High Resolution Circulation of the Hawkesbury Shelf Region, SE Australia: Mean, Variability and Transport Pathways

dc.contributor.advisor Roughan, Moninya en_US
dc.contributor.advisor Suthers, Iain en_US Ribbat, Nina en_US 2022-03-23T12:16:53Z 2022-03-23T12:16:53Z 2020 en_US
dc.description.abstract The exchange between the open ocean and coastal waters within continental shelf systems is driven by complex circulation processes making it hard to measure and observe. They are highly productive regions, sustaining marine ecosystems and are often nursery areas for many organisms, providing the basis for a variety of natural resources of high economic importance. Along southeastern Australia, the shelf circulation has been studied through in situ temperature and velocity observations, coarse resolution satellite data and modelling studies. However, due to the lack of high spatial resolution data over continued time periods, the circulation over the shelf as a system has not yet been explored. The general aims of this thesis are to assess the mean and time varying circulation over the Hawkesbury Shelf (HS, 31.5-34.5oS) to understand the influence of the EAC on the shelf circulation variability; and to identify water sources of an offshore artificial reef off Sydney. Towards these aims, a high-resolution version of the Regional Ocean Modelling System (ROMS) is configured to model the circulation on the HS for 2012 and 2013. Robust model validation against high-resolution observations shows that the model achieves a reliable representation of the circulation on the shelf. Mean along and across-shelf transports are quantified to identify major regions of ocean/shelf exchange and its spatial and temporal variability. Throughout the year, maximum shelf-water export is associated with the eastward separation of the EAC jet between 31 and 32.5oS. Downstream of the EAC separation, transports become more variable and weaker in magnitude. While the EAC separation creates distinct circulation regimes outside the 200 m isobath, the inner shelf remains unaffected by the EAC variability as indicated by high correlations of along-shelf transports along the coast. Finally, the model is used to understand the movement of water over the inner shelf, with particular focus on the source of water arriving at an offshore artificial reef (OAR) off Sydney. Using Lagrangian particle tracking, the source of water reaching the continental shelf is identified to discern regions that are more likely to be productive. Backward water parcel trajectories reveal that deep offshore waters come mainly from middle shelf regions between 33 and 33.5oS and also from the south, downstream of the typical EAC separation latitudes. In contrast, waters found in inner shelf regions come from the north by poleward flowing inshore waters. The results suggest that seasonal variability in source water location is low; however, the region where the source waters come from is narrow in summer and broader in autumn and winter. Results presented in this thesis aid in understanding the influence of mesoscale variability on the coastal circulation and transport of waters to the inner shelf. en_US
dc.language English
dc.language.iso EN en_US
dc.publisher UNSW, Sydney en_US
dc.rights CC BY-NC-ND 3.0 en_US
dc.rights.uri en_US
dc.subject.other Artificial Reef en_US
dc.subject.other EAC en_US
dc.subject.other Shelf Transport en_US
dc.title High Resolution Circulation of the Hawkesbury Shelf Region, SE Australia: Mean, Variability and Transport Pathways en_US
dc.type Thesis en_US
dcterms.accessRights open access
dcterms.rightsHolder Ribbat, Nina
dspace.entity.type Publication en_US
unsw.isDatasetRelatedToPublication A high-resolution, 26-year, free-running, hydrodynamic simulation of the East Australia Current System using the Regional Ocean Modeling System (Version 3.0)
unsw.relation.faculty Science
unsw.relation.originalPublicationAffiliation Ribbat, Nina, Mathematics & Statistics, Faculty of Science, UNSW en_US
unsw.relation.originalPublicationAffiliation Roughan, Moninya, Mathematics & Statistics, Faculty of Science, UNSW en_US
unsw.relation.originalPublicationAffiliation Suthers, Iain, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW en_US School of Mathematics & Statistics *
unsw.thesis.degreetype PhD Doctorate en_US
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