Seasonal evolution of physical processes and biological responses in the northern Red Sea

Handle URI:
http://hdl.handle.net/10754/626360
Title:
Seasonal evolution of physical processes and biological responses in the northern Red Sea
Authors:
Asfahani, Khaled ( 0000-0003-0718-4386 )
Abstract:
A sequence of autonomous underwater glider deployments were used to characterize the spatial-temporal variability of the region over an eight month period from late September to May. Strongly stratified system was found in early fall with significant gradients in both temperature (T) and salinity (S), during winter T < 23°C and minimum S of 40.3 psu was observed and resulting in weakened stratification that enables deep convective mixing and upwelling of deep water by cyclonic circulations in the region leading to significant biomass increase. Throughout the entire observational period the slope of the 28 and 28.5 kg/m3 isopycnals remained sloping downward from offshore toward the coast reflected a persistent northward geostrophic flow. The depth of the 180 μmol/kg isopleth of oxygen, indicative of the top of the nutricline, paralleled the depth of the 28 kg/m3, but remained slightly deeper than the isopycnal. The deep winter mixing did not penetrate the nutricline where the mixed layer was deeper near the coast. However, because of the cyclonic signature the 28 kg/m3 rose to the surface offshore, injecting nutrients into the surface layer and promoting increased biomass in the central Red Sea. With the presence of cyclonic eddies, there was evidence of subduction associated with the cross-eddy circulation. This subducted flow was toward the coast within the domain of the glider observations. During this period, increases in the particulate backscatter were associated with increased chlorophyll indicating that the suspended particles were primarily phytoplankton particles. Within the mean northward flow there is a cross-basin flow wherein water is upwelled near the center of the Red Sea, there is a eastward component to the northward flow, and subsequent downwelling near the coasts. Within the surface flow subductive processes lead not only to a horizontal flow, but also a downward component toward the coast. Overall transport is very 3-dimensional in the northern Red Sea, such that northward transport and its associated embedded circulations are northward, while southward transport occurs on the western side of the Red Sea, in contrast to some of the descriptions of flow provided in earlier papers.
Advisors:
Jones, Burton ( 0000-0002-9599-1593 )
Committee Member:
Hoteit, Ibrahim ( 0000-0002-3751-4393 ) ; Berumen, Michael L. ( 0000-0003-2463-2742 ) ; Lee, Craig
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Marine Science
Issue Date:
Dec-2017
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorJones, Burtonen
dc.contributor.authorAsfahani, Khaleden
dc.date.accessioned2017-12-13T09:15:41Z-
dc.date.available2017-12-13T09:15:41Z-
dc.date.issued2017-12-
dc.identifier.urihttp://hdl.handle.net/10754/626360-
dc.description.abstractA sequence of autonomous underwater glider deployments were used to characterize the spatial-temporal variability of the region over an eight month period from late September to May. Strongly stratified system was found in early fall with significant gradients in both temperature (T) and salinity (S), during winter T < 23°C and minimum S of 40.3 psu was observed and resulting in weakened stratification that enables deep convective mixing and upwelling of deep water by cyclonic circulations in the region leading to significant biomass increase. Throughout the entire observational period the slope of the 28 and 28.5 kg/m3 isopycnals remained sloping downward from offshore toward the coast reflected a persistent northward geostrophic flow. The depth of the 180 μmol/kg isopleth of oxygen, indicative of the top of the nutricline, paralleled the depth of the 28 kg/m3, but remained slightly deeper than the isopycnal. The deep winter mixing did not penetrate the nutricline where the mixed layer was deeper near the coast. However, because of the cyclonic signature the 28 kg/m3 rose to the surface offshore, injecting nutrients into the surface layer and promoting increased biomass in the central Red Sea. With the presence of cyclonic eddies, there was evidence of subduction associated with the cross-eddy circulation. This subducted flow was toward the coast within the domain of the glider observations. During this period, increases in the particulate backscatter were associated with increased chlorophyll indicating that the suspended particles were primarily phytoplankton particles. Within the mean northward flow there is a cross-basin flow wherein water is upwelled near the center of the Red Sea, there is a eastward component to the northward flow, and subsequent downwelling near the coasts. Within the surface flow subductive processes lead not only to a horizontal flow, but also a downward component toward the coast. Overall transport is very 3-dimensional in the northern Red Sea, such that northward transport and its associated embedded circulations are northward, while southward transport occurs on the western side of the Red Sea, in contrast to some of the descriptions of flow provided in earlier papers.en
dc.language.isoenen
dc.subjectNorthern Red Seaen
dc.subjectWater formationen
dc.subjectWinter circulationen
dc.subjectdeep convictionen
dc.subjectphytoplankton biomassen
dc.subjectcyclonic eddiesen
dc.titleSeasonal evolution of physical processes and biological responses in the northern Red Seaen
dc.typeDissertationen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen
dc.contributor.committeememberHoteit, Ibrahimen
dc.contributor.committeememberBerumen, Michael L.en
dc.contributor.committeememberLee, Craigen
thesis.degree.disciplineMarine Scienceen
thesis.degree.nameDoctor of Philosophyen
dc.person.id125242en
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