Deep Argo

Deep Argo
Name	Deep Argo
Caption	Deep Argo float
Established	2016
Type	Oceanographic observing program
Location	Global oceans, Southern Ocean, Arctic Ocean, North Pacific, North Atlantic
Founders	Argo program, NOAA, Southern Ocean Observing System
Administered	Global Ocean Observing System, International Argo Steering Team, OceanObs

Deep Argo is an international ocean observing initiative that extends the profiling float capabilities of the Argo program into the deep and abyssal ocean, targeting depths to 6000 meters. It collects vertical profiles of temperature, salinity, dissolved oxygen, and biogeochemical properties across the World Ocean, contributing to studies related to climate change, ocean circulation, and carbon cycling. Deep Argo complements observing systems such as Argo, the Global Ocean Observing System, and regional networks coordinated by institutions like NOAA, Scripps Institution of Oceanography, and Woods Hole Oceanographic Institution.

Overview

Deep Argo builds on the legacy of Argo by deploying autonomous profiling floats capable of reaching the deep ocean, including trenches near the Mariana Trench, abyssal plains off Challenger Deep, and continental slope regions off California Current System and Kuroshio Current. The program involves collaborations among national agencies such as Japan Agency for Marine-Earth Science and Technology, CSIR, UK Met Office, and academic centers including University of Oxford, University of Washington, and Massachusetts Institute of Technology. Deep Argo data feed into global products used by Intergovernmental Panel on Climate Change, World Meteorological Organization, and International Council for the Exploration of the Sea.

History and Development

Plans for deep profiling arose from gaps identified by the Argo review panels convened by CLIVAR and GOOS. Pilot projects in the 2000s and 2010s led to prototypes by groups at Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, and JAMSTEC. Formal coordination emerged under the International Argo Steering Team and the Global Ocean Observing System with funding from agencies including National Science Foundation, European Commission Horizon 2020, NOAA, and Japan Agency for Marine-Earth Science and Technology. Field demonstrations occurred during expeditions associated with R/V Atlantis, R/V Investigator, and RRS James Cook to test operations in the Southern Ocean, North Atlantic, and Western Pacific.

Instrumentation and Technology

Deep Argo floats incorporate pressure-rated housings, high-precision conductivity-temperature sensors originally developed at Scripps Institution of Oceanography and MBARI, and oxygen sensors derived from work at Princeton University and University of Gothenburg. Engineering draws on innovations from manufacturers like Teledyne Webb Research and research groups at Laboratoire d'Océanographie de Villefranche, integrating lithium battery systems used by Argo with new pressure vessels inspired by deep-sea submersibles such as Alvin (submersible). Some floats carry bio-optical sensors produced by Wet Labs and biogeochemical packages developed in collaborations with Plymouth Marine Laboratory and Lamont–Doherty Earth Observatory. Communication relies on satellite links via the ARGOS and Iridium networks for near-real-time telemetry.

Deployment and Operations

Deployment strategies use research vessels including R/V Polarstern, RRS Sir David Attenborough, and R/V Tangaroa to place floats in target water masses like Antarctic Bottom Water, North Atlantic Deep Water, and Circumpolar Deep Water. Operations are coordinated through regional centers such as the Indian National Centre for Ocean Information Services, National Oceanography Centre, and SCRIPPS with tasking informed by observational campaigns from ICES and PICES. Floats follow cycles of profiling typically every 10 days, descending to 4000–6000 m then ascending to transmit data at the surface. Logistics integrate shiptime from programs like GEOTRACES and HOT to calibrate sensors against bottle casts from CTD rosettes.

Data Management and Applications

Deep Argo data are ingested into data systems maintained by Argo and distributed via services associated with European Centre for Medium-Range Weather Forecasts, Copernicus Marine Environment Monitoring Service, and NOAA National Centers for Environmental Information. Quality control protocols follow guidelines from the International Argo Steering Team and metadata standards used by World Data Center. Applications span assimilation into ocean reanalyses by modeling centers such as ECMWF, NOAA National Centers for Environmental Prediction, and Met Office, provision of boundary conditions for coupled models used by IPCC, and support for ecosystem assessments by IUCN and regional fisheries bodies like North Pacific Anadromous Fish Commission.

Scientific Findings and Impact

Deep Argo observations have refined estimates of global ocean heat content, informing assessments by the Intergovernmental Panel on Climate Change and contributing to studies published in journals like Nature, Science, and Geophysical Research Letters. Results reveal variability in deep warming, quantify abyssal circulation changes linked to shifts in Atlantic Meridional Overturning Circulation and Southern Ocean dynamics, and constrain carbon storage processes relevant to the Global Carbon Project. Deep Argo has enabled detection of changes associated with events such as Pacific decadal variability and provided validation for deep convection studies in regions including the Labrador Sea and Weddell Sea.

Challenges and Future Directions

Technical challenges include sensor drift, biofouling problems noted by teams at Monterey Bay Aquarium Research Institute, and limited coverage of complex bathymetry near Mid-Atlantic Ridge and continental margins. Funding and international coordination remain issues for sustained global deployment, with negotiations involving UNESCO-linked programs and national funders like NSF and DFG. Future directions emphasize expanded biogeochemical suites, integration with cabled observatories such as NEPTUNE, and synergistic operations with satellite missions including Jason series and CryoSat, as well as coupling with autonomous platforms like Seaglider and Wave Glider to achieve comprehensive deep-ocean monitoring.

Category:Oceanography