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Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa
This investigation addresses the thermal characteristics of the major oceanic frontal systems in the Southern Ocean south of Africa based on data collected to a depth of 500 m on forty-three cruises during a fifteen year period. The width of the Agulhas Front has been shown to vary considerably in b...
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| Format: | Thesis |
| Language: | English |
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Department of Oceanography
2020
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| _version_ | 1867613332759904256 |
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| access_status_str | Open Access |
| author | Matthysen, Craig Peter |
| author2 | Lutjeharms, Johann |
| author_browse | Lutjeharms, Johann Matthysen, Craig Peter |
| author_facet | Lutjeharms, Johann Matthysen, Craig Peter |
| author_sort | Matthysen, Craig Peter |
| collection | Thesis |
| description | This investigation addresses the thermal characteristics of the major oceanic frontal systems in the Southern Ocean south of Africa based on data collected to a depth of 500 m on forty-three cruises during a fifteen year period. The width of the Agulhas Front has been shown to vary considerably in both its sea surface and sub-surface thermal manifestation as a result of mesoscale turbulence. Its mean sea surface width of 84 km has a standard deviation of 53 km, and the mean subsurface width of 37 km has a standard deviation of 33 km. The Agulhas Front. has been found to be a separate front north of the Subtropical Convergence in 56 % of the cruises investigated. It has only been observed from 18,2°E to 24,7°E, with a mean sea and subsurface temperature gradient across the Agulhas Front of 0,05 °C/km and 0, 13 °C/km respectively. It has a mean sea surface middle temperature of 17, 8° C and a mean subsurface middle temperature of 12,6° C. The mean sea and sub-surface geographic positions of the thermal expression of the Agulhas Front are 39,3° S; 22,7° E aild 39,1° S; 22,7° E. The Subtropical Convergence at surface has been found to be a single, broad frontal zone across the Central/South East Atlantic Ocean, that does not bifurcate. It has a mean sea surface middle temperature of ·14,3° C and a mean sub-surface middle temperature of 8,4° C. The mean sea and sub-surface temperature gradients across the Subtropical Convergence are O, 03 °C/km and O, 05 °C/km respectively. The mean sea and sub-surface geographic positions of the· thermal expression of the Subtropical Convergence are 41, 8° S; 21, 9° E and 41, 7° S; 22, 0° E. The Subtropical Convergence has a mean sea surface width of 146 km and a mean sub-surface width of 79 km. The Sub-antarctic Front is pressed northward from 45° S to 43° S by the Mid-Ocean Ridge in the South West Indian Ocean sector, after which it converges · with the Subtropical Convergence at approximately 60° E to form a united STC/SAF at subsurface. This united STC/SAF does not however form a "Crozet Front" by joining the Agulhas Front between 52° E and 65° E. It has a mean sea surface middle temperature of 4,4° C and a mean sub-surface middle temperature of 4,0° C. The mean sea and subsurface temperature gradients across the Sub-antarctic Front are 0,02 °C/km. The mean sea and sub-surface geographic positions of the thermal expression of the Sub-antarctic Front are 48,7° S; 18,9° E and 46,8° S; 19,9° E. The Sub-antarctic Front has a mean sea surface width of 73 km and a mean sub-surface width of 77 km. In 30 % of the sections investigated the- Antarctic Polar Front consisted of a primary and secondary front. The Antarctic Polar Front does not join the Sub-antarctic Front east of · 40° E at sub-surface and subsequently no quadruple front is formed. It has a mean sea surface middle temperature of 2, 1 ° C and a mean sub-surface middle temperature of 2,3° C. The mean sea and sub-surface temperature gradients across the Antarctic Polar Front are 0,01 °C/km and 0,02 °C/km respectively. The mean sea and sub-surface geographic position of the thermal expression of the Antarctic Polar Front are 52, 7° S; 14,9° E and 49,2° S; 20,8° E. The Antarctic Polar Front has a mean sea surface width of 66 km and a mean sub-surface width of 74 km. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/31853 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:27.383Z |
| 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:11427/31853 Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa Matthysen, Craig Peter Lutjeharms, Johann thermal characteristics oceanic frontal systems This investigation addresses the thermal characteristics of the major oceanic frontal systems in the Southern Ocean south of Africa based on data collected to a depth of 500 m on forty-three cruises during a fifteen year period. The width of the Agulhas Front has been shown to vary considerably in both its sea surface and sub-surface thermal manifestation as a result of mesoscale turbulence. Its mean sea surface width of 84 km has a standard deviation of 53 km, and the mean subsurface width of 37 km has a standard deviation of 33 km. The Agulhas Front. has been found to be a separate front north of the Subtropical Convergence in 56 % of the cruises investigated. It has only been observed from 18,2°E to 24,7°E, with a mean sea and subsurface temperature gradient across the Agulhas Front of 0,05 °C/km and 0, 13 °C/km respectively. It has a mean sea surface middle temperature of 17, 8° C and a mean subsurface middle temperature of 12,6° C. The mean sea and sub-surface geographic positions of the thermal expression of the Agulhas Front are 39,3° S; 22,7° E aild 39,1° S; 22,7° E. The Subtropical Convergence at surface has been found to be a single, broad frontal zone across the Central/South East Atlantic Ocean, that does not bifurcate. It has a mean sea surface middle temperature of ·14,3° C and a mean sub-surface middle temperature of 8,4° C. The mean sea and sub-surface temperature gradients across the Subtropical Convergence are O, 03 °C/km and O, 05 °C/km respectively. The mean sea and sub-surface geographic positions of the· thermal expression of the Subtropical Convergence are 41, 8° S; 21, 9° E and 41, 7° S; 22, 0° E. The Subtropical Convergence has a mean sea surface width of 146 km and a mean sub-surface width of 79 km. The Sub-antarctic Front is pressed northward from 45° S to 43° S by the Mid-Ocean Ridge in the South West Indian Ocean sector, after which it converges · with the Subtropical Convergence at approximately 60° E to form a united STC/SAF at subsurface. This united STC/SAF does not however form a "Crozet Front" by joining the Agulhas Front between 52° E and 65° E. It has a mean sea surface middle temperature of 4,4° C and a mean sub-surface middle temperature of 4,0° C. The mean sea and subsurface temperature gradients across the Sub-antarctic Front are 0,02 °C/km. The mean sea and sub-surface geographic positions of the thermal expression of the Sub-antarctic Front are 48,7° S; 18,9° E and 46,8° S; 19,9° E. The Sub-antarctic Front has a mean sea surface width of 73 km and a mean sub-surface width of 77 km. In 30 % of the sections investigated the- Antarctic Polar Front consisted of a primary and secondary front. The Antarctic Polar Front does not join the Sub-antarctic Front east of · 40° E at sub-surface and subsequently no quadruple front is formed. It has a mean sea surface middle temperature of 2, 1 ° C and a mean sub-surface middle temperature of 2,3° C. The mean sea and sub-surface temperature gradients across the Antarctic Polar Front are 0,01 °C/km and 0,02 °C/km respectively. The mean sea and sub-surface geographic position of the thermal expression of the Antarctic Polar Front are 52, 7° S; 14,9° E and 49,2° S; 20,8° E. The Antarctic Polar Front has a mean sea surface width of 66 km and a mean sub-surface width of 74 km. 2020-05-12T11:48:42Z 2020-05-12T11:48:42Z 1997 2020-04-02T11:21:12Z Master Thesis Masters https://hdl.handle.net/11427/31853 eng application/pdf Department of Oceanography Faculty of Science |
| spellingShingle | thermal characteristics oceanic frontal systems Matthysen, Craig Peter Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa |
| thesis_degree_str | Master's |
| title | Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa |
| title_full | Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa |
| title_fullStr | Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa |
| title_full_unstemmed | Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa |
| title_short | Detail of the thermal structure of oceanic fronts in the Southern ocean south of Africa |
| title_sort | detail of the thermal structure of oceanic fronts in the southern ocean south of africa |
| topic | thermal characteristics oceanic frontal systems |
| url | https://hdl.handle.net/11427/31853 |
| work_keys_str_mv | AT matthysencraigpeter detailofthethermalstructureofoceanicfrontsinthesouthernoceansouthofafrica |