Argo floats

Argo floats
Name	Argo float
Caption	Profiling autonomous oceanographic float
Inventors	Roger Samelson; Claude Lorius; development by Scripps Institution of Oceanography and CNRS
Introduced	1990s
Manufacturer	Teledyne Webb Research; Provor (NKE Instrumentation)
Use	autonomous ocean profiling
Country	International
Discipline	Oceanography

Argo floats Argo floats are globally distributed autonomous profiling instruments that record oceanographic properties while drifting with currents and periodically changing depth. They provide sustained, real-time observations that support research by institutions such as National Oceanic and Atmospheric Administration, European Commission programs, and initiatives coordinated through the Argo international program. Invented and implemented through partnerships among Scripps Institution of Oceanography, CNRS, and manufacturers like Teledyne Webb Research, floats transformed modern studies by enabling synoptic coverage of the Pacific Ocean, Atlantic Ocean, Indian Ocean, and polar seas.

Overview

Argo floats occupy the upper 2,000 metres of the global ocean, sampling temperature, salinity, and derived density while transmitting data via satellite to agencies including NOAA and EUMETSAT. The network complements ship-based programs such as the Global Ocean Ship-Based Hydrographic Investigations Program and satellite missions from NASA and European Space Agency by delivering in situ profiles that underpin datasets like the World Ocean Atlas. Supported by national programs from Japan Agency for Marine-Earth Science and Technology, CSIRO, UK Met Office, and others, the program contributes to operational products used by National Weather Service and research on phenomena such as El Niño–Southern Oscillation and Atlantic Meridional Overturning Circulation.

Design and Operation

A typical float comprises a pressure housing, buoyancy engine, sensors, battery pack, and satellite transmitter built by manufacturers such as Teledyne Webb Research and Provor. Programming and mission planning often utilize resources from Scripps Institution of Oceanography, Institute of Ocean Sciences (Canada), and laboratories within CNRS to set cycle depth, parking depth, and sampling cadence. Deployment is executed from research vessels like RV Knorr or merchant ships under coordination with centers such as the Argo Data Management Team and national data centers including Japan Meteorological Agency. Communication uses satellite constellations such as Argos (satellite system) and Iridium to route profiles to operational centers like Global Telecommunication System hubs.

Data and Measurements

Floats measure ocean temperature and salinity using sensors from vendors tied to laboratories at Scripps Institution of Oceanography and calibration facilities at National Institute of Standards and Technology. Profiles are quality-controlled by regional centers affiliated with IOCARIBE-related networks, Euro-Argo nodes, and national agencies including NOAA and Bureau of Meteorology (Australia). The data stream feeds assimilation into models run by ECMWF, NOAA National Centers for Environmental Prediction, and seasonal forecast systems addressing El Niño–Southern Oscillation and Indian Ocean Dipole. Derived products support climatologies such as World Ocean Atlas and analyses of heat content used in studies referencing IPCC assessments.

Deployment and Fleet Management

Global deployment strategies are coordinated at international meetings convened by Argo's steering groups and endorsed by bodies like IOC of UNESCO and panels of WMO. Nation-state contributors, including United States Department of Commerce, Ministry of Land, Infrastructure, Transport and Tourism (Japan), and Department of the Environment (UK), fund regional arrays maintained by institutions such as Scripps Institution of Oceanography and Ifremer. Fleet management addresses drift profiling coverage in basins like the Southern Ocean and marginal seas such as the Mediterranean Sea, with deployment platforms ranging from Australian RV Investigator cruises to commercial container ships under programs like the Global Shipping Watch-style partnerships.

Scientific and Operational Applications

Argo float observations underpin research in climate change, supporting analyses of global ocean heat uptake cited in IPCC reports and studies of variability associated with El Niño–Southern Oscillation, Pacific Decadal Oscillation, and Atlantic Multidecadal Oscillation. Operational uses include improving ocean state estimates for forecasting centers such as ECMWF and NOAA National Hurricane Center and supporting fisheries management by agencies like NOAA Fisheries. Data have enabled discoveries in mesoscale dynamics studied at institutions like Lamont–Doherty Earth Observatory and investigations of deep convection events linked to phenomena observed near Labrador Sea and Weddell Sea.

Limitations and Challenges

Limitations include sensor drift, biofouling, battery lifetime, and sparse coverage in marginal or ice-covered regions, which require technical solutions developed by laboratories including Scripps Institution of Oceanography, Ifremer, and manufacturers like NKE Instrumentation. Challenges also arise from international data coordination among entities such as Argo governance bodies, IOC panels, and national funders, plus integration with satellite missions by NASA and European Space Agency. Ongoing developments aim to extend profiling depth, add biogeochemical sensors tested in projects led by NOAA Pacific Marine Environmental Laboratory and CNRS, and expand polar capabilities through collaborations with British Antarctic Survey and Alfred Wegener Institute.

Category:Oceanographic instruments