Sustained monitoring of the EAC: mass, heat and freshwater transports

Voyage Number

IN2021_V03

Voyage Dates

07 May, 2021 to 03 Jun, 2021

Voyage Location

Hobart to Brisbane

Chief Scientist

Dr Chris Chapman

Institution

IMOS

View the full voyage

Research voyage to the East Australian Current (EAC) off Brisbane to maintain a long-term deep-water mooring array for monitoring of ocean and climate.

The long-term ocean monitoring by the EAC deep-water mooring array, a component of the Integrated Marine Observing System (IMOS), is central to our understanding of the relationship between global ocean and climate variability. The EAC is the complex and highly energetic western boundary current of the South Pacific Ocean.  It is the dominant mechanism for the redistribution of heat and freshwater between the ocean and atmosphere in the Australian region.  

The primary voyage objective is to recover and re-deploy six deep-water moorings in waters off Brisbane from the continental shelf (500 m depth) to abyssal waters (5000 m depth).

There are four other projects included on this voyage:

• Dynamics of larval fish diversity for ocean observing off North Stradbroke Island (Prof Iain Suthers, UNSW): Survey of plankton and larval fish to better understand biodiversity and factors influencing productivity in continental shelf waters.
• Argo float deployments (Dr Beatriz Pena-Molino, CSIRO): Up to six core Argo floats will be deployed during the voyage as part of the international Argo program.
• Biogeochemical-Argo float deployments (Dr Peter Strutton, UTAS): Two BGC-Argo floats will be deployed during the voyage as part of the Australian contribution to global Biogeochemical-Argo program.
• Expendable Bathythermographs deployments (Rebecca Cowley, CSIRO): Expendable Bathythermographs (XBT) will be regularly deployed during the transit from Hobart to the mooring sites as part of the Global Temperature and Salinity Profile Programme (GTSPP).

The science team on this voyage will have 29 science participants (and 20 crew) representing six institutions.

COVID-19 Protocols

To safeguard the health and well-being of participants, strict COVID-19 protocols will apply to all activities on this voyage, including testing of all participants for COVID-19 prior to departure.

Voyage outcomes

During this voyage, researchers successfully recovered and deployed six moorings in the EAC between the continental slope and the abyssal plain off the coast from Brisbane. In addition, 12 CTD/LADCP stations were completed, which will support the moorings in effectively tracking variability of the EAC. Transit periods during the voyage were utilised to conduct 65 plankton tows which will be used to assess the ramifications of a changing EAC on coastal ecosystems including as part of the national IMOS-larval fish monitoring program.

The voyage has sustained the long-term monitoring of the EAC and collected data that will improve our understanding of its influences on climate, leading to more reliable forecasts for eastern Australia and coastal communities, and improved management of important coastal fisheries. 

A systematic survey of larval fish, jellyfish and plankton diversity off North Stradbroke Island national reference station (NRS) was also completed during the voyage, along with the deployment of six Argo floats and two BGC-Argo floats as part of the international Argo program.