The US BGC-Argo programs SOCCOM and GO-BGC, which are funded by the US NSF (with additional SOCCOM support from NOAA and NASA), are making rapid progress towards the implementation of the US 500 BGC float array with 5 and 6 sensor BGC floats. These programs have a combined 293 BGC floats with 5 and 6 sensors that are currently operating (see map). An additional 15 floats have been deployed by other US programs, including the NOAA PMEL and AOML labs, for a total of 308 multi-sensor US floats operating (62% of our target). 289 of the floats are equipped with 5 BGC sensors (oxygen, nitrate, pH, chlorophyll fluorescence, and optical backscatter) and 19 also include the full, 6 sensor suite with radiometers. Floats in the array include Apex, Navis, Navis Nautilus, and the new MRV BGC SOLO-II. The floats are distributed globally.

Float numbers are changing rapidly, with 18 floats deployed in the past month and a target of more than 100 floats for the year. Plans for future deployments can be found here. With few exceptions, these floats are operating on a 10-day cycle time, with mean lifetimes exceeding 5 years for UW-built Apex floats on the standard Argo mission, including all profiles to near 2000 m.

Another major announcement is that SOCCOM project has secured an additional 3 years of funding from the NSF, extending support through 2027. After a decade of administration by Princeton U., SOCCOM will transition to the Scripps Institution of Oceanography (SIO) at UCSD, under the leadership of Pr. Lynne Talley.

In this new phase, SIO will join the University of Washington in float production, adding BGC-SOLO floats to the array. The U. of Hawaii will also join the consortium, contributing to data analysis alongside UCSD, Princeton, MBARI, U. Washington, U. Arizona, and Rutgers U. The SOCCOM project will benefit from significant improvements, including the integration of new sensors—downwelling irradiance and dual-excitation wavelength chlorophyll fluorometers. Additionally, expanding the biogeochemical state estimate to global coverage will facilitate research into the connections between the Southern Ocean and northern regions.

To date, SOCCOM’s freely accessible observational and modeling data have been utilized by researchers worldwide, resulting in over 200 internal publications and more than 50 external publications.

Initially, Argo floats were used exclusively in the open oceans. As the program developed, they began to explore marginal seas as well. The Baltic Sea is small and shallow, with a maximum depth of less than 500 meters. However, the positive experiences of Finnish and later Polish oceanographers demonstrated that this semi-enclosed sea can also be explored using Argo floats.

In September 2024, one year have passed since the deployment of the 4-variable BGC-Argo float WMO1902683 in the Gdansk Basin by the Argo-Poland consortium, led by the Institute of Oceanology of the Polish Academy of Sciences. The float was deployed as part of the Euro-Argo ERIC framework. So far, it has provided 230 profiles. It operates in a mode different from that used in the deep ocean, profiling down to the seabed every 1-2 days, with the parking depth set deeper than the maximum depth of the basin. As a result, between profiles, the float remains at the seabed, minimizing its drift.

A new paper by Xiang Yang and co-authors from the University of Tasmania and CSIRO, has compared carbon flux estimates from BGC-Argo floats and sediment traps in the Australian sector of the subantarctic Southern Ocean (figure, top panel). Using over a decade of BGC-Argo observations, the authors calculated the magnitude of three carbon pumps; the biological gravitational pump (BGP), the mixed layer pump (MLP) and the eddy subduction pump (ESP) (figure, bottom panel).

Combined with the sediment trap records from the Southern Ocean Time Series (SOTS), the organic carbon transfer efficiency was calculated to be about 3.6%, consistent with the literature. An oxygen‐based annual net community production estimate further strengthens this study and suggests the BGP and MLP make the dominant contribution to the mesopelagic carbon budget. This work emphasizes the magnitude and variability of biological carbon pumps and also highlights the importance of autonomous platforms to further improve our understanding of the global carbon budget.