After a series of rigorous tests, a BioGeoChemical (BGC) float, used by Euro-Argo ERIC in ocean observations, is now fully prepared for a GEORGE deployment taking place in June at the Porcupine Abyssal Plain Sustained Observatory (PAP) site off the coast of the United Kingdom. The PAP deployment will be one of the largest ones made in the project and will include sensor testing on multiple platforms. In March, Euro-Argo ERIC successfully tested the float at the Ifremer facility in Brest, France, ensuring its readiness for this crucial mission.
The Euro-Argo ERIC Office team conducted trials in a 20-meter-deep tank, to validate the GEORGE float’s mission settings, hydraulic performance, satellite transmission and sensor data collection. Throughout 10 complete cycles – comprising both descent and resurfacing – the float demonstrated its capability to measure dissolved oxygen and pH in addition to the usual parameters of pressure, temperature and salinity. The float is now set for the deployment in June 2025.
“For its initial phase, it will carry out high-resolution profiles during the GEORGE experiment at PAP site, before transitioning to the regular Argo mission, where it will perform ocean observations in the region for several years”, says Operational Engineer Romain Cancouët from Euro-Argo.
Euro-Argo ERIC test of the GEORGE BGC float in the Ifremer tank. Photo credits: Euro-Argo ERIC.
What is the GEORGE experiment at PAP site?
In addition to the development of novel autonomous sensor technologies for integration on fixed and mobile platforms, one of the primary objectives of the GEORGE project is to enhance spatio-temporal resolution, coverage and continuity of marine observations. This initiative enables targeted and adaptive monitoring of key observed regions.
In that context, Euro-Argo ERIC will deploy this BGC float at the Porcupine Abyssal Plain (PAP) Sustained Observatory site during field trials in June 2025. This deployment will contribute to the characterisation of the carbonate system by using multiple ocean observing platforms operated by the three involved Research Infrastructures (Euro-Argo, ICOS, EMSO). Data collected from this experiment will undergo calibration using bottle samples obtained from the research vessel. These calibrated datasets will then be examined to determine the optimal set of observations to define air-sea flux, thereby informing broader discussions on the design of ocean observing systems.
Positions (yellow dots) of the Argo profiles measuring pH collected the last month in the West European Basin. Source: https://dataselection.euro-argo.eu/. Location (blue triangle) of the deployment of the Euro-Argo BGC float during the PAP cruise in June 2025. Photo credits: Euro-Argo ERIC.
This deployment will increase geochemistry observations from depths of 2 000 meters up to the surface (the float will measure pressure, temperature, salinity, dissolved oxygen and pH from 2000 m to the surface) in this sector of the Atlantic. Additionally, it will enable cross-comparisons with other observing platforms and sensors, including Sailbuoy and glider. Currently, only a limited number of Argo floats in this region are equipped to measure pH, making this deployment particularly significant.
The float is expected to collect pH observations with improved quality with this updated version of the Sea-Bird Scientific SeaFET sensor, which addresses technical issues encountered in the previous years.
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