A fine-scale volumetric census of the water masses of the Agulhas retroflection area

Simple item page
dc.contributor.advisorBrundrit, Geoff Ben_ZA
dc.contributor.authorValentine, Henry Richarden_ZA
dc.date.accessioned2016-10-16T09:52:30Z
dc.date.available2016-10-16T09:52:30Z
dc.date.issued1990en_ZA
dc.description.abstractTwo studies of the quantification of water masses around southern Africa are described in this thesis. The first, a pilot study, is concerned with the volumetric analysis of historic hydrographic data from the region off the South African west coast. It uses data that have been collected with various instruments over a considerable period of time and with relatively poor vertical and horizontal resolution. Nevertheless meaningful and significant results have been obtained: (i) The T/S characteristics of the upwelling domain and the open-ocean are significantly different and show no overlap. Upwelled water is derived from different parts of the South Atlantic Central Water mass. (ii) Upwelled water, irrespective of its particular origin the Central Water mass, eventually is heated to a limit of 23°C. (iii) The volume of water in each bivariate T/S class of Central Water, which is available for upwelling, are constant. This implies that the intensity of upwelling may be estimated from the salinity of the upwelled water only. The second or main study is concerned with the Agulhas Retroflection area. This is located in the broader South-East Atlantic/South West Indian ocean region, which is identified as a serious gap in a previously published fine-scale volumetric census of the world ocean. Recently collected, high quality hydrographic data make it possible to rectify this. This is the principle objective of this thesis. Some results include: I. The subtle differences between the Central water of South Atlantic Ocean origin and that of the South Indian ocean were addressed. These differences are real and distinguishable as is shown using both historic data and high quality hydrographic data. 2. For the first time, reliable quantitative estimates for the warm and thermocline water masses are produced. The warm, saline surface water of the Agulhas Retroflection area contributes very little to the overall volume of the upper 1500 m of the water column. 3. The low salinity water from south of the Subtropical Convergence is spread widely (in T/S space) on the less saline side of the three-dimensional volumetric diagrams and has very little volume (less than 1% of the total volume). 4. The more saline, higher volume section of the Central Water in this region corresponds to South West Indian Central Water. 5. Twenty five percent of the total volume of water in this region is contained in only 21 fine-scale bivariate classes. 6. Fifty percent of the water (contained in 71 classes) has a temperature below 3°C. If the lower volume. non-ranked classes were added then almost seventy percent (67,26%) of all the water in the Retroflection area would be colder than 3°C. The results of this census are compared with those of the world ocean census. Although the volume per bivariate class interval is not of the same order of magnitude, the results are remarkably similar. The water masses of the Retroflection area are less diverse than those of the world ocean.en_ZA
dc.identifier.apacitationValentine, H. R. (1990). <i>A fine-scale volumetric census of the water masses of the Agulhas retroflection area</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Oceanography. Retrieved from http://hdl.handle.net/11427/22162en_ZA
dc.identifier.chicagocitationValentine, Henry Richard. <i>"A fine-scale volumetric census of the water masses of the Agulhas retroflection area."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Oceanography, 1990. http://hdl.handle.net/11427/22162en_ZA
dc.identifier.citationValentine, H. 1990. A fine-scale volumetric census of the water masses of the Agulhas retroflection area. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Valentine, Henry Richard AB - Two studies of the quantification of water masses around southern Africa are described in this thesis. The first, a pilot study, is concerned with the volumetric analysis of historic hydrographic data from the region off the South African west coast. It uses data that have been collected with various instruments over a considerable period of time and with relatively poor vertical and horizontal resolution. Nevertheless meaningful and significant results have been obtained: (i) The T/S characteristics of the upwelling domain and the open-ocean are significantly different and show no overlap. Upwelled water is derived from different parts of the South Atlantic Central Water mass. (ii) Upwelled water, irrespective of its particular origin the Central Water mass, eventually is heated to a limit of 23°C. (iii) The volume of water in each bivariate T/S class of Central Water, which is available for upwelling, are constant. This implies that the intensity of upwelling may be estimated from the salinity of the upwelled water only. The second or main study is concerned with the Agulhas Retroflection area. This is located in the broader South-East Atlantic/South West Indian ocean region, which is identified as a serious gap in a previously published fine-scale volumetric census of the world ocean. Recently collected, high quality hydrographic data make it possible to rectify this. This is the principle objective of this thesis. Some results include: I. The subtle differences between the Central water of South Atlantic Ocean origin and that of the South Indian ocean were addressed. These differences are real and distinguishable as is shown using both historic data and high quality hydrographic data. 2. For the first time, reliable quantitative estimates for the warm and thermocline water masses are produced. The warm, saline surface water of the Agulhas Retroflection area contributes very little to the overall volume of the upper 1500 m of the water column. 3. The low salinity water from south of the Subtropical Convergence is spread widely (in T/S space) on the less saline side of the three-dimensional volumetric diagrams and has very little volume (less than 1% of the total volume). 4. The more saline, higher volume section of the Central Water in this region corresponds to South West Indian Central Water. 5. Twenty five percent of the total volume of water in this region is contained in only 21 fine-scale bivariate classes. 6. Fifty percent of the water (contained in 71 classes) has a temperature below 3°C. If the lower volume. non-ranked classes were added then almost seventy percent (67,26%) of all the water in the Retroflection area would be colder than 3°C. The results of this census are compared with those of the world ocean census. Although the volume per bivariate class interval is not of the same order of magnitude, the results are remarkably similar. The water masses of the Retroflection area are less diverse than those of the world ocean. DA - 1990 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1990 T1 - A fine-scale volumetric census of the water masses of the Agulhas retroflection area TI - A fine-scale volumetric census of the water masses of the Agulhas retroflection area UR - http://hdl.handle.net/11427/22162 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/22162
dc.identifier.vancouvercitationValentine HR. A fine-scale volumetric census of the water masses of the Agulhas retroflection area. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Oceanography, 1990 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/22162en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Oceanographyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherOceanographyen_ZA
dc.titleA fine-scale volumetric census of the water masses of the Agulhas retroflection areaen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
thesis_sci_1990_valentine_henry_richard.pdf
Size:
3.97 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Masters