Biogeochemical Argo

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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.

Access data

The goal

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.

Data collection

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.

Why it’s important

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.

Key data streams

Useful information

Global biogeochemical argo array

Access to global Biogeochemical Argo data is via two Global Data Access Centres (GDACs); one located in Monterey, USA (USGODAE) and the other in Brest, France (CORIOLIS). Both GDACs hold the complete Argo data collection. Data can be selected using a latitude/longitude region and a time range or by Data Centre (DAC) or ocean region. The data at the GDACs are in netcdf format with profile, trajectory, technical and meta files available for each float.

Global Biogeochemical Argo data is available through two Global Data Access Centres (GDACs) in netcdf format:

United States Global Access Centre

French Global Access Centre

Global network status map of operational Biogeochemical Argo floats

Global mission

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:

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

Australian implementation

The goals of the Australian BGC-Argo program include:

to establish a BGC-Argo sub-facility in Australia with potential for growth
to establish work flows for float acquisition, deployment and data delivery
to deploy floats in areas of importance to Australia or that are currently overlooked
to contribute to the global Argo program.

Useful links

Get involved

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.

The IMOS BGC-Argo sub-facility also seeks to enable successful profiling float deployments throughout the Australian community, and is willing to provide associated support to meet this goal, within the constraints of available resources and the following principles:

1. Collaborators must commit to Argo principles, including pre-deployment registration, public data access via GDACs in netCDF format, and contributing to the core 10-day 2000-m mission, targeting achieving 200 profiles.

2. Floats must be deployed in regions of utility to complete or maintain the global Argo array of core, deep and BGC floats, and thus should be coordinated with other Argo float deployment plans. If conditions 1 and 2 are met, then float pre-deployment checks, real time data handling, and delayed mode quality control will be supported by the IMOS BGC-Argo sub-facility.

3. Telecommunication costs should in general be covered by the float providers. For operators seeking to deploy floats for process studies with non-standard missions, that later transition to the standard Argo mission, it may be possible for IMOS BGC-Argo to contribute to telecommunication costs, subject to fund availability and float utility to the global Argo array. In these cases, telecoms accounts should be arranged by the providers, with financial contributions to then be provided from IMOS funds.

Contact

Christina Schallenberg
Research Associate and Delayed Mode QC Operator
E: [email protected]

Operating institution

CSIRO · University of Tasmania

Co-investors

Marine National Facility

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Acknowledging IMOS

Users of IMOS data are required to clearly acknowledge the source material by including the following statement:
Australia’s Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent.