ORCID Profile
0000-0002-6049-8600
Current Organisation
University of Western Australia
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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.
Physical Oceanography | Geophysical Fluid Dynamics | Oceanography | Photogrammetry and Remote Sensing | Geophysics | Computational Fluid Dynamics
Expanding Knowledge in the Earth Sciences | Physical and Chemical Conditions of Water in Marine Environments | Marine Oceanic Processes (excl. climate related) | Natural Hazards in Marine Environments | Climate Change Models |
Publisher: American Physical Society
Date: 19-11-2017
Publisher: Elsevier BV
Date: 05-2015
Publisher: Springer Science and Business Media LLC
Date: 19-10-2017
Publisher: American Geophysical Union (AGU)
Date: 26-01-2011
DOI: 10.1029/2009JC005881
Publisher: Wiley
Date: 26-10-2018
DOI: 10.1002/LNO.11051
Publisher: Elsevier BV
Date: 10-2015
Publisher: American Meteorological Society
Date: 07-2019
DOI: 10.1175/JTECH-D-18-0200.1
Abstract: We present a statistical method for reconstructing continuous background density profiles that embeds incomplete measurements and a physically intuitive density stratification model within a Bayesian hierarchal framework. A double hyperbolic tangent function is used as a parametric density stratification model that captures various pycnocline structures in the upper ocean and offers insight into several density profile characteristics (e.g., pycnocline depth). The posterior distribution is used to quantify uncertainty and is estimated using recent advances in Markov chain Monte Carlo s ling. Temporally evolving posterior distributions of density profile characteristics, isopycnal heights, and nonlinear ocean process models for internal gravity waves are presented as ex les of how uncertainty propagates through models dependent on the density stratification. The results show 0.95 posterior interval widths that ranged from 2.5% to 4% of the expected values for the linear internal wave phase speed and 15%–40% for the nonlinear internal wave steepening parameter. The data, collected over a year from a through-the-column mooring, and code, implemented in the software package Stan, accompany the article.
Publisher: American Geophysical Union (AGU)
Date: 04-2016
DOI: 10.1002/2015JC011181
Publisher: American Geophysical Union (AGU)
Date: 08-2018
DOI: 10.1029/2018JC013939
Publisher: Wiley
Date: 20-11-2020
Publisher: American Geophysical Union (AGU)
Date: 06-2023
DOI: 10.1029/2022MS003500
Abstract: We describe a framework for the simultaneous estimation of model parameters in a partial differential equation using sparse observations. Markov Chain Monte Carlo s ling is used in a Bayesian framework to estimate posterior probability distributions for each parameter. We describe the necessary components of this approach and its broad potential for application in models of unsteady processes. The framework is applied to three case studies, of increasing complexity, from the field of cohesive sediment transport. We demonstrate that the framework can be used to recover posterior distributions for all parameters of interest and the results agree well with independent estimates (where available). We also demonstrate how the framework can be used to compare different model parameterizations and provide information on the covariance between model parameters.
Publisher: Wiley
Date: 05-10-2021
DOI: 10.1002/LNO.11939
Abstract: A field experiment study of flow transport around a coral reef was conducted at Scott Reef, an offshore atoll in the Timor Sea. A drifter deployment was designed based on the insight derived from two Lagrangian data analysis approaches, the finite‐time Lyapunov exponent method and the optimized‐parameter spectral clustering method, which were used to analyze the predictions of a numerical model. This analysis predicted the formation of a key transport barrier during a critical time of the tidal cycle that separated two bodies of water, one remaining trapped within the lagoon, and one advected offshore this transport structure had no clear signature upon inspection of the velocity fields and thus the use of Lagrangian methods was crucial. The observed drifter trajectories confirmed the predictions, with the drifters separating into two clusters, one on each side of the transport barrier. The results demonstrate how Lagrangian approaches elucidate the processes governing connectivity and water exchanges between atolls and the surrounding ocean.
Publisher: American Geophysical Union (AGU)
Date: 12-2015
DOI: 10.1002/2015JC010868
Publisher: American Physical Society (APS)
Date: 17-10-2018
Publisher: American Meteorological Society
Date: 11-2017
Abstract: An estuary is classified as unsteady when the salinity adjustment time is longer than the forcing time scale. Predicting salt content or salt intrusion length using scaling arguments based on a steady-state relationship between flow and salinity is inaccurate in these systems. In this study, a time-dependent salinity box model based on an unsteady Knudsen balance is used to demonstrate the effects of river flow, inward total exchange flow (tidal plus steady), and the salinity difference between inflow and outflow on the salt balance. A key component of the box model is a relationship that links the normalized difference between inflowing and outflowing salinity at the mouth and the mean salinity content. The normalized salinity difference is shown to be proportional to the mean salinity squared, based on theoretical arguments from the literature. The box model is validated by hindcasting 5 years of mean salinity in Galveston Bay (estimated from coarse observations) in response to highly variable river discharge. It is shown that this estuary typically has a long adjustment time relative to the forcing time scales, and, therefore, the volume-averaged salinity rarely reaches equilibrium. The box model highlights the reasons why the adjustment time in a large, partially mixed estuary like Galveston Bay is slower when the mean salt content is higher. Furthermore, it elucidates why the salt content in the estuary is more responsive to changes in river flow than in landward exchange flow at the estuary mouth, even though the latter quantity is usually several times larger.
Publisher: American Geophysical Union (AGU)
Date: 25-09-2020
DOI: 10.1029/2020GL089591
Publisher: Wiley
Date: 26-05-2021
Publisher: American Geophysical Union (AGU)
Date: 12-2021
DOI: 10.1029/2021JC017538
Abstract: While it has been recognized for some time that large litude non‐linear internal waves (NLIW) can mobilize and transport sediment, quantitative observations of this process are rare. Rarer still are accompanying estimates of suspended sediment mass concentration (SSC) during the passage of NLIW. Here, we present high resolution observations of NLIW and the SSC response within the bottom boundary layer. The observations were made in 250 m of water in a mildly sloping region of the Browse Basin on Australia’s Northwest Shelf. We compare two independent but direct calibration methods, and employ Bayesian methods to estimate the uncertainty in SSC. During a large NLIW event, the peak mean SSC estimate at 0.49 m above the sea bed was 161 mg L −1 , with a maximum time‐rate‐of‐change of 0.14 mg L −1 s −1 . The unsteady boundary layer forcing under NLIW resulted in a variable time‐height dependent relationship between bed stress and SSC with increasing height above the sea bed. Suspended sediment was restricted to the bottom mixing layer, with sharp vertical gradients of up to 40 mg L −1 m −1 observed at the edge of the layer. The observations presented here are intended to offer guidance to numerical sediment modelers about likely SSC under strong NLIW.
Publisher: American Society of Civil Engineers
Date: 27-09-2010
DOI: 10.1061/41121(388)33
Publisher: American Meteorological Society
Date: 2019
Abstract: Large- litude mode-2 nonlinear internal waves were observed in 250-m-deep water on the Australian North West shelf. Wave litudes were derived from temperature measurements using three through-the-water-column moorings spaced 600 m apart in a triangular configuration. The moorings were deployed for 2 months during the transition period between the tropical monsoon and the dry season. The site had a 25–30-m- litude mode-1 internal tide that essentially followed the spring–neap tidal cycle. Regular mode-2 nonlinear wave trains with litudes exceeding 25 m, with the largest event exceeding 50 m, were also observed at the site. Overturning was observed during several mode-2 events, and the relatively high wave Froude number and steepness (0.15) suggested kinematic (convective) instability was likely to be the driving mechanism. The presence of the mode-2 waves was not correlated with the tidal forcing but rather occurred when the nonlinear steepening length scale was smaller than the distance from the generation region to the observation site. This steepening length scale is inversely proportional to the nonlinear parameter in the Korteweg–de Vries equation, and it varied by at least one order of magnitude under the evolving background thermal stratification over the observation period. Despite the complexity of the internal waves in the region, the nonlinear steepening length was shown to be a reliable indicator for the formation of large- litude mode-2 waves and the rarer occurrence of mode-1 large- litude waves. A local mode-2 generation mechanism caused by a beam interacting with a pycnocline is demonstrated using a fully nonlinear numerical solution.
Publisher: American Geophysical Union (AGU)
Date: 2022
DOI: 10.1029/2020JC017055
Abstract: We present 15 days of both mean and turbulent field observations bottom mixing‐layer at a gently sloping 250 m deep continental shelf site, energized by tides and nonlinear internal waves (NLIWs). The tidal frequency forcing was due to the combined effects of the barotropic tide and a mode‐1 internal tide (IT), while the NLIWs were predominantly mode‐1 waves of depression. The bottom mixing‐layer thickness varied at both semidiurnal and sub‐tidal ∼O(10)d frequencies, with an average thickness of around 10 m. Compression and expansion of the mixing‐layer by both the IT and NLIWs affected the mean velocity profiles in the mixing‐layer, while the phasing between the barotropic and baroclinic flows led to an asymmetry in mean velocity profiles between periods of rising and falling isotherms. With the exception of periods of flow reversal, the turbulent kinetic energy balance and turbulent stress observations were consistent with the existence of an inertial‐sublayer with thickness of approximately 10%–15% of the mixing‐layer thickness ( ∼1 m), even beneath NLIWs. In the outer portion of the mixing‐layer—that is, above the inertial‐sublayer—NLIWs modulated the local turbulence spectra. We discuss the observations in the context of a predictive model for mixing‐layer thickness. The analysis suggests that the high‐frequency variability in mixing‐layer thickness was dominated by internal wave pumping, though strength of the ambient stratification and the frequency of the forcing were important controls on the time‐averaged (sub‐tidal) variation.
Publisher: Elsevier BV
Date: 03-2022
Publisher: American Geophysical Union (AGU)
Date: 10-2021
DOI: 10.1029/2021JC017570
Abstract: We present an empirical model of the seasonal variability of the internal tide using seasonal harmonics to modulate the litude of the fundamental tidal constituents. Internal tide data, from both long‐term, in‐situ moorings and a mesoscale‐resolving and internal tide‐resolving ocean model, are used to demonstrate the performance of the seasonal harmonic model for the Indo‐Australian Basin region. The seasonal model describes up to 15% more of the observed (baroclinic) sea surface height variance than a fixed‐ litude harmonic model at the mooring sites. The ocean model results demonstrate that the study region, which includes the Australian North West Shelf (NWS), Timor Sea, and southern Indonesian Islands, is dominated by standing wave interference patterns due to the presence of multiple generation sites. The seasonal harmonic model reveals that temporal shifts in the standing wave patterns coincide with seasonal variations in density stratification. This shift is particularly evident within distances of 2–3 internal wave lengths from strong generation sites. The fraction of the variance of the internal tide signal explained by seasonal modulations is largest in standing wave node regions, contributing to differences in predictive skill of the seasonal harmonic model at two moorings separated by only 38 km. Output of the harmonic model also demonstrates that the seasonally evolving internal tide propagating southward from Lombok Strait had a small litude in October when shear from the Indonesian Throughflow was strongest.
Publisher: American Geophysical Union (AGU)
Date: 06-2012
DOI: 10.1029/2011JC007523
Publisher: Wiley
Date: 16-11-2022
Publisher: Elsevier BV
Date: 06-2021
Publisher: American Meteorological Society
Date: 06-2019
Abstract: Internal tide generation at sloping topography is nominally determined by the local slope geometry, density stratification, and tidal forcing. Recent global ocean models have revealed that remotely generated internal tides (RITs) can also influence locally generated internal tides (LITs). Field measurements with through-the-water column moorings on the southern portion of the Australian North West Shelf (NWS) suggested that RITs led to local regions with either positive or negative barotropic to baroclinic energy conversion. Three-dimensional numerical simulations were used to examine the role of RITs on local internal tide climatology on the inner slope and shelf portion of the NWS. The model demonstrated the principle remote generation site was the western portion of the offshore Exmouth Plateau. Extending the model domain to include this offshore plateau region increased the local net energy conversion on the inner shelf by 13.5% and on the slope by 8%. Simulations using an idealized 2D model configuration aligned along the principal direction of RIT propagation demonstrated that the sign and magnitude of the local energy conversion was dependent on the distance between the remote and local generation sites, the phase difference between the local barotropic tide and the RIT, and the litude of both the local barotropic tide and the RIT. For RITs with a low-wave Froude number (Fr 0.05), where Fr is the ratio of the internal wave baroclinic velocity to the linear wave speed, the conversion rates were consistent with kinematic predictions based on the phase difference only. For stronger flows with Fr 0.05, the conversion rates showed a nonlinear dependence on Fr.
Publisher: Elsevier BV
Date: 11-2019
Publisher: Elsevier BV
Date: 02-2018
Start Date: 2018
End Date: 12-2022
Amount: $387,152.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 12-2023
Amount: $772,031.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2022
End Date: 04-2026
Amount: $707,971.00
Funder: Australian Research Council
View Funded Activity