Abstract
Human activities have altered the state of the ocean, leading to warming, acidification and deoxygenation. These changes impact ocean biogeochemistry and influence ecosystem functions and ocean health. The long-term global effects of these changes are difficult to predict using current satellite sensing and traditional in situ observation techniques. Autonomous platforms equipped with biogeochemical sensors allow for the observation of marine biogeochemical processes and ecosystem dynamics, covering a wide range of spatial and temporal scales. The international Biogeochemical-Argo (BGC-Argo) project is currently building a global, multidisciplinary ocean-observing network of autonomous Argo floats equipped with an extensive range of biogeochemical sensors. Other autonomous platforms, such as gliders and surface vehicles, have also incorporated such sensors, mainly operating on regional scales and near the ocean surface. Autonomous mobile assets, along with remotely sensed data, will provide the 4D information required to improve model simulations and forecasts of ocean conditions and ecosystem health.