Agulhas retroflection rings in the South Atlantic Ocean
The western boundary current rings shed from the Agulhas retroflection may be responsible for a considerable transfer of heat, salt and energy from the South Indian into the South Atlantic Ocean. Few hydrographic measurements have been collected from Agulhas rings in the South Atlantic Ocean and the...
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Language: | English |
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University of Cape Town
1994
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Online Access: | http://hdl.handle.net/11427/18340 https://open.uct.ac.za/bitstream/11427/18340/1/thesis_sci_1994_duncombe_rae_christopher_michael.pdf |
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ftunivcapetownir:oai:localhost:11427/18340 2023-05-15T18:20:38+02:00 Agulhas retroflection rings in the South Atlantic Ocean Duncombe Rae, Christopher Michael Shillington, Frank A 1994 application/pdf http://hdl.handle.net/11427/18340 https://open.uct.ac.za/bitstream/11427/18340/1/thesis_sci_1994_duncombe_rae_christopher_michael.pdf eng eng University of Cape Town Faculty of Science Department of Oceanography http://hdl.handle.net/11427/18340 https://open.uct.ac.za/bitstream/11427/18340/1/thesis_sci_1994_duncombe_rae_christopher_michael.pdf Oceanography Doctoral Thesis Doctoral PhD 1994 ftunivcapetownir 2022-09-13T05:48:48Z The western boundary current rings shed from the Agulhas retroflection may be responsible for a considerable transfer of heat, salt and energy from the South Indian into the South Atlantic Ocean. Few hydrographic measurements have been collected from Agulhas rings in the South Atlantic Ocean and their characteristics and influence on the waters of the Cape Basin through which they pass are thus little known. The temperature, salinity, and nutrient data presented in the thesis were collected from three Agulhas rings on a number of recent hydrographic cruises in the South Atlantic Ocean. Temperature profiles, conductivity-temperature-depth measurements, nutrient data, GEOSAT altimeter data, and NOAA-11 satellite imagery were used to investigate one of the rings in May 1989. It had previously been postulated that the rings could have an important effect on the Benguela upwelling system and this thesis demonstrates the interaction of the ring with a filament from the upwelling system. An adverse influence of this interaction on the anchovy larval population is postulated, and cited as a possible cause of the very poor anchovy yearclass of 1989. The other two rings were encountered during winter (August 1990 and June 1992), closer to the retroflection, and only hydrographic observations were possible. One of the rings showed a very deep isothermal surface layer and evidence of a deep pycnostad at its centre. The deep stad is shown to be likely due to vortex stretching and possible sources for the water in the stad are suggested. Comparative hydrographic characteristics, water mass structure, velocity fields, and the potential for contribution to interbasin transfer of the three rings are presented and discussed in the thesis. Doctoral or Postdoctoral Thesis South Atlantic Ocean University of Cape Town: OpenUCT Indian |
institution |
Open Polar |
collection |
University of Cape Town: OpenUCT |
op_collection_id |
ftunivcapetownir |
language |
English |
topic |
Oceanography |
spellingShingle |
Oceanography Duncombe Rae, Christopher Michael Agulhas retroflection rings in the South Atlantic Ocean |
topic_facet |
Oceanography |
description |
The western boundary current rings shed from the Agulhas retroflection may be responsible for a considerable transfer of heat, salt and energy from the South Indian into the South Atlantic Ocean. Few hydrographic measurements have been collected from Agulhas rings in the South Atlantic Ocean and their characteristics and influence on the waters of the Cape Basin through which they pass are thus little known. The temperature, salinity, and nutrient data presented in the thesis were collected from three Agulhas rings on a number of recent hydrographic cruises in the South Atlantic Ocean. Temperature profiles, conductivity-temperature-depth measurements, nutrient data, GEOSAT altimeter data, and NOAA-11 satellite imagery were used to investigate one of the rings in May 1989. It had previously been postulated that the rings could have an important effect on the Benguela upwelling system and this thesis demonstrates the interaction of the ring with a filament from the upwelling system. An adverse influence of this interaction on the anchovy larval population is postulated, and cited as a possible cause of the very poor anchovy yearclass of 1989. The other two rings were encountered during winter (August 1990 and June 1992), closer to the retroflection, and only hydrographic observations were possible. One of the rings showed a very deep isothermal surface layer and evidence of a deep pycnostad at its centre. The deep stad is shown to be likely due to vortex stretching and possible sources for the water in the stad are suggested. Comparative hydrographic characteristics, water mass structure, velocity fields, and the potential for contribution to interbasin transfer of the three rings are presented and discussed in the thesis. |
author2 |
Shillington, Frank A |
format |
Doctoral or Postdoctoral Thesis |
author |
Duncombe Rae, Christopher Michael |
author_facet |
Duncombe Rae, Christopher Michael |
author_sort |
Duncombe Rae, Christopher Michael |
title |
Agulhas retroflection rings in the South Atlantic Ocean |
title_short |
Agulhas retroflection rings in the South Atlantic Ocean |
title_full |
Agulhas retroflection rings in the South Atlantic Ocean |
title_fullStr |
Agulhas retroflection rings in the South Atlantic Ocean |
title_full_unstemmed |
Agulhas retroflection rings in the South Atlantic Ocean |
title_sort |
agulhas retroflection rings in the south atlantic ocean |
publisher |
University of Cape Town |
publishDate |
1994 |
url |
http://hdl.handle.net/11427/18340 https://open.uct.ac.za/bitstream/11427/18340/1/thesis_sci_1994_duncombe_rae_christopher_michael.pdf |
geographic |
Indian |
geographic_facet |
Indian |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_relation |
http://hdl.handle.net/11427/18340 https://open.uct.ac.za/bitstream/11427/18340/1/thesis_sci_1994_duncombe_rae_christopher_michael.pdf |
_version_ |
1766198224791535616 |