How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models?
Given the importance of the Southern Ocean for the global climate, a realistic representation of the dynamics and circulation in this region in climate models is essential for enhancing confidence in model projections. In this thesis, we investigate the effect of increased horizontal ocean resolutio...
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ftoceanrep:oai:oceanrep.geomar.de:56735 2023-05-15T14:09:12+02:00 How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? Noack, Julia 2022-07 text https://oceanrep.geomar.de/id/eprint/56735/ https://oceanrep.geomar.de/id/eprint/56735/1/Noack_Bachelor_2022.pdf en eng https://oceanrep.geomar.de/id/eprint/56735/1/Noack_Bachelor_2022.pdf Noack, J. (2022) How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models?. (Bachelor thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 39 pp. info:eu-repo/semantics/closedAccess Course of study: BSc Physics of the Earth System Thesis NonPeerReviewed 2022 ftoceanrep 2023-04-07T16:03:51Z Given the importance of the Southern Ocean for the global climate, a realistic representation of the dynamics and circulation in this region in climate models is essential for enhancing confidence in model projections. In this thesis, we investigate the effect of increased horizontal ocean resolution and associated more explicitly resolved mesoscale ocean dynamics on the Antarctic Circumpolar Current (ACC) strength in two coupled climate models. We consider a medium and high-resolution version of FOCI (1/2° and 1/10°) and two versions of HadGEM with a 1/4° and 1/12° ocean resolution in our analysis. With a mean Drake Passage transport of 151 Sv and 115 Sv both high-resolution versions show a significantly better representation of the ACC strength that is closer to observational estimates than their respective coarser-resolution version with lower mean transports of 78 Sv and 80 Sv. The bias between the different resolution models is found to be related to the horizontal structure of the ACC displayed in each model. The medium-resolution versions exhibit several strong countercurrents causing an overall weaker ACC strength. These westward currents are not simulated to this extent in the high-resolution versions and are not proven by observations. Variations in the meridional density gradient found between the models partly explain the difference in the flow as implied by the thermal wind relation. The density differences in turn can be traced back to a stronger salinity gradient in the high-resolution models. Furthermore, we also show that the transport bias between the different resolution simulations in FOCI only starts to build up after several decades of model run length while initially both resolution versions have very similar and high transports. This can be linked to an increasingly different density stratification due to a stronger temperature gradient and a more saline Antarctic continental shelf in the high-resolution simulation after several decades of the model run. Furthermore, bathymetry is also ... Thesis Antarc* Antarctic Drake Passage Southern Ocean OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Antarctic Drake Passage Southern Ocean The Antarctic |
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OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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English |
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Course of study: BSc Physics of the Earth System |
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Course of study: BSc Physics of the Earth System Noack, Julia How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? |
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Course of study: BSc Physics of the Earth System |
description |
Given the importance of the Southern Ocean for the global climate, a realistic representation of the dynamics and circulation in this region in climate models is essential for enhancing confidence in model projections. In this thesis, we investigate the effect of increased horizontal ocean resolution and associated more explicitly resolved mesoscale ocean dynamics on the Antarctic Circumpolar Current (ACC) strength in two coupled climate models. We consider a medium and high-resolution version of FOCI (1/2° and 1/10°) and two versions of HadGEM with a 1/4° and 1/12° ocean resolution in our analysis. With a mean Drake Passage transport of 151 Sv and 115 Sv both high-resolution versions show a significantly better representation of the ACC strength that is closer to observational estimates than their respective coarser-resolution version with lower mean transports of 78 Sv and 80 Sv. The bias between the different resolution models is found to be related to the horizontal structure of the ACC displayed in each model. The medium-resolution versions exhibit several strong countercurrents causing an overall weaker ACC strength. These westward currents are not simulated to this extent in the high-resolution versions and are not proven by observations. Variations in the meridional density gradient found between the models partly explain the difference in the flow as implied by the thermal wind relation. The density differences in turn can be traced back to a stronger salinity gradient in the high-resolution models. Furthermore, we also show that the transport bias between the different resolution simulations in FOCI only starts to build up after several decades of model run length while initially both resolution versions have very similar and high transports. This can be linked to an increasingly different density stratification due to a stronger temperature gradient and a more saline Antarctic continental shelf in the high-resolution simulation after several decades of the model run. Furthermore, bathymetry is also ... |
format |
Thesis |
author |
Noack, Julia |
author_facet |
Noack, Julia |
author_sort |
Noack, Julia |
title |
How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? |
title_short |
How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? |
title_full |
How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? |
title_fullStr |
How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? |
title_full_unstemmed |
How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models? |
title_sort |
how do mesoscale ocean dynamics affect antarctic circumpolar current strength in climate models? |
publishDate |
2022 |
url |
https://oceanrep.geomar.de/id/eprint/56735/ https://oceanrep.geomar.de/id/eprint/56735/1/Noack_Bachelor_2022.pdf |
geographic |
Antarctic Drake Passage Southern Ocean The Antarctic |
geographic_facet |
Antarctic Drake Passage Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Drake Passage Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage Southern Ocean |
op_relation |
https://oceanrep.geomar.de/id/eprint/56735/1/Noack_Bachelor_2022.pdf Noack, J. (2022) How do mesoscale ocean dynamics affect Antarctic Circumpolar Current strength in climate models?. (Bachelor thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 39 pp. |
op_rights |
info:eu-repo/semantics/closedAccess |
_version_ |
1766281209992708096 |