Continental Shelf and Coastal Processes

The boundary current systems transfer heat, salt and nutrients onto the continental shelf and into the coastal region.  It is at the interface between the currents and the shelf that the large scale climate patterns such as El Niño/Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and the Southern Annular Mode (SAM) undergo regional modulation through the interaction of the currents, eddies, and local coastal flows.  

Furthermore, the exchanges between the deepwater systems and the shelf are a two-way process, with outflows of freshwater and nutrients also spreading from the shelf to the deep ocean.  Identifying local manifestations of these global phenomena is crucial to understanding the drivers of variability on the continental shelf and their influence on regional marine ecosystems. 

Australia has a large and varied continental shelf and coastal environment; broad and shallow in the tropical north and narrow on the sub-tropical east and west coasts. There are key processes occurring across this environment that provide a focus for observing connections between global ocean processes, boundary currents and biological responses on the continental shelf. These include encroachment of warm and cold-core eddies, upwelling and down-welling systems, coastal currents, and wave climates.

Evidence for a strong connection between conditions on and off the shelf suggests that observations that span both domains are needed to understand variability on the continental shelf.  In the IMOS context, this means close integration between the Bluewater and Climate Node and each of the regional Nodes.

The following high-level science questions will guide the Bluewater and Climate IMOS observing strategy in this area:

Boundary Current/shelf interactions 

  • How does the large-scale circulation (boundary currents, gyres, eddies and interbasin flows) affect the shelf and coastal environment?

Upwelling and Downwelling 

  • How do boundary currents moderate the strength, extent and variability of upwelling and downwelling?

Shelf Currents 

  • How do offshore flows interact with shelf currents?

Wave Processes

  • How does the large-scale circulation and stratification affect the wave environment (e.g. internal waves and coastally trapped waves) on the continental shelf?