Biogeochemical Argo

What is Biogeochemical Argo?

Biogeochemical Argo floats are profiling floats that, in addition to temperature and salinity, carry sensors to measure any combination of dissolved oxygen, pH, dissolved nitrate, chlorophyll fluorescence, particulate backscatter and incoming solar radiation. These measurements are used to address science questions regarding variability in the oceans’ biological carbon pump, the uptake of anthropogenic CO2 by the ocean, deoxygenation and acidification, marine resource management and validation of satellite observations.

The IMOS Biogeochemical Argo sub-facility will deploy Biogeochemical Argo floats in scientifically important areas of Australia’s Exclusive Economic Zone, surrounding seas and the Southern Ocean.

The data will provide a continuously growing time series of essential ocean variables for marine and coastal environments, and help with understanding the impact of changes in the physical environment on biogeochemical cycles and ecosystems.

The global Biogeochemical Argo array will drive a transformative shift in our ability to observe and predict the effects of climate change on ocean metabolism, carbon uptake and marine ecosystems.

The initial IMOS investment in the Biogeochemical Argo sub-facility is A$2M over three years. This will fund the development and operation of the data systems, and with co-investment, around 12 Biogeochemical Argo float deployments. The data system for the Biogeochemical Argo sub-facility will be scalable to handle of the order of 25 float deployments per year, or 100 active floats, equivalent to 10% of the global Biogeochemical Argo network. This is the goal of the Biogeochemical Argo sub-facility, consistent with Australia’s current contribution to the global core Argo array.

In collaboration with the US SOCCOM project, the first IMOS Australia Biogeochemical Argo floats will be deployed in the East Australia Current in September 2019.

 

Key Data Streams

BGC-Argo float capabilities have been demonstrated through pilot projects in many ocean basins over the past decade. This activity has been united via the creation of the International Biogeochemical-Argo (iBGC) project which displays the status of the current float array, collates publication outputs, coordinates best practice approaches to deployment and quality control and assessment, and promotes development of a sustained global array.

In 2016 the international BGC-Argo project issued an Implementation Plan for a global array. Based on model simulations and correlation length scale assessments, in particular for the applications of constraining ocean CO2 uptake and determining chlorophyll fields, the plan suggested the following array parameters:

  1. A repeat frequency of 5-7 days to address timescales of ocean biomass changes

  2. Profiles to at least 1000 m to allow deep ocean climatology to serve as a reference (with a preference for 2000m to match core Argo protocols)

  3. A constellation of at least 5, preferably 6 sensors as shown listed above, to:

    • Allow improved validation by comparing sensors

    • Provide measurement redundancy for key biogeochemical processes

    • Address a broad range of applications

The Implementation Plan recognized that many important science advances have been and will continue to be achieved with different sensor configurations and different missions, that other sensors have merit, and that new sensors will continue to become available. But these needs and improvements must be balanced against assessment of what is achievable and affordable. Choosing optimal approaches to addressing these issues remains an important part of developing momentum towards a global BGC-Argo array. Inclusion of BGC-Argo in a “One Argo” array, and expansion to include the deep ocean (>2000m), would address physical and biogeochemical research issues in a synergistic way.

The goals of the Australian BGC-Argo program include:

  1. to establish a BGC-Argo sub-facility in Australia with potential for growth

  2. to establish work flows for float acquisition, deployment and data delivery

  3. to deploy floats in areas of importance to Australia or that are currently overlooked

  4. to contribute to the global Argo program.

The success of the BGC-Argo Sub-Facility is critically dependent on interest and uptake by the Australian research community and their application of the autonomous observations to problems of national importance – in other words we need your help and will do everything to help you benefit from this research investment!

We actively seek suggestions for float deployments. Initial areas of interest include the Tasman Sea, Great Australian Bight and Southern Ocean. We are available to provide guidance on access to float data and its application. Contact us by email.

Peter Strutton
Co-leader
E: Peter.Strutton(at)utas.edu.au
Tom Trull
Co-leader & Australia’s representative to the International Biogeochemical Argo Committee
E: Tom.Trull(at)csiro.au
Christina Schallenberg
Technical Coordinator
E: Christina.Schallenberg(at)utas.edu.au