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Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations
The Agulhas Current is the strongest Western Boundary Current of the Southern Hemisphere and it plays a significant role in the circulation of the shelf and coastal waters, whereby mesoscale (50- 500 km) and submesoscale (1 -10 km) instabilities in the Agulhas Current impact the local oceanography o...
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| Format: | Thesis |
| Language: | English |
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Department of Oceanography
2020
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| _version_ | 1867613166082457600 |
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| access_status_str | Open Access |
| author | Maja, Tumelo |
| author2 | Krug, Marjolaine |
| author_browse | Krug, Marjolaine Maja, Tumelo |
| author_facet | Krug, Marjolaine Maja, Tumelo |
| author_sort | Maja, Tumelo |
| collection | Thesis |
| description | The Agulhas Current is the strongest Western Boundary Current of the Southern Hemisphere and it plays a significant role in the circulation of the shelf and coastal waters, whereby mesoscale (50- 500 km) and submesoscale (1 -10 km) instabilities in the Agulhas Current impact the local oceanography of the shelf region. The main objective of this study is to evaluate the ability of a gap-free and merged gridded satellite ocean current dataset, GlobCurrent, to resolve and monitor the variability of the Agulhas Current’s cross-shelf dynamics. In this study, GlobCurrent is compared to in-situ observations collected from underwater gliders through mapping and correlation analysis to assess the product’s accuracy in different subdomains and water depths of the Agulhas Current’s main area domain. We also investigate the value of using a higher resolution satellite and gap-free Sea Surface Temperature (SST) dataset to complement the GlobCurrent dataset in observing the Agulhas Current’s flow processes and features. The results show that GlobCurrent is adequate for describing large mesoscale features and deep water flows but the product has limitations in capturing fast-evolving and small mesoscale features, particularly the Durban Eddy in the KZN bight region. GlobCurrent also exhibits, at times, directional errors in addition to the current speed discrepancies. This research study demonstrates the limitation of the GlobCurrent product for monitoring ocean current variability in shallow, coastal waters and regions dominated by small mesoscale variability. This study also provides new insights on the joint use of other merged satellite products i.e. merged ODYSSEA SST, which may compensate for some of the GlobCurrent product’s shortfalls. Future studies should consider complementing altimetry-based satellite products like GlobCurrent with other merged satellite observation products such as ODYSSEA SST for better imaging of small mesoscale processes and features in shallow coastal waters. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/31807 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:48.735Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Department of Oceanography |
| publisherStr | Department of Oceanography |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/31807 Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations Maja, Tumelo Krug, Marjolaine Rouault, Mathieu Johannessen, Johnny A Oceanography The Agulhas Current is the strongest Western Boundary Current of the Southern Hemisphere and it plays a significant role in the circulation of the shelf and coastal waters, whereby mesoscale (50- 500 km) and submesoscale (1 -10 km) instabilities in the Agulhas Current impact the local oceanography of the shelf region. The main objective of this study is to evaluate the ability of a gap-free and merged gridded satellite ocean current dataset, GlobCurrent, to resolve and monitor the variability of the Agulhas Current’s cross-shelf dynamics. In this study, GlobCurrent is compared to in-situ observations collected from underwater gliders through mapping and correlation analysis to assess the product’s accuracy in different subdomains and water depths of the Agulhas Current’s main area domain. We also investigate the value of using a higher resolution satellite and gap-free Sea Surface Temperature (SST) dataset to complement the GlobCurrent dataset in observing the Agulhas Current’s flow processes and features. The results show that GlobCurrent is adequate for describing large mesoscale features and deep water flows but the product has limitations in capturing fast-evolving and small mesoscale features, particularly the Durban Eddy in the KZN bight region. GlobCurrent also exhibits, at times, directional errors in addition to the current speed discrepancies. This research study demonstrates the limitation of the GlobCurrent product for monitoring ocean current variability in shallow, coastal waters and regions dominated by small mesoscale variability. This study also provides new insights on the joint use of other merged satellite products i.e. merged ODYSSEA SST, which may compensate for some of the GlobCurrent product’s shortfalls. Future studies should consider complementing altimetry-based satellite products like GlobCurrent with other merged satellite observation products such as ODYSSEA SST for better imaging of small mesoscale processes and features in shallow coastal waters. 2020-05-06T11:48:15Z 2020-05-06T11:48:15Z 2019 2020-05-06T01:42:34Z Master Thesis Masters MSc https://hdl.handle.net/11427/31807 eng application/pdf Department of Oceanography Faculty of Science |
| spellingShingle | Oceanography Maja, Tumelo Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations |
| thesis_degree_str | Master's |
| title | Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations |
| title_full | Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations |
| title_fullStr | Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations |
| title_full_unstemmed | Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations |
| title_short | Resolving cross-shelf dynamics in the Agulhas Current from GlobCurrent and glider observations |
| title_sort | resolving cross shelf dynamics in the agulhas current from globcurrent and glider observations |
| topic | Oceanography |
| url | https://hdl.handle.net/11427/31807 |
| work_keys_str_mv | AT majatumelo resolvingcrossshelfdynamicsintheagulhascurrentfromglobcurrentandgliderobservations |