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www.sea-technology.com February 2016 / st 21 T here is a growing scientifc demand for instruments that can monitor the physi- cal and biogeochemical processes of coastal water masses in real time. However, few plat- forms are available for this kind of monitoring, particularly for long-term observations that last from a few months to a few years. To meet this need, the Department of Tech- nology Research and Development at the French Research Institute for Exploitation of the Sea (Ifremer) developed a coastal profling foat named Arvor-C to monitor the change in temperature and salinity in coastal seas. A previous article in Sea Technology (February 2010) details its operation and performance. Although this platform has offered valuable services for several years, researchers now need an enhanced coastal exploration instru- ment to record more parameters, including dissolved oxygen, turbidity and fuorimetry. Due to its design, the standard Arvor-C profl- ing foat cannot accommodate additional sensors. For this reason, Ifremer, in collaboration with nke Instru- mentation, designed a new, multisensor coastal profling foat: the Arvor-Cm, which can embed additional sensors easily in terms of mechanical integration, hardware archi- tecture and software development. From Arvor-C to Arvor-Cm The Arvor-C profling foat was designed by Ifremer a few years ago to meet the needs of scientists for high-frequency data acquired over long periods of time at the same location in a coastal environment. It is based on the Arvor/Provor profling foats, which have been deployed for offshore ap- plications for more than 20 years, particularly in the frame of the Argo international program. Profling foats are more reliable and easier to set up than instruments moving along moored cables, and do not require particular attention or skills to monitor their operation, in contrast to gliders. The Arvor-C profling foat has been successfully oper- ated in the Bay of Biscay since 2009, recording more than 2,300 profles (as of February 2016) as part of the Aquitaine/ Armorican Shelves and Slopes Physics Experiment (ASPEX) project. The deployment positions, one in the northern part of the bay and one in the southern part, were chosen to collect profles representing the hydrological properties of the "cold pool" extending above Armorican and Aqui- taine shelves. The Arvor-C, equipped with a Sea-Bird CTD SBE41CP sensor, has been used to study the annual cycle and the seasonal stratifcation over these regions with high temporal resolution. The anti-drift claws on the bottom-end cap of the Arvor- C foat have proved effective at sea: the drift of the foat is limited to 200 m per day on average, making it appropriate for coastal applications. These successful deployments show that the Arvor-C-type platform fulflls the scientifc needs in monitoring coastal Arvor-Cm: A Multisensor Coastal Profling Float Real-Time Monitoring of Biogeochemical Parameters in Coastal Seas By Xavier André • Vincent Dutreuil • Serge Le Reste Arvor-Cm deployment in the Bay of Vilaine, France. (Inset) Close-up of the Arvor-Cm upper-end cap. (Photo Credit: Olivier Dugornay, Ifremer)