This dissertation discusses a linkage between the Southern Ocean (SO) winds and
the global ocean circulation in the framework of a coarse-resolution global ocean general
circulation model coupled to a sea-ice model. In addition to reexamination of the
conventional linkage that begins with northward Ekman transport and extends to the
North Atlantic (NA) overturning, the author investigates a new linkage that begins with
the Southern Hemisphere (SH) sea-ice – ocean interaction perturbed by the anomalous
SO winds and extends to the SH overturning, the response of the NA overturning, and the
long-term baroclinic adjustment of the Antarctic Circumpolar Current (ACC). How the
above two linkages will interact with each other in a warming world is also investigated.
An interactive momentum flux forcing, allowing for the strength of momentum
flux between atmosphere and sea ice to vary in response to the simulated sea-ice
conditions, enhances wind-driven ice divergence to increase the fraction of leads and
polynyas, which increases dense water formation, and thus intensifies convection. Within
three experimental frameworks, this increased dense water consistently increases the Antarctic Bottom Water formation, which directly intensifies the SH overturning and
indirectly weakens the NA overturning. As a result of the hemispheric change in
overturning circulations, the meridional density gradient across the ACC appears to
increase, ultimately increasing the baroclinic part of the ACC via an enhanced thermal
wind shear.
Subsequently, impacts of the poleward shifted and intensified SH subpolar
westerly winds (SWWs) on the global ocean circulation are investigated in phases. When
the SWWs are only shifted poleward, the effect of the anomalous winds is transmitted to
the northern NA, decreasing both the NA overturning and the North Atlantic Deep Water
(NADW) outflow. However, when the SWWs are shifted poleward and intensified, this
effect is cut off by the intensified Deacon cell overturning, and is not transmitted to the
northern NA, and instead increases the NADW outflow substantially. To sum up, with
respect to the SO winds perturbed by the global warming, the SH overturning cell and the
NADW outflow increase, leading to an increase in the volume transport of the ACC.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3029 |
| Date | 15 May 2009 |
| Creators | Cheon, Woo Geunn |
| Contributors | St?l, Achim |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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