reproduced by an EBM-type atmosphere tuned to an a priori state and intuitively scaled by the changed surface characteristics of the scenarios, suggesting that such simpler studies may need to be initially guided by more complete GCM results on a case by case basis.

Significant non-advective heat transport is also found in some cases in the ocean, which compensates for changes in the advective transport.  The strength of these non-advective fluxes and the degree of compensation is dependent on the strength of the greenhouse forcing.

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Published date: 2004

Identifiers

Local EPrints ID: 465231
URI: http://eprints.soton.ac.uk/id/eprint/465231
PURE UUID: 59bb1dfd-7236-431f-af62-86637ebfb6f1

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Date deposited: 05 Jul 2022 00:30
Last modified: 16 Mar 2024 20:03

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Author: Robin Stuart Smith

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