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: | Master Thesis |
| Language: | English |
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Faculty of Science
1997
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| Online Access: | https://hdl.handle.net/11427/31853 https://open.uct.ac.za/bitstream/11427/31853/1/thesis_sci_1997_matthysen_craig_peter.pdf |
| Summary: | 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 ... |
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