Research Activities

Research Activities

We are currently engaged in a number of research projects in the coastal oceanographic area, with a geographic focus on the Western Australian region. The main goal is to understand processes, particularly in the scales from regional ocean flows down to small scale turbulent mixing. The project work involves an integration of field observations, of both mean and turbulent flows, and the development and application of numerical ocean circulations models. The work is funded through the Australian Research Council, the Western Australian Government, and via the strong links we have with the offshore oil and gas industry operating on the Australian North West Shelf. Details of some of the projects are below.

Turbulent mixing driven by internal wave breaking over complex topography

 

Transient coastal upwelling along Western Australia

The southward-flowing Leeuwin Current suppresses coastal upwelling along much of the West Australian coast, but during the summer strong southerly winds can drive an inshore surface current system at the outer edge of the World Heritage Area Ningaloo Reef (the ‘Ningaloo Current’).  This, in turn, can generate sporadic, transient upwelling along Ningaloo that moves deep, cool, nutrient-rich water onto the reef, thereby controlling reef productivity and ecology.  This project is using both field measurements, from moorings and ship based transects, and numerical modeling using ROMS to conduct the first detailed physical oceanographic study to quantify this transient upwelling and the associated dynamics controlling the Ningaloo Current system (supported by the Australian Research Council and AIMS).

 

ROMS modelling of transient upwelling at Ningaloo (Xu et al., 2013 )

 

The generation and dissipation of tidally-forced Large Amplitude Internal Waves

The strong tides on the North West Shelf force the strongly density-stratified waters over the shelf/slope bathymetry generated a very strong internal tide often characterized by Large Amplitude Internal Waves (LAIW), often called solitons. Field measurements have been conducted in regions where the LAIW are both generated and dissipated, with particular focus on the turbulence and energetic mixing that can occur in the near-bottom regions. This is particularly important for the design and operation of pipelines and infrastructure for the oil and gas industry and for the controls on vertical mixing and nutrient fluxes over the Shelf. These field observations are being used to develop and apply the fully non-hydrostatic circulation model SUNTANS to predict the intensity and extent of internal wave driven dynamics in the region (supported by the Australian Research Council and Woodside Energy Limited in collaboration with Stanford University).

Deployment of field instrumentation for internal wave study

Extreme tidal forcing of a topographically complex coastal region: the Kimberley, Western Australia

The aim of this project is to conduct the first detailed hydrodynamic study of the regional circulation and mixing processes along the central Kimberley coastal region in the very north of Western Australia. The area is characterised by extensive island archipelagos, a complex series of coastal headlands, and is subject to very large tidal currents driven by the 10 m tides in the region. This study, done in collaboration with the Australian Institute of Marine Science (AIMS), employs a combination of field measurements, laboratory observations and numerical modeling to quantify, for the first time, the influence of the complex topography on circulation, ocean mixing and hence the exchange and flushing of material (e.g., nutrients, contaminants, sediment, larvae etc.) throughout this region (supported by the Australian Research Council and AIMS).

Observed density contours along offshore transect (Lei et al, 2014)

Ship transects in wet season in Kimberley (Lei et al, 2012)

 

Ocean response to Tropical Cyclone (TC) forcing on the Australian North West Shelf

Topical Cyclones (TC) are the dominant physical forcing feature during the summer months on the Australian North West Shelf, home to one of the world’s largest offshore oil and gas industries. This project is using new field observations to develop and apply a numerical ocean model to accurately predict the ocean response to TC forcing. The work will characterise the spatial and temporal ocean response to tropical cyclone forcing not simply at the free surface but throughout the density stratified water column. The outcomes will result in a paradigm shift for the oil and gas industry in their response to the hazards imposed by tropical cyclone forcing (supported by the Australian Research Council and Woodside Energy Limited).

Cyclone Monty off the NW Coast of Australia

 

ROMS modelling of cyclone Monty impact on North West Shelf

Coupled physical and biogeochemical dynamics on the Australian North West Shelf

The project aims to understand the dynamics of ocean transport and mixing processes across the Australian North West Shelf (NWS) and their role in regulating primary productivity. A combination of hydrodynamic and biogeochemical observations are now underway will elucidate the role of transport and mixing processes on the supply of nutrients to the euphotic zone at specific NWS sites. We will develop a coupled physical-biogeochemical numerical model around ROMS that includes a description of the internal dynamics, allowing us to quantify the role of physical processes in controlling nutrient fluxes for the entire NWS. A more focused program is also being conducted at finer resolution over some of the coral reef systems in the region. The model will be used to investigate the sensitivity of ocean mixing and transport, nutrient fluxes and productivity to projected climate variability (supported by the Australian Research Council in collaboration with AIMS and University of Tasmania).

Model results from coupled physical and biogeochemical models of flow over Ningaloo Reef (See Zhang et al., 2011,2013)