How will the key science questions be addressed?

• Are internal waves significant and are they a source of shelf-slope boundary mixing?

The significance of internal waves will be determined for the deep shelf slope sites using the Acoustic Doppler Current Profilers, Conductivity Temperature Depth and temperature loggers data through several short (2-3 days) mooring deployments during summer and with sampling intervals at seconds or less.  The logger and Conductivity Temperature Depth data collected will provide evidence of the extent of bottom mixing.

East Australian Current System

• What is the temporal and spatial variability and nature of the Flinders Current/Leeuwin Current and coastal shelf boundary currents including effects of seasonal and ENSO forcing?

The number of moorings maintained continuously will be increased from two to three.  This will involve one additional deep water mooring on the 200 m isobaths, located between the National Reference Station and inshore of the deep slope mooring.  These moorings will consist of upward looking Acoustic Doppler Current Profilers, Conductivity Temperature Depth and temperature loggers so as to resolve temporal and cross-shelf variability of the currents. Conductivity Temperature Depth loggers on apex predators will compliment mooring data and expand the geographic distribution of observations.  In addition, the data will be supplemented by that from satellites (altimeter and SST) as well as sea glider observations.

• What is the connectivity of the boundary currents to those off W.A and the Tasman Outflow both from a physical viewpoint and from the perspective of the transport of marine biota, pathogens and invasive species?

Connectivity with the boundary currents off Western Australia will be determined using data from both the SA-IMOSand WA-IMOS Nodes.  Two new slope mooring arrays are planned by the Bluewater and Climate Node for the southern tip of Tasmania and Leeuwin Current and will allow the connectivity of the Flinders Current with the Tasman Outflow and Leeuwin Current to be determined.

Antarctic Circumpolar Current

• Is the Antarctic Circumpolar Wave detectable and significant?

Repeated mooring deployments, temperature measurements and Conductivity Temperature Depth loggers on apex predators will, over 8 to 12 years, allow for the detection of the 4 year period Antarctic Circumpolar Wave, 4 to7 year period ENSO events and determination of the impact on the shelf and slope circulation.