Using AUVs to study estuarine outflow stratification under severe environmental constraints

In the last few years, the technological development of underwater robotics has been a key factor to improve oceanographic research. Autonomous underwater vehicles (AUVs) are especially well suited for coastal studies because they can provide near-synoptic spatial observations. Their high spatial and temporal resolutions combined with exceptional maneuverability provide excellent conditions for AUVs dataset collection, constituting a base for new studies regarding the Sado Estuary and its adjacent coastal region. This application highlights the versatility of AUVs to survey highly dynamic regions with severe logistical constraints due to marine traffic. Results obtained in this AUVs exercise show that air temperature and solar radiation influence the local stratification, increasing the water temperature at top layers. Water temperature and salinity data also indicate that tidal estuarine ebb-flood cycle and consequent circulation plays an essential role on coastal stratification establishment.