{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/42589"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/42589","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Evaluating multi-satellite chlorophyll-a datasets an ocean colour case study within the Southern Benguela","abstract":"Chlorophyll-a (chl-a), a photosynthetic pigment that can be derived from satellite ocean colour, is often used as a proxy for phytoplankton biomass and to derive primary productivity. Initiatives such as the Ocean Colour Climate Change Initiative (OC-CCI) produce merged multi-satellite products to create consistent long-term time-series datasets for climate studies at a global scale. Their ability to handle variable in-water conditions is critical for their mission parameters. This study compares the performance of two European multi-satellite chl-a products, from the OC-CCI and GlobColour projects against a regionally tuned Sentinel-3 product within the Southern Benguela region. The three products were assessed against a collated database of coincident in situ chl-a matchups to derive a series of performance metrics. The regionally tuned Sentinel-3 product outperformed the two global products in terms of Mean Absolute Error but showed a slight consistent overestimation bias. Analysis of match-ups showed an underestimation of high chl-a concentrations and overestimation of lower chl-a concentrations by both global products. An application of the products within St.Helena bay during high biomass bloom events showed that the Sentinel-3 product's ability to capture extreme chl-a concentrations was far higher than both global products. Spatial mismatch between zones of high chl-a concentration also indicate differences in processing chains and flagging techniques.","abstract_html":"Chlorophyll-a (chl-a), a photosynthetic pigment that can be derived from satellite ocean colour, is often used as a proxy for phytoplankton biomass and to derive primary productivity. Initiatives such as the Ocean Colour Climate Change Initiative (OC-CCI) produce merged multi-satellite products to create consistent long-term time-series datasets for climate studies at a global scale. Their ability to handle variable in-water conditions is critical for their mission parameters. This study compares the performance of two European multi-satellite chl-a products, from the OC-CCI and GlobColour projects against a regionally tuned Sentinel-3 product within the Southern Benguela region. The three products were assessed against a collated database of coincident in situ chl-a matchups to derive a series of performance metrics. The regionally tuned Sentinel-3 product outperformed the two global products in terms of Mean Absolute Error but showed a slight consistent overestimation bias. Analysis of match-ups showed an underestimation of high chl-a concentrations and overestimation of lower chl-a concentrations by both global products. An application of the products within St.Helena bay during high biomass bloom events showed that the Sentinel-3 product's ability to capture extreme chl-a concentrations was far higher than both global products. Spatial mismatch between zones of high chl-a concentration also indicate differences in processing chains and flagging techniques.","abstract_has_math":false,"creators":["Oehley, Craig"],"institution":"Department of Biological Sciences","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["CSIR, Smith","CSIR, Whittle"],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025","date_published":"2025","updated_at":"2026-07-22T22:23:31Z","subjects":["Ocean colour","Southern Benguela"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/42589","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["CSIR, Smith","CSIR, Whittle"]},{"key":"dc:creator","label":"Author","values":["Oehley, Craig"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-01-16T10:02:19Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-01-16T10:02:19Z"]},{"key":"dc:date.issued","label":"Date","values":["2025"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Biological Sciences"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Thesis / Dissertation"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters","MSc"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Ocean colour","Southern Benguela"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/42589"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Chlorophyll-a (chl-a), a photosynthetic pigment that can be derived from satellite ocean colour, is often used as a proxy for phytoplankton biomass and to derive primary productivity. Initiatives such as the Ocean Colour Climate Change Initiative (OC-CCI) produce merged multi-satellite products to create consistent long-term time-series datasets for climate studies at a global scale. Their ability to handle variable in-water conditions is critical for their mission parameters. This study compares the performance of two European multi-satellite chl-a products, from the OC-CCI and GlobColour projects against a regionally tuned Sentinel-3 product within the Southern Benguela region. The three products were assessed against a collated database of coincident in situ chl-a matchups to derive a series of performance metrics. The regionally tuned Sentinel-3 product outperformed the two global products in terms of Mean Absolute Error but showed a slight consistent overestimation bias. Analysis of match-ups showed an underestimation of high chl-a concentrations and overestimation of lower chl-a concentrations by both global products. An application of the products within St.Helena bay during high biomass bloom events showed that the Sentinel-3 product's ability to capture extreme chl-a concentrations was far higher than both global products. Spatial mismatch between zones of high chl-a concentration also indicate differences in processing chains and flagging techniques."]},{"key":"dc:title","label":"Title","values":["Evaluating multi-satellite chlorophyll-a datasets an ocean colour case study within the Southern Benguela"]}]}],"canonical_facts":{"dc:contributor.advisor":["CSIR, Smith","CSIR, Whittle"],"dc:creator":["Oehley, Craig"],"dc:date.accessioned":["2026-01-16T10:02:19Z"],"dc:date.available":["2026-01-16T10:02:19Z"],"dc:date.issued":["2025"],"dc:description.abstract":["Chlorophyll-a (chl-a), a photosynthetic pigment that can be derived from satellite ocean colour, is often used as a proxy for phytoplankton biomass and to derive primary productivity. Initiatives such as the Ocean Colour Climate Change Initiative (OC-CCI) produce merged multi-satellite products to create consistent long-term time-series datasets for climate studies at a global scale. Their ability to handle variable in-water conditions is critical for their mission parameters. This study compares the performance of two European multi-satellite chl-a products, from the OC-CCI and GlobColour projects against a regionally tuned Sentinel-3 product within the Southern Benguela region. The three products were assessed against a collated database of coincident in situ chl-a matchups to derive a series of performance metrics. The regionally tuned Sentinel-3 product outperformed the two global products in terms of Mean Absolute Error but showed a slight consistent overestimation bias. Analysis of match-ups showed an underestimation of high chl-a concentrations and overestimation of lower chl-a concentrations by both global products. An application of the products within St.Helena bay during high biomass bloom events showed that the Sentinel-3 product's ability to capture extreme chl-a concentrations was far higher than both global products. Spatial mismatch between zones of high chl-a concentration also indicate differences in processing chains and flagging techniques."],"dc:identifier.uri":["http://hdl.handle.net/11427/42589"],"dc:language.iso":["en"],"dc:publisher.department":["Department of Biological Sciences"],"dc:publisher.institution":["University of Cape Town"],"dc:subject":["Ocean colour","Southern Benguela"],"dc:title":["Evaluating multi-satellite chlorophyll-a datasets an ocean colour case study within the Southern Benguela"],"dc:type":["Thesis / Dissertation"],"dc:type.qualificationlevel":["Masters","MSc"]},"updated_at":"2026-07-22T22:23:31Z"}