The IMOS Argo Australia Facility, which is operated by CSIRO, is a major contributor to the global array of 3,908 floats, maintaining 10% of the international Argo program.
Argo Floats measure temperature, conductivity (for conversion to salinity), and pressure in the upper 2 km of the ocean. By providing continuous observations of the global ocean, Argo floats have revolutionised our understanding of the oceans and their role in climate.
However, regular Argo floats only sample about half the ocean volume. Sparse ship-based measurements show that change is also underway in the deep ocean. Recognising the urgent need for more complete sampling of the deeper part of the ocean, the International Argo community has developed Deep Argo Floats that can reliably measure temperature and salinity to depths of 6 km.
The sustained, continuous measurements provided by Deep Argo Floats will allow changes in the deep ocean to be assessed and understood for the first time. Deep Argo will provide crucial measurements for tracking changes in ocean heat content, salinity, sea level rise, and deep circulation. The deep ocean slows the rate of climate change by taking up heat and carbon, therefore changes in the deep ocean may affect the pace of climate change
The new Deep Argo Floats sub-Facility will enhance Argo Australia by adding deep floats able to profile the full water depth, and contribute to the global array target of 1,200 Deep Argo Floats. Just as Argo has revolutionised oceanography in the upper ocean, Deep Argo will drive a similar revolution in the deep ocean.
“We used to think the deep ocean was very stable and unlikely to change very rapidly. But sparse observations from ships show that this is not the case, with the deep ocean south of Australia changing more rapidly than anywhere else,” said the leader of the new sub-facility and CSIRO scientist, Dr Steve Rintoul.
“By providing sustained, broad-scale measurements of the deep ocean, Deep Argo will help us to understand how and why the deep ocean is changing, and to assess the consequences for climate and sea-level rise.”
IMOS will contribute 15 Deep Argo Floats to the global array, and our partner the Australian Antarctic Program Partnership (AAPP) are also providing a substantial contribution with a further 10 Deep Argo Floats.
The locations of float deployments will be determined in consultation with scientists by considering scientific justification, availability of supporting measurements, co-investment, and feasibility.