Resumen
This paper focuses on the state of the art on Autonomous Observing Systems (AOS) used in Vessels of Opportunity (VOO) for collecting in situ atmospheric, oceanic and biogeochemical data. The designation Vessels of Opportunity includes all kinds of ships, even if not having scientific goals, which may carry proper devices that autonomously measure environmental variables. These vessels can be merchant, military, research, cruise liners, fishing, ferries, or even private yachts or sailing boats. The use of AOS can provide the opportunity for highly refined oceanographic data and improved derived data estimation, for local, regional or global scales studies. However, making the collected information accessible, both for scientific and technical purposes, provides a challenge in data management and analysis, which must, above all, ensure trusted useful data to the stakeholders. An overall review of the systems implemented is presented. This includes the definition of objectives, the recruitment of vessels and a review on the installation of proper acquisition devices; the selection and collection of Essential Oceanic Variables (EOV); the mechanisms for transmitting the information, and the quality control analysis and dissemination of data. The present and future capabilities of VOO for measuring EOV, within the Portuguese context are referred.