ORCID Profile
0000-0003-3825-7533
Current Organisation
UNSW Australia
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Oceanography | Physical Oceanography | Marine and Estuarine Ecology (incl. Marine Ichthyology) | Oceanography | Biological Oceanography | Physical oceanography | Ecological Impacts of Climate Change | Photogrammetry and remote sensing | Wildlife and Habitat Management | Ecology | Ecological Applications | Maritime Engineering not elsewhere classified | Biological Oceanography | Chemical Oceanography | Physical Oceanography | Biological oceanography | Chemical oceanography | Ecosystem Function | Computational Fluid Dynamics | Fisheries Management |
ANZSRC Socio-Economic Objective (SEO)
Marine Oceanic Processes (excl. climate related) | Climate Variability (excl. Social Impacts) | Ecosystem Assessment and Management of Marine Environments | Ecosystem Adaptation to Climate Change | Ecosystem Assessment and Management of Coastal and Estuarine Environments | Coastal and Marine Management Policy | Fisheries - Recreational | Climate change | Integrated (ecosystem) assessment and management | Oceanic processes (excl. climate related) | Marine Flora, Fauna and Biodiversity
Related Links
Publications
A numerical modeling study of the East Australian Current encircling and overwashing a warm‐core eddy
Publisher: American Geophysical Union (AGU)
Date: 2013
DOI: 10.1029/2012JC008386
Shelf Transport Pathways Adjacent to the East Australian Current Reveal Sources of Productivity for Coastal Reefs
Publisher: Frontiers Media SA
Date: 07-01-2022
DOI: 10.3389/FMARS.2021.789687
Abstract: The region where the East Australian Current (EAC) separates from the coast is dynamic and the shelf circulation is impacted by the interplay of the western boundary current and its eddy field with the coastal ocean. This interaction can drive upwelling, retention or export. Hence understanding the connection between offshore waters and the inner shelf is needed as it influences the productivity potential of valuable coastal rocky reefs. Near urban centres, artificial reefs enhance fishing opportunities in coastal waters, however these reefs are located without consideration of the productivity potential of adjacent waters. Here we identify three dominant modes of mesoscale circulation in the EAC separation region (~31.5−34.5°S) the ‘EAC mode’ which dominates the flow in the poleward direction, and two eddy modes, the ‘EAC eddy mode’ and the ‘Eddy dipole mode’, which are determined by the configuration of a cyclonic and anticyclonic eddy and the relationship with the separated EAC jet. We use a Lagrangian approach to reveal the transport pathways across the shelf to understand the impact of the mesoscale circulation modes and to explore the productivity potential of the coastal waters. We investigate the origin (position and depth) of the water that arrives at the inner-mid shelf over a 21-day period (the plankton productivity timescale). We show that the proportion of water that is upwelled from below the euphotic zone varies spatially, and with each mesoscale circulation mode. Additionally, shelf transport timescales and pathways are also impacted by the mesoscale circulation. The highest proportion of upwelling (70%) occurs upstream of 32.5°S, associated with the EAC jet separation, with vertical displacements of 70–120 m. From 33 to 33.5°S, water comes from offshore above the euphotic layer, and shelf transport timescales are longest. The region of highest retention over the inner shelf is immediately downstream of the EAC separation region. The position of the EAC jet and the location of the cyclonic eddy determines the variability in shelf-ocean interactions and the productivity of shelf waters. These results are useful for understanding productivity of temperate rocky reefs in general and specifically for fisheries enhancements along an increasingly urbanised coast.
The Effect of Ionizing Gamma Radiation on Natural and Synthetic Fibers and Its Implications for the Forensic Examination of Fiber Evidence*
Publisher: Wiley
Date: 09-02-2011
DOI: 10.1111/J.1556-4029.2010.01654.X
Abstract: Circumstances of criminal activities involving radioactive materials may mean fiber evidence recovered from a crime scene could have been exposed to materials emitting ionizing radiation. The consequences of radiation exposed fibers on the result of the forensic analysis and interpretation is explored. The effect of exposure to 1-1000 kGy radiation doses in natural and synthetic fibers was noticeable using comparative forensic examination methods, such as optical microscopy, microspectrophotometry, and thin-layer chromatography. Fourier transform infrared spectroscopy analysis showed no signs of radiation-induced chemical changes in any of the fiber structures. The outcome of the comparative methods highlights the risk of "false negatives" associated in comparing colors of recovered fibers that may have been exposed to unknown radiation doses. Consideration of such results supports the requirement to know the context, including the environmental conditions, as much as possible before undertaking a forensic fiber examination.
Lagrangian and Eulerian characterization of two counter‐rotating submesoscale eddies in a western boundary current
Publisher: American Geophysical Union (AGU)
Date: 06-2017
DOI: 10.1002/2016JC011968
Environmental correlates of relative abundance of potentially dangerous sharks in nearshore areas, southeastern Australia
Publisher: Inter-Research Science Center
Date: 12-07-2018
DOI: 10.3354/MEPS12611
Downstream Evolution of the East Australian Current System: Mean Flow, Seasonal, and Intra‐annual Variability
Publisher: American Geophysical Union (AGU)
Date: 27-04-2020
DOI: 10.1029/2019JC015227
Abstract: The East Australian Current (EAC) varies on both seasonal and mesoscale eddy related timescales, with important impacts for weather, primary productivity, and fisheries. While the EAC and its eddies have been the subject of many synoptic studies, a consistent three‐dimensional picture of the current, its downstream evolution, and the associated seasonal and intra‐annual variability is lacking. We use a 22‐year model simulation to quantify the EAC's temporal and latitudinal variability, from where it flows as a mostly coherent jet (27° S) to its separation from the coast (31–33° S), its energetic eddy field in the Tasman Sea and its southern extension. We show that the current intensifies and deepens poleward toward the separation latitude the mean poleward transport reaches a maximum of 26.8 Sv and the seasonal cycle litude peaks at 6.2 Sv. Over the separation region, the EAC core broadens and shallows, mean poleward transport is lower and the transport standard deviation peaks at 22.0 Sv. The meandering EAC jet is modulated at interannual timescales, while the eddy driven transport over the separation region has a strong annual modulation, related to the annual cycle in eddy kinetic energy. SSH variability at intra‐annual frequencies is described primarily by an alongshore propagating mode and an onshore propagating mode, demonstrating that mesoscale SSH variability stems from a combination of intrinsic instabilities of the EAC jet and westward propagating Rossby waves. The results provide the first holistic analysis of the EAC system along its latitudinal range.
Building multidisciplinary collaboration in coastal and ocean modelling and observation in Australasia
Publisher: Elsevier BV
Date: 06-2020
Transport variability over the Hawkesbury Shelf (31.5–34.5°S) driven by the East Australian Current
Publisher: Public Library of Science (PLoS)
Date: 05-11-2020
DOI: 10.1371/JOURNAL.PONE.0241622
Abstract: The Hawkesbury Bioregion located off southeastern Australia (31.5–34.5 o S) is a region of highly variable circulation. The region spans the typical separation point of the East Australian Current (EAC), the western boundary current that dominates the flow along the coast of SE Australia. It lies adjacent to a known ocean warming hotspot in the Tasman Sea, and is a region of high productivity. However, we have limited understanding of the circulation, temperature regimes and shelf transport in this region, and the drivers of variability. We configure a high resolution (750m) numerical model for the Hawkesbury Shelf region nested inside 2 data assimilating models of decreasing resolution, to obtain the best estimate of the shelf circulation and transport over a 2-yr period (2012–2013). Here we show that the transport is driven by the mesoscale EAC circulation that strengthens in summer and is related to the separation of the EAC jet from the coast. Transport estimates show strong offshore export is a maximum between 32-33 o S. Median offshore transports range 2.5–8.4Sv seasonally and are a maximum during in summer driven by the separation of the EAC jet from the coast. The transport is more variable downstream of the EAC separation, driven by the EAC eddy field. Onshore transport occurs more frequently off Sydney 33.5–34.5 o S seasonal medians range -1.7 to 2.3Sv, with an onshore maximum in winter. The region is biologically productive, and it is a known white shark nursery area despite the dominance of the oligotrophic western boundary current. Hence an understanding of the drivers of circulation and cross-shelf exchange is important.
Variation in the strength of continental boundary currents determines continent-wide connectivity in kelp
Publisher: Wiley
Date: 17-03-2011
The strengthening East Australian Current, its eddies and biological effects - an introduction and overview
Publisher: Elsevier BV
Date: 03-2011
Drivers of ocean warming in the western boundary currents of the Southern Hemisphere
Publisher: Springer Science and Business Media LLC
Date: 29-09-2022
The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts
Publisher: The Royal Society
Date: 22-08-2014
Abstract: Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to ‘barrens’ when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs.
Subsurface recirculation and larval retention in the lee of a small headland: A variation on the upwelling shadow theme
Publisher: American Geophysical Union (AGU)
Date: 10-2005
DOI: 10.1029/2005JC002898
Observations of Submesoscale Variability and Frontal Subduction within the Mesoscale Eddy Field of the Tasman Sea
Publisher: American Meteorological Society
Date: 05-2020
Abstract: Submesoscale lenses of water with anomalous hydrographic properties have previously been observed in the East Australian Current (EAC) system, embedded within the thermocline of mesoscale anticyclonic eddies. The waters within these lenses have high oxygen content and temperature–salinity properties that signify a surface origin. However, it is not known how these lenses form. This study presents field observations that provide insight into a possible generation mechanism via subduction at upper-ocean fronts. High-resolution hydrographic and velocity measurements of submesoscale activity were taken across a front between a mesoscale eddy dipole downstream of the EAC separation point. The front had O (1) Rossby number, strong vertical shear, and flow conducive to symmetric instability. Frontogenesis was measured in conjunction with subduction of an anticyclonic water parcel, indicative of intrathermocline eddy formation. Twenty-five years of satellite imagery reveals the existence of strong mesoscale strain coupled with strong temperature fronts in this region and indicates the conditions that led to frontal subduction observed here are a persistent feature. These processes impact the vertical export of tracers from the surface and dissipation of mesoscale kinetic energy, implicating their importance for understanding regional ocean circulation and biological productivity.
A National Reference Station infrastructure for Australia using telemetry and central processing to report multi-disciplinary data streams for monitoring marine ecosystem response to climate change
Publisher: IEEE
Date: 2008
On the Variability of the East Australian Current: Jet Structure, Meandering, and Influence on Shelf Circulation
Publisher: American Geophysical Union (AGU)
Date: 11-2017
DOI: 10.1002/2017JC013097
Corrigendum to Cross-shelf dynamics in a western boundary current regime: Implications for upwelling [J. Phys. Oceanogr., 43, (2013) 1042-1059] DOI: 10.1175/JPO-D-12-0177.1
Publisher: American Meteorological Society
Date: 10-2014
Mesoscale oceanographic features drive divergent patterns in connectivity for co‐occurring estuarine portunid crabs
Publisher: Wiley
Date: 07-09-2022
DOI: 10.1111/FOG.12608
Abstract: Larval dispersal and connectivity have important implications for fisheries management, especially for species with life cycles influenced by ocean boundary currents. Giant Mud Crab ( Scylla serrata ) and Blue Swimmer Crab ( Portunus armatus ) are two estuarine portunid crabs (Family: Portunidae) that support significant commercial and recreational harvest in eastern Australia. Giant Mud Crab migrate to coastal waters to spawn, and while Blue Swimmer Crab spawn primarily within estuaries they occasionally migrate to coastal waters to spawn, followed by larval dispersal in the East Australian Current (EAC). Here, we coupled a high‐resolution oceanographic model with a Lagrangian particle tracking framework to simulate larval dispersal and determine the extent of population connectivity in this region. Our simulations indicate broad‐scale connectivity (~40–400 km), characterised by high inter‐estuary connectivity. Overall, our results suggest a north‐to‐south source‐sink structure for both species, with contributions of particles from the north ranging from 51% to 99%. Recruitment to a given estuary is dependent on the proximity of mesoscale oceanographic features of the EAC. Most notably, the EAC separation acts as a barrier to recruitment between spawning and settlement to the north/south of this region. This significantly limits interjurisdictional connectivity for these species, especially Blue Swimmer Crab, likely due to a shorter pelagic larval duration than Giant Mud Crab. Our results provide evidence to inform the assessment and management of these species.
Sydney Harbour: What we do and do not know about a highly diverse estuary
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF15159
Abstract: Sydney Harbour is a global hotspot for marine and estuarine ersity. Despite its social, economic and biological value, the available knowledge has not previously been reviewed or synthesised. We systematically reviewed the published literature and consulted experts to establish our current understanding of the Harbour’s natural systems, identify knowledge gaps, and compare Sydney Harbour to other major estuaries worldwide. Of the 110 studies in our review, 81 focussed on ecology or biology, six on the chemistry, 10 on geology and 11 on oceanography. Subtidal rocky reef habitats were the most studied, with a focus on habitat forming macroalgae. In total 586 fish species have been recorded from the Harbour, which is high relative to other major estuaries worldwide. There has been a lack of process studies, and an almost complete absence of substantial time series that constrains our capacity to identify trends, environmental thresholds or major drivers of biotic interactions. We also highlight a lack of knowledge on the ecological functioning of Sydney Harbour, including studies on microbial communities. A sound understanding of the complexity, connectivity and dynamics underlying ecosystem functioning will allow further advances in management for the Harbour and for similarly modified estuaries around the world.
Eddy‐Driven Cross‐Shelf Transport in the East Australian Current Separation Zone
Publisher: American Geophysical Union (AGU)
Date: 02-2020
DOI: 10.1029/2019JC015613
Abstract: In western boundary current systems, sharp velocity gradients between the poleward flowing jet and coastal waters generally act to inhibit cross‐shelf exchange. Downstream of jet separation, dynamic mesoscale eddies dominate the flow. In the East Australian Current System, counter‐rotating eddy dipoles are often present which, in the appropriate configuration, have potential to drive cross‐shelf transport. However, this eddy dipole mode is poorly understood in the framework of cross‐shelf exchange and the effect of these structures on shelf waters is uncertain. Using 25 years of satellite altimetry, as well as in situ s ling of a typical dipole event, we investigate the characteristics of eddy‐driven cross‐shelf exchange. We show that the maximum onshore velocity is driven by an eddy dipole structure and occurs in a defined latitudinal band between 33°S and 34°S more than 50% of the time. We s le a typical eddy dipole and find a strong onshore jet, 37 km wide, with velocities up to 1.78 m s and a transport of at least 16 Sv. Hydrographic data from an autonomous underwater glider show that this jet manifests on the shelf as a subsurface intrusion of warm salty water extending from offshore up onto the midshelf. In the light of climatic changes in western boundary current transport and the increase in their eddy kinetic energy, understanding eddy‐driven cross‐shelf exchange is important to predict future changes to the shelf water mass.
Comparison of the cross-shelf phytoplankton distribution of two oceanographically distinct regions off Australia
Publisher: Elsevier BV
Date: 08-2015
Multi-decadal ocean temperature time-series and climatologies from Australia’s long-term National Reference Stations
Publisher: Springer Science and Business Media LLC
Date: 07-04-2022
DOI: 10.1038/S41597-022-01224-6
Abstract: Multi-decadal ocean time-series are fundamental baselines for assessing the impacts of environmental change, however, compiling and quality controlling historic data from multiple sources remains challenging. Here we aggregate, document, and release a number of long time-series temperature products and climatologies compiled from data obtained at 4 monitoring sites around Australia where sub-surface ocean temperature has been recorded nominally weekly to monthly since the 1940s/50s. In recent years, the s ling was augmented with data obtained from moored sensors, vertical profiles and satellite-derived data. The temperature data have been quality controlled, and combined using a rigorously tested methodology. We have packaged the multi-decadal, multi-depth, multi-platform temperature time-series at each site and produced a range of daily temperature climatologies from different data combinations and time periods. The 17 data products are provided as CF-compliant NetCDF files and will be updated periodically. The long-term temperature time-series will be useful for studies of ocean temperature variability, trends, anomalies and change. The data collection is supported by Australia’s Integrated Marine Observing System and data are open-access.
Marine heatwaves in shallow coastal ecosystems are coupled with the atmosphere: Insights from half a century of daily in situ temperature records
Publisher: Frontiers Media SA
Date: 03-11-2022
DOI: 10.3389/FCLIM.2022.1012022
Abstract: Marine heatwaves (MHWs) are extreme ocean temperature events that can have wide-ranging and pervasive effects on marine species and ecosystems. However, studies of MHW characteristics and drivers primarily focus on open-ocean environments, rather than the nearshore coastal ocean (& km from coast, & m depth). This is despite coastal waters sustaining significant commercial, recreational, and customary fisheries and aquaculture activities that are highly susceptible to the impacts of MHWs. The two longest (& year) daily in situ ocean temperature records in the Southern Hemisphere are used to investigate the variability, drivers, and trends of MHWs in shallow water marine ecosystems (SWMEs). Located at the northern and southern limits of New Zealand, both locations experience an average of two to three MHWs annually, with MHWs at the exposed coastline site generally being of longer duration but less intense than those observed within the semi-enclosed harbor site. Observed MHWs have timescales similar to synoptic weather systems (9–13 days) and are most intense during Austral summer with little seasonality in frequency or duration. An investigation of MHWs co-occurring in nearshore coastal and offshore waters suggests that MHWs in semi-enclosed waters (e.g., harbors, estuaries) are more closely coupled with local atmospheric conditions and less likely to have a co-occurring offshore MHW than those occurring on exposed coastlines. Composite analysis using a reanalysis product elucidates specific atmospheric drivers and suggests that atmospheric pressure systems, wind speed and latent heat fluxes are important contributing factors to the generation and decline of MHWs in SWMEs. Investigation of long-term trends in MHW properties revealed an increase in MHW duration and annual MHW days at the southern site and decrease in maximum intensity at the northern site. This is consistent with broad-scale warming trends previously documented at these coastal stations, with differences related to changes in large-scale circulation patterns around New Zealand. Our results highlight the importance of in situ data for the analysis of MHW events in the nearshore coastal ocean, and the role of local atmospheric forcing in modulating the occurrence of MHWs in SWMEs, which can cause decoupling of temperature dynamics with the surrounding shelf sea.
Assessment of Surface Currents Measured With High-Frequency Phased-Array Radars in Two Regions of Complex Circulation
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2017
The Kinematic Similarity of Two Western Boundary Currents Revealed by Sustained High‐Resolution Observations
Publisher: American Geophysical Union (AGU)
Date: 25-06-2018
DOI: 10.1029/2018GL078429
Revisiting the circulation of the East Australian Current: Its path, separation, and eddy field
Publisher: Elsevier BV
Date: 09-2019
Mass-transfer-limited nitrate uptake on a coral reef flat, Warraber Island, Torres Strait, Australia
Publisher: Springer Science and Business Media LLC
Date: 28-07-2004
Influence of a western boundary current on shelf dynamics and upwelling from repeat glider deployments
Publisher: American Geophysical Union (AGU)
Date: 13-01-2015
DOI: 10.1002/2014GL062260
Energetics of Eddy–Mean Flow Interactions in the East Australian Current System
Publisher: American Meteorological Society
Date: 02-2023
Abstract: Examining eddy–mean flow interactions in western boundary currents is crucial for understanding the mechanisms of mesoscale eddy generation and the role of eddies in the large-scale circulation. However, this analysis is lacking in the East Australian Current (EAC) system. Here we show the detailed three-dimensional structure of the eddy–mean flow interactions and energy budget in the EAC system. The energy reservoirs and conversions are greatest in the upper 500 m, with complex vertical structures. Strong mean kinetic energy is confined within a narrow band (24.5°–32.5°S) in the EAC jet. Most energy is contained in the eddy fields instead of the mean flow in the EAC typical separation and extension regions (south of 32.5°S). Strong barotropic instability is the primary source of eddy kinetic energy north of 36°S, while baroclinic instability dominates the eddy kinetic energy production in the EAC southern extension, which peaks in the subsurface. The mean flow transfers 5.22 GW of kinetic energy and 3.33 GW of available potential energy to the eddy field in the EAC typical separation region. The largest conversion term is from available potential energy conversion from the mean flow to the eddy field through baroclinic instability, dominating between 29° and 35.5°S. Nonlocal eddy–mean flow interactions also play a role in the energy exchange between the mean flow and the eddy fields. This study provides the mean state of the eddy–mean flow interactions in the EAC system, paving the way for further studies exploring seasonal and interannual variability and provides a baseline for assessing the impact of environmental change.
Sydney Harbour: A review of anthropogenic impacts on the biodiversity and ecosystem function of one of the world's largest natural harbours
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF15157
Abstract: Sydney Harbour is a hotspot for ersity. However, as with estuaries worldwide, its ersity and functioning faces increasing threats from urbanisation. This is the first synthesis of threats and impacts in Sydney Harbour. In total 200 studies were reviewed: 109 focussed on contamination, 58 on habitat modification, 11 addressed non-indigenous species (NIS) and eight investigated fisheries. Metal concentrations in sediments and seaweeds are among the highest recorded worldwide and organic contamination can also be high. Contamination is associated with increased abundances of opportunistic species, and changes in benthic community structure. The Harbour is also heavily invaded, but invaders’ ecological and economic impacts are poorly quantified. Communities within Sydney Harbour are significantly affected by extensive physical modification, with artificial structures supporting more NIS and lower ersity than their natural equivalents. We know little about the effects of fishing on the Harbour’s ecology, and although ocean warming along Sydney is among the fastest in the world, we know little about how the ecosystem will respond to warming. The interactive and cumulative effects of stressors on ecosystem functioning and services in the Harbour are largely unknown. Sustainable management of this iconic natural system requires that knowledge gaps are addressed and translated into coherent environmental plans.
Impact of assimilating repeated subsurface temperature transects on state estimates of a western boundary current
Publisher: Frontiers Media SA
Date: 09-02-2023
DOI: 10.3389/FMARS.2022.1084784
Abstract: Western Boundary Currents and the eddies they shed are high priorities for numerical estimation and forecasting due to their economic, ecological and dynamical importance. However, the rapid evolution, complex dynamics and baroclinic structure that is typical of eddies and the relatively sparse s ling in western boundary currents leads to significant challenges in understanding the 3-dimensional structure of these boundary currents and mesoscale eddies. Here, we use Observing System Simulation Experiments (OSSEs) to explore the impact of assimilating synthetic subsurface temperature observations at a range of temporal resolutions, to emulate expendable bathythermograph transects with different repeat frequencies (weekly to quarterly). We explore the improvement in the representation of mesoscale eddies and subsurface conditions in a dynamic western boundary current system, the East Australian Current, with a data-assimilating regional ocean model. A characterisation of the spatial and temporal ocean variability spectrum demonstrates the potential for unders ling and aliasing by a lower s ling frequency. We find that assimilating subsurface temperature data with at least a weekly repeat time best improves subsurface representation of this dynamic, eddy-rich region. However, systemic biases introduced by the data assimilation system hinder the ability of the model to produce more accurate subsurface representation with fortnightly or monthly s ling. Removal of this bias may improve subsurface representation in eddy-rich regions with fortnightly or even less frequent observations. These results highlight the value of both increased subsurface observation density in regions of dynamic oceanography as well as continued development of data assimilation techniques in order to optimise the impact of existing observations.
Outstanding student paper awards
Publisher: American Geophysical Union (AGU)
Date: 29-07-2003
DOI: 10.1029/2003EO300005
East Australian Current
Publisher: Elsevier
Date: 2019
Editorial
Publisher: Informa UK Limited
Date: 04-10-2018
Physical and biogeochemical spatial scales of variability in the East Australian Current separation from shelf glider measurements
Publisher: Copernicus GmbH
Date: 31-03-2016
Abstract: Abstract. In contrast to physical processes, biogeochemical processes are inherently patchy in the ocean, which affects both the observational s ling strategy and the representativeness of sparse measurements in data assimilating models. In situ observations from multiple glider deployments are analysed to characterize spatial scales of variability in both physical and biogeochemical properties, using an empirical statistical model. We find that decorrelation ranges are strongly dependent on the balance between local dynamics and mesoscale forcing. The shortest horizontal (5–10 km) and vertical (45 m) decorrelation ranges are for chlorophyll a fluorescence, whereas those variables that are a function of regional ocean and atmosphere dynamics (temperature and dissolved oxygen) result in anisotropic patterns with longer ranges along (28–37 km) than across the shelf (8–19 km). Variables affected by coastal processes (salinity and coloured dissolved organic matter) have an isotropic range similar to the baroclinic Rossby radius (10–15 km).
Rate of coastal temperature rise adjacent to a warming western boundary current is non-uniform with latitude
Publisher: Wiley
Date: 24-09-2020
The rate of coastal temperature rise adjacent to a warming western boundary current is non-uniform with latitude
Publisher: Wiley
Date: 24-11-2020
Linking synoptic forcing and local mesoscale processes with biological dynamics off Ningaloo Reef
Publisher: American Geophysical Union (AGU)
Date: 03-2013
DOI: 10.1002/JGRC.20110
3D printed scaffold to monitor hanging drops on inverted microscopes
Publisher: JOSHA, GmbH
Date: 2019
Advances in and the Applicability of Machine Learning-Based Screening and Early Detection Approaches for Cancer: A Primer
Publisher: MDPI AG
Date: 26-01-2022
Abstract: Despite the efforts of the past decades, cancer is still among the key drivers of global mortality. To increase the detection rates, screening programs and other efforts to improve early detection were initiated to cover the populations at a particular risk for developing a specific malignant condition. These diagnostic approaches have, so far, mostly relied on conventional diagnostic methods and have made little use of the vast amounts of clinical and diagnostic data that are routinely being collected along the diagnostic pathway. Practitioners have lacked the tools to handle this ever-increasing flood of data. Only recently, the clinical field has opened up more for the opportunities that come with the systematic utilisation of high-dimensional computational data analysis. We aim to introduce the reader to the theoretical background of machine learning (ML) and elaborate on the established and potential use cases of ML algorithms in screening and early detection. Furthermore, we assess and comment on the relevant challenges and misconceptions of the applicability of ML-based diagnostic approaches. Lastly, we emphasise the need for a clear regulatory framework to responsibly introduce ML-based diagnostics in clinical practice and routine care.
Mean hydrography on the continental shelf from 26 repeat glider deployments along Southeastern Australia
Publisher: Springer Science and Business Media LLC
Date: 30-08-2016
Abstract: Since 2008, 26 glider missions have been undertaken along the continental shelf of southeastern Australia. Typically these missions have spanned the continental shelf on the inshore edge of the East Australian Current from 29.5–33.5 ° S. This comprehensive dataset of over 33,600 CTD profiles from the surface to within 10 m of the bottom in water depths ranging 25–200 m provides new and unprecedented high resolution observations of the properties of the continental shelf waters adjacent to a western boundary current, straddling the region where it separates from the coast. The region is both physically and biologically significant, and is also in a hotspot of ocean warming. We present gridded mean fields for temperature, salinity and density, but also dissolved oxygen and chlorophyll-a fluorescence indicative of phytoplankton biomass. This data will be invaluable for understanding shelf stratification, circulation, biophysical and bio-geochemical interactions, as well as for the validation of high-resolution ocean models or serving as teaching material.
Subsurface intensification of marine heatwaves off southeastern Australia: The role of stratification and local winds
Publisher: American Geophysical Union (AGU)
Date: 27-05-2017
DOI: 10.1002/2017GL073714
Cross-shelf dynamics in a western boundary current regime: Implications for upwelling
Publisher: American Meteorological Society
Date: 05-2013
Abstract: The cross-shelf dynamics up- and downstream of the separation of the South Pacific Ocean’s Western Boundary Current (WBC) are studied using two years of high-resolution velocity and temperature measurements from mooring arrays. The shelf circulation is dominated by the East Australian Current (EAC) and its eddy field, with mean poleward depth-integrated magnitudes on the shelf break of 0.35 and 0.15 m s−1 up- and downstream of the separation point, respectively. The high cross-shelf variability is analyzed though a momentum budget, showing a dominant geostrophic balance at both locations. Among the secondary midshelf terms, the bottom stress influence is higher upstream of the separation point while the wind stress is dominant downstream. This study investigates the response of the velocity and temperature cross-shelf structure to both wind and EAC intrusions. Despite the deep water (up to 140 m), the response to a dominant along-shelf wind stress forcing is a classic two-layer Ekman structure. During weak winds, the shelf encroachment of the southward current drives an onshore Ekman flow in the bottom boundary layer. Both the bottom velocity and the resultant bottom cross-shelf temperature gradient are proportional to the magnitude of the encroaching current, with similar linear regressions up- and downstream of the WBC separation. The upwelled water is then subducted below the EAC upstream of the separation point. Such current-driven upwelling is shown to be the dominant driver of cold water uplift in the EAC-dominated region, with significant impacts expected on nutrient enrichment and thus on biological productivity.
Update on Australia's National Reference Stations
Publisher: IEEE
Date: 09-2010
The Importance of Connected Ocean Monitoring Knowledge Systems and Communities
Publisher: Frontiers Media SA
Date: 14-06-2019
Oceanic Circulation Drives the Deepest and Longest Marine Heatwaves in the East Australian Current System
Publisher: American Geophysical Union (AGU)
Date: 07-09-2021
DOI: 10.1029/2021GL094785
Abstract: Although the impacts of marine heatwaves (MHWs) can extend well below the ocean surface, little is known about how oceanic and atmospheric forcings control their vertical structure. Here, we relate the MHW drivers to their sub‐surface characteristics in different dynamical regimes including the East Australia Current. We detect MHWs in the depth‐dependent surface mixed layer over 30‐years and use a heat budget to identify the dominant mechanisms driving them. We show that MHWs in the Western Boundary Current (WBC) jet are predominantly driven by air‐sea heatflux whilst in the WBC extension, MHWs are advection‐driven. The deepest and longest MHWs are advection‐driven and are more prevalent in autumn and winter. Surface (latent) flux‐driven MHWs are shallower and occur predominantly in summer. Demonstrating how MHW characteristics are linked to their drivers facilitates their prediction through driver diagnosis, especially below the surface where observations are sparse and ecological impact is high.
Mean hydrography on the continental shelf from 26 repeat glider deployments along Southeastern Australia
Publisher: Australian Ocean Data Network
Date: 2016
The formation of a cold-core eddy in the East Australian Current
Publisher: Elsevier BV
Date: 02-2016
IMOS National Reference Stations: A Continental-Wide Physical, Chemical and Biological Coastal Observing System
Publisher: Public Library of Science (PLoS)
Date: 17-12-2014
Observations of divergence and upwelling around Point Loma, California
Publisher: American Geophysical Union (AGU)
Date: 04-2005
DOI: 10.1029/2004JC002662
Connectivity of Estuaries
Publisher: Elsevier
Date: 2012
Mesoscale circulation determines broad spatio-temporal settlement patterns of lobster
Publisher: Public Library of Science (PLoS)
Date: 02-2019
Finding a proxy for wind stress over the coastal ocean
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF11250
Abstract: Wind stress forcing is a critical driver of oceanographic processes. In the absence of over-ocean wind measurements, re-analysis products and over-land measurements are often used. The present paper compares a unique wind-data series from an ocean mooring with two re-analysis products and data from six over-land sites in Sydney, Australia, to determine whether these data can infer over-ocean wind conditions. Four oceanographic moorings are located here however, over-ocean meteorological observations are no longer available. Correlations between over-ocean and over-land sites wind stress were .8, whereas for re-analysis products, correlations ranged from 0.28 to 0.72. Re-analysis products were unable to resolve variability at the over-ocean site with periods shorter than 2 days, indicating that they are not appropriate wind proxies for the coastal ocean. Somewhat counter-intuitively, our results showed that proximity of over-land sites to the over-ocean site does not necessarily imply the highest correlation or the lowest error and careful site selection is required. An upwelling study showed that wind observations from selected over-land sites can accurately represent isotherm uplift in the coastal ocean. Threshold wind stress values that uplift isotherms at these over-land sites are provided, along with a recommendation for the use of the over-land site that best represents over-ocean wind conditions in this region.
Efficacy of Feedforward and LSTM Neural Networks at Predicting and Gap Filling Coastal Ocean Timeseries: Oxygen, Nutrients, and Temperature
Publisher: Frontiers Media SA
Date: 03-05-2021
DOI: 10.3389/FMARS.2021.637759
Abstract: Ocean data timeseries are vital for a erse range of stakeholders (ranging from government, to industry, to academia) to underpin research, support decision making, and identify environmental change. However, continuous monitoring and observation of ocean variables is difficult and expensive. Moreover, since oceans are vast, observations are typically sparse in spatial and temporal resolution. In addition, the hostile ocean environment creates challenges for collecting and maintaining data sets, such as instrument malfunctions and servicing, often resulting in temporal gaps of varying lengths. Neural networks (NN) have proven effective in many erse big data applications, but few oceanographic applications have been tested using modern frameworks and architectures. Therefore, here we demonstrate a “proof of concept” neural network application using a popular “off-the-shelf” framework called “TensorFlow” to predict subsurface ocean variables including dissolved oxygen and nutrient (nitrate, phosphate, and silicate) concentrations, and temperature timeseries and show how these models can be used successfully for gap filling data products. We achieved a final prediction accuracy of over 96% for oxygen and temperature, and mean squared errors (MSE) of 2.63, 0.0099, and 0.78, for nitrates, phosphates, and silicates, respectively. The temperature gap-filling was done with an innovative contextual Long Short-Term Memory (LSTM) NN that uses data before and after the gap as separate feature variables. We also demonstrate the application of a novel dropout based approach to approximate the Bayesian uncertainty of these temperature predictions. This Bayesian uncertainty is represented in the form of 100 monte carlo dropout estimates of the two longest gaps in the temperature timeseries from a model with 25% dropout in the input and recurrent LSTM connections. Throughout the study, we present the NN training process including the tuning of the large number of NN hyperparameters which could pose as a barrier to uptake among researchers and other oceanographic data users. Our models can be scaled up and applied operationally to provide consistent, gap-free data to all data users, thus encouraging data uptake for data-based decision making.
A water mass classification approach to tracking variability in the East Australian Current
Publisher: Frontiers Media SA
Date: 03-06-2020
Daily Subsurface Ocean Temperature Climatology Using Multiple Data Sources: New Methodology
Publisher: Frontiers Media SA
Date: 30-07-2020
Strengthened currents override the effect of warming on lobster larval dispersal and survival
Publisher: Wiley
Date: 06-11-2015
DOI: 10.1111/GCB.13063
Long-term trends in the East Australian Current separation latitude and eddy driven transport
Publisher: American Geophysical Union (AGU)
Date: 07-2014
DOI: 10.1002/2014JC010071
Future ocean temperature impacting the survival prospects of post-larval spiny lobsters
Publisher: Elsevier BV
Date: 04-2020
Entrainment and development of larval fish assemblages in two contrasting cold core eddies of the East Australian Current system
Publisher: Inter-Research Science Center
Date: 10-03-2022
DOI: 10.3354/MEPS13982
Abstract: Cyclonic eddies are erse in their size, age, upwelling and behaviour, which has significant implications for fisheries production and connectivity when they interact with the continental shelf. To ascertain coastal entrainment by eddies, we compared the larval fish community of 2 contrasting cyclonic eddies in 3 depth strata (0-5, 5-50, 50-100 m), and with the adjacent shelf community. The frontal cyclonic eddy was smaller and younger than the mesoscale cyclonic eddy. A larval fish entrainment index, based on the ratio of coastal to oceanic taxa, revealed the relative abundance of coastal larvae entrained into the upper mixed layer of the frontal eddy, consistent with published numerical modelling studies of similar eddies. The frontal eddy had a high abundance of commercially important coastal taxa entrained from the inner shelf. However, the adjacent inner shelf water and putative location for frontal eddy formation had recently been displaced by the East Australian Current, resulting in the larval fish community being dominated by oceanic taxa. The spatial and temporal dynamics of coastal entrainment into the larger, older cyclonic eddy and the adjacent shelf region were revealed by mixtures of coastal and oceanic taxa in each of the depth strata. The larger cyclonic eddy had a higher biomass of zooplankton, indicating the cumulative effects of eddy age and production. Eddies which interact with the shelf enable cross-shelf mixing and may contribute to coastal fisheries.
Dynamics of Interannual Eddy Kinetic Energy Modulations in a Western Boundary Current
Publisher: American Geophysical Union (AGU)
Date: 09-10-2021
DOI: 10.1029/2021GL094115
Abstract: Among Western Boundary Currents, the East Australian Current (EAC) has a more energetic eddy field relative to its mean flow, however, the relationship between upstream transport and downstream eddy kinetic energy (EKE) is still unclear. We investigate the modulation of downstream EKE in the EAC's typical separation region (Tasman EKE Box) (33. S–36. S) based on a long‐term (22‐year), high‐resolution (2.5–6 km) model simulation and satellite altimeter observations from 1994 to 2016. Our results show that the poleward EAC transport at S leads the EKE in the Tasman EKE Box by 93–118 days. Barotropic instabilities are the primary source of EKE, and they control EKE variability in the EAC system. Anticyclonic eddies shed from the EAC dominate from S– S during high‐EKE periods, but in low‐EKE periods anticyclonic eddies penetrate even further south by .
Drivers of upper ocean heat content extremes around New Zealand revealed by Adjoint Sensitivity Analysis
Publisher: Frontiers Media SA
Date: 28-10-2022
DOI: 10.3389/FCLIM.2022.980990
Abstract: Marine heatwaves can have devastating ecological and economic impacts and understanding what drives their onset is crucial to achieving improved prediction. A key knowledge gap exists around the subsurface structure and temporal evolution of MHW events in continental shelf regions, where impacts are most significant. Here, we use a realistic, high-resolution ocean model to identify marine heatwaves using upper ocean heat content (UOHC) as a diagnostic metric. We show that, embedded in the inter-annual variability of UOHC across the Tasman Sea, regional UOHC around New Zealand varies at short temporal and spatial scales associated with local circulation which drives the onset of extreme events with median duration of 5–20 days. Then, using a novel application of Adjoint Sensitivity Analysis, we diagnose the regional drivers of extreme UOHC events and their 3-dimensional structure. We compute the sensitivity of UOHC to changes in the ocean state and atmospheric forcing over the onset of MHW events using ensembles of between 34 and 64 MHW events across 4 contrasting regions over a 25-year period. The results reveal that changes in regional UOHC on short (5-day) timescales are largely driven by local ocean circulation rather than surface heat fluxes. Where the circulation is dominated by boundary currents, advection of temperature in the mixed layer dominates the onset of extreme UOHC events. Higher magnitude MHW events are typically associated with shallower mixed layer and thermocline depths, with higher sensitivity to temperature changes in the upper 50–80 m. On the west coast, where boundary currents are weak, UOHC extremes are sensitive to density changes in the upper 1,000 m and likely caused by downwelling winds. Our results highlight the importance of understanding the different temporal and spatial scales of UOHC variability. Understanding the local circulation associated with heat content extremes is an important step toward accurate MHW predictability in economically significant shelf seas.
Temperate shelf water dispersal by Australian boundary currents: Implications for population connectivity
Publisher: Wiley
Date: 02-2013
Why the Mixed Layer Depth Matters When Diagnosing Marine Heatwave Drivers Using a Heat Budget Approach
Publisher: Frontiers Media SA
Date: 25-03-2022
DOI: 10.3389/FCLIM.2022.838017
Abstract: Marine heatwaves (MHWs) are extreme warming events that can result in significant damage to marine ecosystems and local economies. The primary drivers of these events have been frequently studied using an upper ocean heat budget. However, various surface mixed layer (SML) depths have been used with little attention paid to the impact of the depth chosen on heat budget term estimates. We analyse MHW drivers in two dynamically contrasting regions off the east coast of Australia (East Australian Current extension) and the west coast of New Zealand over a 30-year period (1985–2014, inclusive). We compare the magnitude of the air-sea heatflux and advection terms in a volume-averaged heat budget using three different SML depth estimates. We show that the SML depth over which the heat budget is calculated has direct consequences on the identification of MHW dominant drivers. The air-sea heatflux term is lified when the SML depth is underestimated and d ened when overestimated. The variation in the magnitude of the advection term is dependent on the barotropic or baroclinic structure of the currents. We, also, show that the impact on MHW driver classification is both temporally and regionally dependent. Generally, a deep SML estimate results in more MHWs being classified as advection and less classified as air-sea heatflux-driven. However, during the cool months, a shallow estimate produces the opposite pattern and to a varying degree of intensity depending on the region's dynamics. Use of daily and spatially variable SML depth in a heat budget calculation allows the comparison between regions with different dynamics influencing the mixed layer depth. These results show that when using a heat budget approach to explore marine heatwaves over extended time and space (e.g., regions and seasons), it is imperative to consider the temporal and spatial variability in the SML depth.
How does 4DVar data assimilation affect the vertical representation of mesoscale eddies? A case study with observing system simulation experiments (OSSEs) using ROMS v3.9
Publisher: Copernicus GmbH
Date: 04-01-2023
Abstract: Abstract. Accurate estimates and forecasts of ocean eddies in key regions such as western boundary currents are important for weather and climate, biology, navigation, and search and rescue. The dynamic nature of mesoscale eddies requires data assimilation to produce accurate eddy timings and locations in ocean model simulations. However, data assimilating models are rarely assessed below the surface due to a paucity of observations hence it is not clear how data assimilation impacts the subsurface eddy structure. Here, we use a suite of observing system simulation experiments to show how the subsurface representation of eddies is changed within data assimilating simulations even when assimilating nearby observations. We examine in detail two possible manifestations of how the data assimilation process impacts three-dimensional eddy structure, namely, by producing overly active baroclinic instability and through inaccurate vertical mode structure. Therefore, in DA simulations, subsurface temperature structures can be too deep and too warm, particularly in dynamic eddy features. Our analyses demonstrate the need for further basic research in ocean data assimilation methodologies to improve the representation of the subsurface ocean structure.
Lagrangian characterization of nitrate supply and episodes of extreme phytoplankton blooms in the Great Australian Bight
Publisher: Copernicus GmbH
Date: 17-03-2016
DOI: 10.5194/BG-2016-53
Abstract: Abstract. Phytoplankton growth is the foundation for energy transfer into higher trophic levels, influences climate by the uptake of atmospheric CO2, and plays an important role in nutrient cycling. Here we use a novel lagrangian approach to characterize the nitrate supply to the Great Australian Bight, identify episodes of extreme phytoplankton blooms and ascertain the origin of the nitrate sources that fuel them. We find that 55 % of nitrate used by phytoplankton enters the GAB in the upper 100 m and that 88 % originates locally from a region between the GAB and the Sub Antarctic Front, rather than from more remote oceans thus, most of the nitrate is recycled locally. Our results show extreme phytoplankton blooms have an annual periodicity, peaking in the Austral autumn when the mixed layer deepens. This suggests that stratification erosion is key supplying nutrients into the euphotic zone and triggering these episodes.
A Modeling Study of the Climatological Current Field and the Trajectories of Upwelled Particles in the East Australian Current
Publisher: American Meteorological Society
Date: 12-2003
Using high-resolution ocean timeseries data to give context to long term hydrographic sampling off Port Hacking, NSW, Australia
Publisher: IEEE
Date: 09-2011
Impact of Mesoscale Circulation on the Structure of River Plumes During Large Rainfall Events Inshore of the East Australian Current
Publisher: Frontiers Media SA
Date: 03-03-2022
DOI: 10.3389/FMARS.2022.815348
Abstract: Estuarine outflow can have a significant impact on physical and ecological systems in the coastal ocean. Along southeastern Australia, inshore of the East Australian Current, the shelf is narrow, the coastal circulation is advection dominated, and river estuarine outflow tends to be low, hence river plumes have largely been ignored. For these reasons, we lack an understanding of the spatial and temporal evolution of river plumes during large rainfall events (which are projected to increase in frequency and intensity), and the interaction of the mesoscale circulation with the estuarine outflow remains to be explored. Using a high-resolution (750 m) hydrodynamic model, we simulate idealized plumes from 4 estuaries during three different mesoscale circulation scenarios and investigate the spatial and temporal evolution of the estuarine outflow under two contrasting rainfall events (normal and large). We explore the plume from the largest of the 4 rivers, the Hawkesbury River, to understand the impact of the mesoscale circulation. During the first EAC mode, the plume spreads both northward and southeastward. The offshore spread of the plume is the largest in this scenario (~12.5 km east of the river mouth) in the wet event. In the second EAC mode, this plume dispersal is toward the north and east, driven by the proximity of a cyclonic eddy on the shelf, with an eastward extension of 11 km. In the third EAC mode, most of this river plume spreads southward with some to the north, again dictated by the position of the cyclonic eddy. The cross-shelf dispersal is a minimum of 9.5 km from the river mouth. It takes around 6 days for the freshwater spatial extent of the plume in the wet event to return to the base case. These results show the importance of mesoscale EAC circulation on the shelf circulation when considering river plumes dispersal. Knowledge of the ultimate fate of riverborne material, dilution and cumulative effects will enable better environmental management of this dynamic region for the local government.
Combined biophysical and genetic modelling approaches reveal new insights into population connectivity of New Zealand green-lipped mussels
Publisher: Frontiers Media SA
Date: 29-09-2022
DOI: 10.3389/FMARS.2022.971209
Abstract: Understanding how ocean currents affect larval transport is crucial for understanding population connectivity in sessile marine invertebrates whose primary dispersal opportunity occurs during the pelagic larval stage. This study used Lagrangian particle tracking experiments to examine population connectivity in New Zealand green-lipped mussels ( Perna canaliculus ) at the national scale. Predicted patterns of larval dispersal were compared to published multi-locus microsatellite data of observed population genetic structure. Estimates of oceanographic circulation correlated significantly with F ST, and we conclude that hydrodynamic processes are important in driving genetic connectivity. However, no evidence was found for an oceanographic barrier to gene flow south of Cook Strait, an important feature of genetic structure observed across several marine invertebrate species. Discrepancies between genetic and biophysical data may be explained by several factors including the different timescales of connectivity described by the two methods and the impact of localised ecological conditions and corresponding adaptations in genetic structure not captured by the bipohysical model. Population genetic analyses provide empirical data on realised connectivity and Lagrangian particle tracking experiments reveal information about directionality and asymmetry of connections that often cannot be determined by molecular analyses alone, thus a multidisciplinary approach is recommended.
Observation Impact in a Regional Reanalysis of the East Australian Current System
Publisher: American Geophysical Union (AGU)
Date: 10-2018
DOI: 10.1029/2017JC013685
WEST: A northern California study of the role of wind-driven transport in the productivity of coastal plankton communities
Publisher: Elsevier BV
Date: 12-2006
Interactions between seasonality and oceanic forcing drive the phytoplankton variability in the tropical-temperate transition zone (~ 30°S) of Eastern Australia
Publisher: Elsevier BV
Date: 04-2015
Global Perspectives on Observing Ocean Boundary Current Systems
Publisher: Frontiers Media SA
Date: 08-08-2019
OceanGliders: A Component of the Integrated GOOS
Publisher: Frontiers Media SA
Date: 02-10-2019
Abstract: The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health, and Operational Services. It brings together marine scientists and engineers operating gliders around the world: (1) to observe the long-term physical, biogeochemical, and biological ocean processes and phenomena that are relevant for societal applications and, (2) to contribute to the GOOS through real-time and delayed mode data dissemination. The OceanGliders program is distributed across national and regional observing systems and significantly contributes to integrated, multi-scale and multi-platform s ling strategies. OceanGliders shares best practices, requirements, and scientific knowledge needed for glider operations, data collection and analysis. It also monitors global glider activity and supports the dissemination of glider data through regional and global databases, in real-time and delayed modes, facilitating data access to the wider community. OceanGliders currently supports national, regional and global initiatives to maintain and expand the capabilities and application of gliders to meet key global challenges such as improved measurement of ocean boundary currents, water transformation and storm forecast.
Characteristic ichthyoplankton taxa in the separation zone of the East Australian Current: Larval assemblages as tracers of coastal mixing
Publisher: Elsevier BV
Date: 03-2011
Quantifying Cross-Shelf Transport in the East Australian Current System: A Budget-Based Approach
Publisher: American Meteorological Society
Date: 10-2022
Abstract: Cross-shelf transport plays an important role in the heat, salt, and nutrient budgets of the continental shelf. In this study, we quantify cross-shelf volume transport and explore its dynamics within a high-resolution (2.5–6 km) regional ocean model of the East Australian Current (EAC) System, a western boundary current with a high level of mesoscale eddy activity. We find that the largest time-mean cross-shelf flows ( Sv per 100 km 1 Sv ≡ 10 6 m 3 s −1 ) occur inshore of the coherent western boundary current, between 26° and 30°S, while the strongest time-varying flows occur in the EAC southern extension, poleward of 32°S, associated with mesoscale eddies. Using a novel diagnostic equation derived from the momentum budget we show that the cross-shelf transport is dominated by the baroclinic and geostrophic component of the velocities, as the EAC jet is relatively free to flow over the variable shelfbreak topography. However, topographic interactions are also important and act through the bottom pressure torque term as a secondary driver of cross-shelf transport. The importance of topographic interaction also increases in shallower water inshore of the coherent jet. Downstream of separation, cross-shelf transport is more time-varying and associated with the interaction of mesoscale eddies with the shelf. The identification of the change in nature and drivers of cross-shelf transport in eddy versus jet dominated regimes may be applicable to understanding cross-shelf transport dynamics in other boundary current systems. Cross-shelf transport, i.e., the movement of water from the open ocean on or off the continental shelf, is not reported often as it is difficult to measure and model. We demonstrate a simple but effective method to do this and, using an ocean model, apply it to the East Australian Current System and show what drives it. The results show two distinct regimes, which differ depending on which part of the current system you are in. Our results help to place observations of cross-shelf transport in better context and provide a framework within which to consider the transport of other things such as heat and carbon from the open ocean to the continental shelf.
The effect of surface flooding on the physical-biogeochemical dynamics of a warm-core eddy off southeast Australia
Publisher: Elsevier BV
Date: 03-2011
Developing an Integrated Ocean Observing System for New Zealand
Publisher: Frontiers Media SA
Date: 26-03-2019
Numerical modelling of the Sydney Harbour Estuary, New South Wales: Lateral circulation and asymmetric vertical mixing
Publisher: Elsevier BV
Date: 02-2019
Oceanographic conditions associated with white shark (Carcharodon carcharias) habitat use along eastern Australia
Publisher: Inter-Research Science Center
Date: 04-02-2021
DOI: 10.3354/MEPS13572
Abstract: Management of species with wide-ranging migrations is a complex issue, made more challenging when the species is both protected and poses a risk to humans. Understanding the oceanic conditions associated with shark habitat use can help develop mitigation strategies or warning systems that meet both conservation and human safety objectives. Using satellite tracks from 77 juvenile and sub-adult white sharks tagged over 10 yr, we modelled in idual movement patterns using hidden Markov models and applied generalised additive (mixed) models to explore correlations between movement patterns (presence-absence, habitat selection and behavioural state) and oceanographic and bathymetric variables. White sharks used the whole of the continental shelf, down to depths of 350 m on the continental slope. Sharks were present over a wide range of sea surface temperatures (SSTs 10-27°C), with the highest probability of occurring at ~20°C. However, the number of average daily tag positions was greatest when SST was between 14 and 18°C, and sharks were more likely to exhibit area-restricted movement when SST was between ~19 and 23°C. Sharks were more likely to be present and selected habitats in productive areas with moderate to high surface chl a concentrations as well as thermal and productivity fronts. Although mesoscale eddies did not influence the likelihood of in iduals being present in an area, there was a higher density of sharks in cold-core eddies compared to warm-core eddies. This study indicates that white shark presence and dispersal may be linked, perhaps via prey distribution, to oceanic conditions, potentially assisting development of suitable shark bite mitigation strategies.
Relative impact of seasonal and oceanographic drivers on surface chlorophyll a along a Western Boundary Current
Publisher: Elsevier BV
Date: 2014
Moana Ocean Hindcast – a > 25-year simulation for New Zealand waters using the Regional Ocean Modeling System (ROMS) v3.9 model
Publisher: Copernicus GmbH
Date: 09-01-2023
Abstract: Abstract. Here we present the first open-access long-term 3D hydrodynamic ocean hindcast for the New Zealand ocean estate. The 28-year 5 km×5 km resolution free-running ocean model configuration was developed under the umbrella of the Moana Project, using the Regional Ocean Modeling System (ROMS) version 3.9. It includes an improved bathymetry, spectral tidal forcing at the boundaries and inverse-barometer effect usually absent from global simulations. The continuous integration provides a framework to improve our understanding of the ocean dynamics and connectivity, as well as identify long-term trends and drivers for particular processes. The simulation was compared to a series of satellite and in situ observations, including sea surface temperature (SST), sea surface height (SSH), coastal water level and temperature stations, moored temperature time series, and temperature and salinity profiles from the CORA5.2 (Coriolis Ocean database for ReAnalysis) dataset – including Argo floats, XBTs (expendable bathythermographs) and CTD (conductivity–temperature–depth) stations. These comparisons show the model simulation is consistent and represents important ocean processes at different temporal and spatial scales, from local to regional and from a few hours to years including extreme events. The root mean square errors are 0.11 m for SSH, 0.23 ∘C for SST, and ∘C and 0.15 g kg−1 for temperature and salinity profiles. Coastal tides are simulated well, and both high skill and correlation are found between modelled and observed sub-tidal sea level and water temperature stations. Moreover, cross-sections of the main currents around New Zealand show the simulation is consistent with transport, velocity structure and variability reported in the available literature. This first multi-decadal, high-resolution, open-access hydrodynamic model represents a significant step forward for ocean sciences in the New Zealand region.
Boundary Ocean Observation Network for the Global South
Publisher: Marine Technology Society
Date: 05-2021
DOI: 10.4031/MTSJ.55.3.30
Abstract: Abstract The UN Decade of Ocean Science for Sustainable Development should establish a Boundary Ocean Observing Network (BOON) for the Global South (GS). The BOON is part of the OceanGlider Program, which is part of the Global Ocean Observing System (GOOS). The BOON is a network of established timeseries transects collecting long-term data sets. Timeseries are critical for making immediate operational decisions and for identifying long-term trends of anthropogenic global environmental change. The network has proven important enough to continue observations and expand them. Due to resource and expertise limitations, expanded locations are in similar locations. The UN should build on this success and establish a BOON for the Global South. The same benefits will be garnered by countries and regions that have been missing out. Increased observation coverage will benefit humanity, improving understanding of the Ocean-Climate System, e.g. leading to improved climate prediction models. The UN will facilitate activities to realize a BOON for the Global South including: coordinating local scientists, partnering scientific and technical experts with local scientists, identifying new affordable and easy-to-operate technologies, channeling funds for initial and ongoing costs, and building a framework to continue the BOON-GS long after the Ocean Science Decade.
An International Perspective on Graduate Education in Physical Oceanography
Publisher: The Oceanography Society
Date: 2003
Mesoscale Circulation Controls Chlorophyll Concentrations in the East Australian Current Separation Zone
Publisher: American Geophysical Union (AGU)
Date: 04-2023
DOI: 10.1029/2022JC019361
Abstract: Understanding the distribution of chlorophyll on the continental shelves adjacent to western boundary currents is important, both from an ecosystem perspective, as well as for their role as a net sink of atmospheric CO 2 . However, in‐situ observations of chlorophyll in these dynamic regions are rare. Here, using more than a decade of underwater glider observations from 29 deployments in the East Australian Current (EAC) system, we examine the effect of the mesoscale western boundary current (WBC) circulation on chlorophyll distribution across the shelf. The extensive hydrographic dataset reveals that the mode of boundary current separation has a strong persistent spatial influence on both the stratification and chlorophyll distribution on the shelf between 31.5° and 34°S, a productive area adjacent to the EAC separation zone. We identify that subsurface chlorophyll maxima are common, and their depth and strength is dictated by the offshore mesoscale circulation associated with the WBC separation. The vertical chlorophyll distribution is modulated by the combination of the seasonal cycle and the sporadic influence of mesoscale eddies associated with WBC jet separation. Of the three dominant WBC separation scenarios, eddy dipoles result in shelf waters that are on average more stratified, have higher chlorophyll values, and a deeper chlorophyll maximum compared to other circulation modes. These results suggest that it is necessary to consider the influence of WBC dynamics on chlorophyll concentrations for accurate estimates of atmospheric CO 2 uptake.
Temperature variability in a shallow, tidally isolated coral reef lagoon
Publisher: American Geophysical Union (AGU)
Date: 12-2010
DOI: 10.1029/2009JC006023
Abstract: Temperature data collected in the shallow, tidally isolated reef flat/lagoon of Lady Elliot Island off Queensland, Australia, show marked variability under solar and tidal forcing. Sea level drops below the height of the protective lagoon rim for a few hours during low tide, effectively isolating the remaining water. Because the lagoon is shallow, its temperature change (from diurnal solar forcing and cooling) is lified. We develop a simple analytical model to predict the time evolution of mean lagoon temperature, beginning with a well‐mixed control volume. This approach highlights the asymmetric flood/ebb physics of tidally isolated lagoons. After discussing the response of this model, we compare it with results from two idealized numerical simulations that illustrate differing aspects of lagoon temperature variability under “potential flow” and “prevailing current” situations. The conceptual model captures the essence of lagoon temperature variability and underscores the importance of solar‐lunar phasing. However, because of the well‐mixed assumption, it cannot reproduce sudden temperature transitions associated with new incoming water masses. Observations show that a slowly progressing thermal wave inundates the lagoon on rising tides. This wave is similar to our “potential flow” simulation in that it is approximately radially symmetric. On the other hand, it appears to advectively replace resident lagoon water, similar to our “prevailing current” simulations. We attempt to account for this behavior with a simple “frontal” modification to our conceptual model. Results show that this frontal model is able to capture the sudden temperature transitions present in the data and offers improved predictive capabilities over the well‐mixed model.
A comparison of observed upwelling mechanisms off the east coast of Australia
Publisher: Elsevier BV
Date: 11-2002
Sustained Ocean Observing along the Coast of Southeastern Australia
Publisher: Elsevier
Date: 2015
On the factors influencing the development of sporadic upwelling in the Leeuwin Current system
Publisher: American Geophysical Union (AGU)
Date: 07-2013
DOI: 10.1002/JGRC.20242
Tick‐borne encephalitis virus and West‐Nile fever virus as causes of serous meningitis of unknown origin in Kazakhstan
Publisher: Wiley
Date: 23-03-2022
DOI: 10.1111/ZPH.12941
Abstract: Flaviviruses are a family of viruses that cause many diseases in humans. Their similarity in the antigenic structure causes a cross‐reaction, which complicates the precise diagnostic of disease causing agents. Tick‐borne encephalitis virus (TBEV), a member of the flavivirus family, is the cause of tick‐borne encephalitis (TBE). Worldwide the awareness of this disease is raising, however, in many countries such as the Republic of Kazakhstan (KZ) there is a lack of serological investigation of flaviviruses in humans. In our study, we focused on two TBE endemic regions of KZ (East Kazakhstan Oblast (EKO) and Almaty (AO)) and a region where TBE cases were registered only since 2010 (Akmola Oblast (AkO)). In KZ, up to 400 cases of serous meningitis of unknown origin were registered annually in the period from 2017 to 2019. Our goals were to calculate the prevalence of antibodies against TBEV in patients with suspected meningitis. We collected 179 sera and 130 cerebrospinal fluid (CSF) s les from patients and included a questionnaire with focus on socio‐demographical factors and observed tick bites. The human s les were tested with TBEV and West‐Nile fever virus (WNFV) IgM and IgG ELISA, by immunofluorescence assay using a flavivirus biochip, and TBEV‐specific real‐time RT‐PCR. We found TBEV and WNFV antibodies in 31 s les by serological and molecular techniques. Seven serum s les out of 31 showed TBEV‐specific antibodies, and three serum pairs had WNFV antibodies. Correlating the serological results with the information gained from the questionnaires it becomes apparent that the number of tick bites is a significant factor for a TBEV infection. This result has an impact on diagnostic in KZ and physicians should be aware that both flaviviruses play a role for serous meningitis of unknown origin in KZ.
Characterizing frontal eddies along the E ast A ustralian C urrent from HF radar observations
Publisher: American Geophysical Union (AGU)
Date: 05-2017
DOI: 10.1002/2016JC012171
Abstract: The East Australian Current (EAC) dominates the ocean circulation along south‐eastern Australia, however, little is known about the submesoscale frontal instabilities associated with this western boundary current. One year of surface current measurements from HF radars, in conjunction with mooring and satellite observations, highlight the occurrence and propagation of meanders and frontal eddies along the inshore edge of the EAC. Eddies were systematically identified using the geometry of the high spatial resolution (∼1.5 km) surface currents, and tracked every hour. Cyclonic eddies were observed irregularly, on average every 7 days, with inshore radius ∼10 km. Among various forms of structures, frontal eddies associated with EAC meanders were characterized by poleward advection speeds of ∼0.3–0.4 m/s, migrating as far as 500 km south, based on satellite imagery. Flow field kinematics show that cyclonic eddies have high Rossby numbers (0.6–1.9) and enhance particle dispersion. Patches of intensified surface ergence at the leading edge of the structures are expected to generate vertical uplift. This is confirmed by subsurface measurements showing temperature uplift of up to 55 m over 24 h and rough estimates of vertical velocities of 10s of meters per day. While frontal eddies propagate through the radar domain independently of local wind stress, upfront wind can influence their stalling and growth, and can also generate large cold core eddies through intense shear. Such coherent structures are a major mechanism for the transport and entrainment of nutrient rich coastal or deep waters, influencing physical and biological dynamics, and connectivity over large distances.
Evaluation of four global ocean reanalysis products for New Zealand waters–A guide for regional ocean modelling
Publisher: Informa UK Limited
Date: 22-01-2020
Phytoplankton composition under contrasting oceanographic conditions: Upwelling and downwelling (Eastern Australia)
Publisher: Elsevier BV
Date: 03-2014
NSW-IMOS: An Integrated Marine Observing System for Southeastern Australia
Publisher: IOP Publishing
Date: 08-2010
Seasonal stratification and complex local dynamics control the sub-surface structure of marine heatwaves in Eastern Australian coastal waters
Publisher: Springer Science and Business Media LLC
Date: 09-2023
The Rate of Coastal Temperature Rise Adjacent to a Warming Western Boundary Current is Nonuniform with Latitude
Publisher: American Geophysical Union (AGU)
Date: 03-02-2021
DOI: 10.1029/2020GL090751
Abstract: Western boundary currents (WBCs) have intensified and become more eddying in recent decades due to the spin‐up of the ocean gyres, resulting in warmer open ocean temperatures. However, relatively little is known of how WBC intensification will affect temperatures in adjacent continental shelf waters where societal impact is greatest. We use the well‐observed East Australian Current (EAC) to investigate WBC warming impacts on shelf waters and show that temperature increases are nonuniform in shelf waters along the latitudinal extent of the EAC. Shelf waters poleward of 32°S are warming more than twice as fast as those equatorward of 32°S. We show that nonuniform shelf temperature trends are driven by an increase in lateral heat advection poleward of the WBC separation, along Australia's most populous coastline. The large‐scale nature of the process indicates that this is applicable to WBCs broadly, with far‐reaching biological implications.
Assessing the Impact of Nontraditional Ocean Observations for Prediction of the East Australian Current
Publisher: American Geophysical Union (AGU)
Date: 12-2020
DOI: 10.1029/2020JC016580
Abstract: Accurate forecasting of ocean currents in dynamic regions remains a critical challenge due to the sparsity of observations in global ocean observing networks and the limited resolution of present‐day regional ocean models. Lately, traditional observing platforms have been complemented by newly available data streams capable of s ling at higher spatial and/or temporal resolutions in dynamically significant regions in near‐real time. However, the relative merits and trade‐offs of incorporating these “nontraditional” observations into ocean state estimates have not been thoroughly investigated. Here, we perform a detailed statistical and dynamical comparison of two high‐resolution reanalysis products assimilating different combinations of traditional and nontraditional observations in the East Australian Current (EAC) system, a vigorous western boundary current. We show that sea‐surface height and temperature are well‐constrained by satellite measurements however, below the surface, a reanalysis incorporating fully available observations better represents the ocean state. The core of the EAC jet is effectively constrained by subsurface observations from deep water moorings upstream of jet separation, while radar‐derived nearshore surface velocities in the separation zone are found to resolve the submesoscale cyclonic band inshore of the EAC. Cost function sensitivity analysis of both products reveals excessive model adjustment at depth causing the reanalyzes to overestimate alongshore transport relative to a 22‐year freely evolving simulation. Overall, the assimilation of nontraditional observations delivers marked improvement in representing dynamical features of the EAC. However, this improvement is not as pronounced in the model forecast due to the introduction of nonphysical dynamics or forcing, suggesting that other improvements such as increased model resolution are required.
Environmental drivers of abundance and residency of a large migratory shark, Carcharhinus leucas, inshore of a dynamic western boundary current
Publisher: Inter-Research Science Center
Date: 18-07-2019
DOI: 10.3354/MEPS13052
Role of apoptosis in the development of autosomal dominant polycystic kidney disease (ADPKD).
Publisher: Springer Science and Business Media LLC
Date: 30-05-2017
DOI: 10.1007/S00441-017-2628-6
Abstract: Autosomal dominant polycystic kidney disease (ADPKD) is a widespread genetic disorder in the Western world and is characterized by cystogenesis that often leads to end-stage renal disease (ESRD). Mutations in the pkd1 gene, encoding for polycystin-1 (PC1) and its interaction partner pkd2, encoding for polycystin-2 (PC2), are the main drivers of this disease. PC1 and PC2 form a multiprotein membrane complex at cilia sites of the plasma membrane and at intracellular membranes. This complex mediates calcium influx and stimulates various signaling pathways regulating cell survival, proliferation and differentiation. The molecular consequences of pkd1 and pkd2 mutations are still a matter of debate. In particular, the ways in which the cysts are initially formed and progress throughout the disease are unknown. The mechanisms proposed to play a role include enhanced cell proliferation, increased apoptotic cell death and diminished autophagy. In this review, we summarize our current understanding about the contribution of apoptosis to cystogenesis and ADPKD. We present the animal models and the tools and methods that have been created to analyze this process. We also critically review the data that are in favor or against the involvement of apoptosis in disease generation. We argue that apoptosis is probably not the sole driver of cystogenesis but that a cooperative action of cell death, compensatory cell proliferation and perturbed autophagy gradually establish the disease. Finally, we propose novel strategies for uncovering the mode of action of PC1 and PC2 and suggest means by which their dysfunction or loss of expression lead to cystogenesis and ADPKD development.
Seasonality of sporadic physical processes driving temperature and nutrient high-frequency variability in the coastal ocean off southeast Australia
Publisher: American Geophysical Union (AGU)
Date: 2014
DOI: 10.1002/2013JC009284
TNFα sensitizes hepatocytes to FasL-induced apoptosis by NFκB-mediated Fas upregulation
Publisher: Springer Science and Business Media LLC
Date: 05-09-2018
DOI: 10.1038/S41419-018-0935-9
Abstract: Although it is well established that TNFα contributes to hepatitis, liver failure and associated hepatocarcinogenesis via the regulation of inflammation, its pro-apoptotic role in the liver has remained enigmatic. On its own, TNFα is unable to trigger apoptosis. However, when combined with the transcriptional inhibitor GaLN, it can cause hepatocyte apoptosis and liver failure in mice. Moreover, along with others, we have shown that TNFα is capable of sensitizing cells to FasL- or drug-induced cell death via c-Jun N-terminal kinase (JNK) activation and phosphorylation/activation of the BH3-only protein Bim. In this context, TNFα could exacerbate hepatocyte cell death during simultaneous inflammatory and T-cell-mediated immune responses in the liver. Here we show that TNFα sensitizes primary hepatocytes, established hepatocyte cell lines and mouse embryo fibroblasts to FasL-induced apoptosis by the transcriptional induction and higher surface expression of Fas via the NFκB pathway. Genetic deletion, diminished expression or dominant-negative inhibition of the NFκB subunit p65 resulted in lower Fas expression and inhibited TNFα-induced Fas upregulation and sensitization to FasL-induced cell death. By hydrodynamic injection of p65 shRNA into the tail vein of mice, we confirm that Fas upregulation by TNFα is also NFκB-mediated in the liver. In conclusion, TNFα sensitization of FasL-induced apoptosis in the liver proceeds via two parallel signaling pathways, activation of JNK and Bim phosphorylation and NFκB-mediated Fas upregulation.
Seasonal variability in the continental shelf waters off southeastern Australia: Fact or fiction?
Publisher: Elsevier BV
Date: 2016
Assessing the Use of Area- and Time-Averaging Based on Known De-correlation Scales to Provide Satellite Derived Sea Surface Temperatures in Coastal Areas
Publisher: Frontiers Media SA
Date: 06-08-2018
A high-resolution biogeochemical model (ROMS 3.4 + bio_Fennel) of the East Australian Current system
Publisher: Copernicus GmbH
Date: 25-01-2019
Abstract: Abstract. Understanding phytoplankton dynamics is critical across a range of topics, spanning from fishery management to climate change mitigation. It is particularly interesting in the East Australian Current (EAC) system, as the region's eddy field strongly conditions nutrient availability and therefore phytoplankton growth. Numerical models provide unparalleled insight into these biogeochemical dynamics. Yet, to date, modelling efforts off southeastern Australia have either targeted case studies (small spatial and temporal scales) or encompassed the whole EAC system but focused on climate change effects at the mesoscale (with a spatial resolution of 1/10∘). Here we couple a model of the pelagic nitrogen cycle (bio_Fennel) to a 10-year high-resolution (2.5–5 km horizontal) three-dimensional ocean model (ROMS) to resolve both regional and finer-scale biogeochemical processes occurring in the EAC system. We use several statistical metrics to compare the simulated surface chlorophyll to an ocean colour dataset (Copernicus-GlobColour) for the 2003–2011 period and show that the model can reproduce the observed phytoplankton surface patterns with a domain-wide RMSE of approximately 0.2 mg Chl a m−3 and a correlation coefficient of 0.76. This coupled configuration will provide a much-needed framework to examine phytoplankton variability in the EAC system providing insight into important ecosystem dynamics such as regional nutrient supply mechanisms and biogeochemical cycling occurring in EAC eddies.
PhD Student representation - Bridging the gap between science, service and politics
Publisher: JOSHA, GmbH
Date: 2017
Characterizing the Variability of Boundary Currents and Ocean Heat Content Around New Zealand Using a Multi‐Decadal High‐Resolution Regional Ocean Model
Publisher: American Geophysical Union (AGU)
Date: 04-2023
DOI: 10.1029/2022JC018624
Abstract: New Zealand is located in the southwest Pacific Ocean and is surrounded by a complex system of boundary currents that vary on a variety of time scales, with important impacts on weather, primary productivity, and fisheries. While various observational and modeling studies have shed light on many of the characteristics of New Zealand's ocean circulation, this study provides a comprehensive, quantitative, seamless, 3‐dimensional characterization of the region's boundary current circulation and ocean heat content. We use a 28 yr long hydrodynamic model simulation that accurately represents the mean and variability of the ocean circulation to characterize and quantify the temporal and spatial variability across the region. We show that low‐frequency variability in boundary current transport and upper ocean heat content are correlated over the entire New Zealand oceanic region. Oceanic eddies dominate heat content variability at intra‐annual scales in the northeast of the region, while on the west and southeast coasts heat content varies predominantly at interannual scales controlled by large‐scale changes in the subtropical and sub‐Antarctic fronts. The model shows a significant downstream strengthening and deepening of the boundary currents off northeast New Zealand which, if confirmed by observations, could suggest a significant new understanding of this Western Boundary Current system. This study presents a region‐wide characterization of the temporal and spatial variability of ocean currents and heat content, and their interconnections, providing a vital basis for understanding climate change impacts and the increasing occurrence of marine heatwaves.
Modelling coastal connectivity in a Western Boundary Current: Seasonal and inter-annual variability
Publisher: Elsevier BV
Date: 03-2011
Contrasting phytoplankton composition and primary productivity in multiple mesoscale eddies along the East Australian coast
Publisher: Elsevier BV
Date: 03-2023
Formation and maintenance of high-nitrate, low pH layers in the eastern Indian Ocean and the role of nitrogen fixation
Publisher: Copernicus GmbH
Date: 28-08-2013
Abstract: Abstract. We investigated the biogeochemistry of low dissolved oxygen high-nitrate (LDOHN) layers forming against the backdrop of several interleaving regional water masses in the eastern Indian Ocean, off northwest Australia adjacent to Ningaloo Reef. These water masses, including the forming Leeuwin Current, have been shown directly to impact the ecological function of Ningaloo Reef and other iconic coastal habitats downstream. Our results indicate that LDOHN layers are formed from multiple subduction events of the Eastern Gyral Current beneath the Leeuwin Current (LC) the LC originates from both the Indonesian Throughflow and tropical Indian Ocean. Density differences of up to 0.025 kg m−3 between the Eastern Gyral Current and the Leeuwin Current produce sharp gradients that can trap high concentrations of particles (measured as low transmission) along the density interfaces. The oxidation of the trapped particulate matter results in local depletion of dissolved oxygen and regeneration of dissolved nitrate (nitrification). We document an associated increase in total dissolved carbon dioxide, which lowers the seawater pH by 0.04 units. Based on isotopic measurements (δ15N and δ18O) of dissolved nitrate, we determine that ~ 40–100% of the nitrate found in LDOHN layers is likely to originate from nitrogen fixation, and that, regionally, the importance of N-fixation in contributing to LDOHN layers is likely to be highest at the surface and offshore.
A tale of two eddies: The biophysical characteristics of two contrasting cyclonic eddies in the East Australian Current System
Publisher: American Geophysical Union (AGU)
Date: 03-2017
DOI: 10.1002/2016JC012241
Predicting the submesoscale circulation inshore of the East Australian Current
Publisher: Elsevier BV
Date: 04-2020
An assessment of the East Australian Current as a renewable energy resource
Publisher: Elsevier BV
Date: 04-2020
Retention and Leakage of Water by Mesoscale Eddies in the East Australian Current System
Publisher: American Geophysical Union (AGU)
Date: 04-2019
DOI: 10.1029/2018JC014482
Transport and retention in an upwelling region: The role of across-shelf structure
Publisher: Elsevier BV
Date: 12-2006
Combined mechanistic modelling predicts changes in species distribution and increased co‐occurrence of a tropical urchin herbivore and a habitat‐forming temperate kelp
Publisher: Wiley
Date: 13-06-2020
DOI: 10.1111/DDI.13073
Cyclonic entrainment of preconditioned shelf waters into a frontal eddy
Publisher: American Geophysical Union (AGU)
Date: 02-2015
DOI: 10.1002/2014JC010301
Kick‐off symposium series to help New Ph.D.s is a success
Publisher: American Geophysical Union (AGU)
Date: 05-11-2002
DOI: 10.1029/2002EO000356
Variability and drivers of ocean temperature extremes in a warming Western Boundary Current
Publisher: American Meteorological Society
Date: 02-2021
Abstract: Western boundary current (WBC) extensions such as the East Australian Current (EAC) southern extension are warming 2–3 times faster than the global average. However, there are nuances in the spatial and temporal variability of the warming that are not well resolved in climate models. In addition, the physical drivers of ocean heat content (OHC) extremes are not well understood. Here, using a high-resolution ocean model run for multiple decades, we show nonuniform warming trends in OHC in the EAC, with strong positive trends in the southern extension region (∼36°–38°S) but negative OHC trends equatorward of 33°S. The OHC variability in the EAC is associated with the formation of anticyclonic eddies, which is modulated by transport ∼880 km upstream (EAC mode) and the westward propagation of Rossby waves (eddy mode). Diagnosing the drivers of temperature extremes has implications for predictability both in the EAC and in WBCs more broadly, where ocean warming is already having considerable ecological impacts.
Anticipating changes to future connectivity within a network of marine protected areas
Publisher: Wiley
Date: 28-02-2017
DOI: 10.1111/GCB.13634
Spill-over from aquaculture may provide a larval subsidy for the restoration of mussel reefs
Publisher: Inter-Research Science Center
Date: 18-06-2020
DOI: 10.3354/AEI00363
Abstract: Worldwide bivalve aquaculture is expanding rapidly. Simultaneously, there has been a loss of natural bivalve reefs due to anthropogenic activities. As bivalve reefs support several ecosystem functions disproportionate to the area they cover, there is interest in their restoration. The Firth of Thames (FoT) in northern New Zealand once supported dense populations of green lipped mussels Perna canaliculus , which were extirpated by a dredge fishery in the mid-20 th century. Efforts to restore these biogenic habitats are underway. The largest standing populations of this species in the area currently exist in aquaculture. This study aimed to determine if larval spill-over from aquaculture can provide a larval subsidy to bivalve reef restoration efforts in the FoT. We used a combination of trace elemental fingerprinting and biophysical modelling techniques to determine patterns of larval dispersal in the area. Results of both approaches indicated that the larval pool in the area is well mixed with larvae produced at aquaculture locations capable of settling throughout the study area. Overall this shows, for the first time, that larval spill-over from aquaculture may provide a subsidy to restoration efforts and assist with establishing sustainable populations. When determining restoration locations, the potential for aquaculture populations to act as a larval source should be explicitly considered. Conversely, when considering the location of new aquaculture sites, the consequences of larval spill-over to surrounding wild populations should be assessed. We recommend that restoration efforts and aquaculture be carefully integrated in a network approach which could provide both ecological and economic benefits.
The Marine Virtual Laboratory (version 2.1): enabling efficient ocean model configuration
Publisher: Copernicus GmbH
Date: 19-09-2016
Abstract: Abstract. The technical steps involved in configuring a regional ocean model are analogous for all community models. All require the generation of a model grid, preparation and interpolation of topography, initial conditions, and forcing fields. Each task in configuring a regional ocean model is straightforward – but the process of downloading and reformatting data can be time-consuming. For an experienced modeller, the configuration of a new model domain can take as little as a few hours – but for an inexperienced modeller, it can take much longer. In pursuit of technical efficiency, the Australian ocean modelling community has developed the Web-based MARine Virtual Laboratory (WebMARVL). WebMARVL allows a user to quickly and easily configure an ocean general circulation or wave model through a simple interface, reducing the time to configure a regional model to a few minutes. Through WebMARVL, a user is prompted to define the basic options needed for a model configuration, including the model, run duration, spatial extent, and input data. Once all aspects of the configuration are selected, a series of data extraction, reprocessing, and repackaging services are run, and a “take-away bundle” is prepared for download. Building on the capabilities developed under Australia's Integrated Marine Observing System, WebMARVL also extracts all of the available observations for the chosen time–space domain. The user is able to download the take-away bundle and use it to run the model of his or her choice. Models supported by WebMARVL include three community ocean general circulation models and two community wave models. The model configuration from the take-away bundle is intended to be a starting point for scientific research. The user may subsequently refine the details of the model set-up to improve the model performance for the given application. In this study, WebMARVL is described along with a series of results from test cases comparing WebMARVL-configured models to observations and manually configured models. It is shown that the automatically configured model configurations produce a good starting point for scientific research.
Observing system simulation experiments reveal that subsurface temperature observations improve estimates of circulation and heat content in a dynamic western boundary current
Publisher: Copernicus GmbH
Date: 31-08-2022
Abstract: Abstract. Western boundary currents (WBCs) form the narrow, fast-flowing poleward return flows of the great subtropical ocean gyres and are sources of rapidly varying mesoscale eddies. Accurate simulation of the vertical structure, separation latitude, and ocean heat content of WBCs is important for understanding the poleward transport of heat in the global ocean. However, state estimation and forecasting in WBC regions, such as the East Australian Current (EAC), the WBC of the South Pacific subtropical gyre, is challenging due to their dynamic nature and lack of observations at depth. Here we use observing system simulation experiments to show that subsurface temperature observations in a high eddy kinetic energy region yield large improvement in representation of key EAC circulation features, both downstream and ∼ 600 km upstream of the observing location. These subsurface temperature observations (in concert with sea surface temperature and height measurements) are also critical for correctly representing ocean heat content along the length of the EAC. Furthermore, we find that a more poleward separation latitude leads to an EAC and eddy field that is represented with far reduced error, compared to when the EAC separates closer to the Equator. Our results demonstrate the importance of subsurface observations for accurate state estimation of the EAC and ocean heat content that can lead to marine heatwaves. These results provide useful suggestions for observing system design under different oceanographic regimes, for ex le, adaptive s ling to target high energy states with more observations and low energy states with fewer observations.
The physics of New Zealand’s shelf seas: introduction to the special issue
Publisher: Informa UK Limited
Date: 02-01-2021
Multiple spawning events promote increased larval dispersal of a predatory fish in a western boundary current
Publisher: Wiley
Date: 28-04-2020
DOI: 10.1111/FOG.12473
Development and evaluation of a high-resolution reanalysis of the East Australian Current region using the Regional Ocean Modelling System (ROMS 3.4) and Incremental Strong-Constraint 4-Dimensional Variational (IS4D-Var) data assimilation
Publisher: Copernicus GmbH
Date: 26-10-2016
Abstract: Abstract. As with other Western Boundary Currents globally, the East Australian Current (EAC) is highly variable making it a challenge to model and predict. For the EAC region, we combine a high-resolution state-of-the-art numerical ocean model with a variety of traditional and newly available observations using an advanced variational data assimilation scheme. The numerical model is configured using the Regional Ocean Modelling System (ROMS 3.4) and takes boundary forcing from the BlueLink ReANalysis (BRAN3). For the data assimilation, we use an Incremental Strong-Constraint 4-Dimensional Variational (IS4D-Var) scheme, which uses the model dynamics to perturb the initial conditions, atmospheric forcing, and boundary conditions, such that the modelled ocean state better fits and is in balance with the observations. This paper describes the data assimilative model configuration that achieves a significant reduction of the difference between the modelled solution and the observations to give a dynamically consistent “best estimate” of the ocean state over a 2-year period. The reanalysis is shown to represent both assimilated and non-assimilated observations well. It achieves mean spatially averaged root mean squared (rms) residuals with the observations of 7.6 cm for sea surface height (SSH) and 0.4 °C for sea surface temperature (SST) over the assimilation period. The time-mean rms residual for subsurface temperature measured by Argo floats is a maximum of 0.9 °C between water depths of 100 and 300 m and smaller throughout the rest of the water column. Velocities at several offshore and continental shelf moorings are well represented in the reanalysis with complex correlations between 0.8 and 1 for all observations in the upper 500 m. Surface radial velocities from a high-frequency radar array are assimilated and the reanalysis provides surface velocity estimates with complex correlations with observed velocities of 0.8–1 across the radar footprint. A comparison with independent (non-assimilated) shipboard conductivity temperature depth (CTD) cast observations shows a marked improvement in the representation of the subsurface ocean in the reanalysis, with the rms residual in potential density reduced to about half of the residual with the free-running model in the upper eddy-influenced part of the water column. This shows that information is successfully propagated from observed variables to unobserved regions as the assimilation system uses the model dynamics to adjust the model state estimate. This is the first study to generate a reanalysis of the region at such a high resolution, making use of an unprecedented observational data set and using an assimilation method that uses the time-evolving model physics to adjust the model in a dynamically consistent way. As such, the reanalysis potentially represents a marked improvement in our ability to capture important circulation dynamics in the EAC. The reanalysis is being used to study EAC dynamics, observation impact in state-estimation, and as forcing for a variety of downscaling studies.
Nitrate Sources, Supply, and Phytoplankton Growth in the Great Australian Bight: An Eulerian-Lagrangian Modeling Approach
Publisher: American Geophysical Union (AGU)
Date: 02-2018
DOI: 10.1002/2017JC013542
On the East Australian Current: Variability, encroachment, and upwelling
Publisher: American Geophysical Union (AGU)
Date: 07-2004
DOI: 10.1029/2003JC001833
Correction: Mesoscale circulation determines broad spatio-temporal settlement patterns of lobster
Publisher: Public Library of Science (PLoS)
Date: 02-04-2019
The Global Ocean Observing System
Publisher: GODAE OceanView
Date: 11-08-2018
Coastal seascape variability in the intensifying East Australian Current Southern Extension
Publisher: Frontiers Media SA
Date: 21-09-2022
DOI: 10.3389/FMARS.2022.925123
Abstract: Coastal pelagic ecosystems are highly variable in space and time, with environmental conditions and the distribution of biomass being driven by complex processes operating at multiple scales. The emergent properties of these processes and their interactive effects result in complex and dynamic environmental mosaics referred to as “seascapes”. Mechanisms that link large-scale oceanographic processes and ecological variability in coastal environments remain poorly understood, despite their importance for predicting how ecosystems will respond to climate change. Here we assessed seascape variability along the path of the rapidly intensifying East Australian Current (EAC) Southern Extension in southeast Australia, a hotspot of ocean warming and ecosystem tropicalisation. Using satellite and in situ measures of temperature, salinity and current velocity coupled with contemporaneous measurements of pelagic biomass distribution from nine boat-based active acoustic surveys in five consecutive years, we investigated relationships between the physical environment and the distribution of pelagic biomass (zooplankton and fish) at multiple timescales. Survey periods were characterised by high variability in oceanographic conditions, with variation in coastal conditions influenced by meso-to-large scale processes occurring offshore, including the position and strength of eddies. Intra-annual variability was often of a similar or greater magnitude to inter-annual variability, suggesting highly dynamic conditions with important variation occurring at scales of days to weeks. Two seascape categories were identified being characterised by (A) warmer, less saline water and (B) cooler, more saline water, with the former indicating greater influence of the EAC on coastal processes. Warmer waters were also associated with fewer, deeper and less dense biological aggregations. As the EAC continues to warm and penetrate further south, it is likely that this will have substantial effects on biological activity in coastal pelagic ecosystems, including a potential reduction in the accessibility of prey aggregations to surface-feeding predators and to fisheries. These results highlight the import role of offshore oceanographic processes in driving coastal seascape variability and biological activity in a region undergoing rapid oceanic warming and ecological change.
Shelf and Coastal Ocean Observing and Modeling Systems: A New Frontier in Operational Oceanography
Publisher: GODAE OceanView
Date: 11-08-2018
Related Organisations
Related Funding Activities
Discovery Projects - Grant ID: DP230100505
Start Date: 07-2023
End Date: 06-2026
Amount: $693,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP140102337
Start Date: 2014
End Date: 07-2017
Amount: $180,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP170100498
Start Date: 09-2018
End Date: 04-2022
Amount: $440,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP1093510
Start Date: 02-2010
End Date: 12-2013
Amount: $503,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP120100592
Start Date: 06-2012
End Date: 12-2016
Amount: $513,617.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP220100515
Start Date: 2023
End Date: 12-2025
Amount: $389,674.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP150100064
Start Date: 03-2016
End Date: 02-2019
Amount: $310,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP160100162
Start Date: 12-2016
End Date: 09-2022
Amount: $213,445.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP210200689
Start Date: 10-2022
End Date: 10-2025
Amount: $441,371.00
Funder: Australian Research Council
View Funded Activity