Using a Micro-AUV for Monitoring Coastal River Plume Areas

Small Autonomous Underwater Vehicles (AUVs) are proving to be a key component of coastal ocean observing systems, providing unique data sets at shallow depths and over shelf seas. This paper describes how the use of micro-AUVs improves the sampling and study of coastal areas under the influence of river plumes, as well as their advantages and limitations. Two YUCO-CTD micro-AUVs developed by the Seaber company have been deployed in these coastal river plume areas along the french coast since 2022 in the framework of the innovative MICO project and the research PPR RiOMar project. Data processing and plotting tools have been developed in Python and are freely available to the scientific community. Micro-AUVs are able to catch frontal structures and oceanic variability at small scales. They provide an interesting spatialization tool in the framework of augmented observations. Best practices for the deployment of these micro-AUVs are given, including optimal speed of 2 m.s<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>, ballast strategy in variable salinity areas, launching and recovery from different boats and the way to mimic a profiling probe. Future improvements to these systems to meet the needs of the scientific community include the addition of sensors (to measure ocean currents and biogeochemical parameters) and navigation capabilities to monitor changes ranging from extreme events to global ocean warming.