GALENE

Coastal and inland aquatic ecosystems are of fundamental interest to society and economy, given their tight link to urbanization and economic value creation. They play a significant role in the carbon cycle, and they comprise critical habitats for biodiversity. Aquatic ecosystems are continuously impacted by natural processes and human activities. Many of these impacts become more frequent and severe, particularly with increasing population and climate change. Hence, there is a need (i) to generate reliable, robust and timely evidence of how these environments are changing, (ii) to understand processes causing these changes and their societal, health, and economic consequences, and (iii) to identify steps towards conservation, restoration and sustainable use of water and dependent ecosystems, and resources. Systematic, high-quality and global observations, such as those provided by satellite remote sensing techniques, are key to understand complex aquatic systems. While multitudes of remote sensing missions have been specifically designed for studying ocean biology and biogeochemistry as well as for evaluating terrestrial environments, remote sensing missions dedicated to studying critical coastal and inland aquatic ecosystems at global scale are non-existent. Thus, these ecosystems remain among the most understudied habitats on the Earth’s surface. Specific reasons for such an observational gap lie in the dynamic and optical complexity of water ecosystems, in combination with technological challenges to optimize the relevant spatial, spectral, radiometric, and temporal characteristics. Current and forthcoming missions are either not suited to provide a global coverage (e.g., PRISMA, EnMAP) or to obtain reliable data over dark waters (e.g., carbon-rich lakes) due to inadequate radiometric sensitivity (e.g., Sentinel-2/MSI). They also fall short of requirements for characterizing biodiversity variables such as benthic habitat structure and phytoplankton assemblages due to their inadequate spatial and spectral resolution, respectively. A future satellite mission, the so-called Global Assessment of Limnological, Estuarine and Neritic Ecosystems (GALENE), is proposed to respond to current and future challenges linked to coastal and inland ecosystems. GALENE will provide optimized measurements of these aquatic ecosystems, and enable an adaptive sampling of dynamic properties and processes in water columns, benthic habitats and associated wetlands. The GALENE mission concept consists of a synergy of three innovative instruments, namely a hyperspectral sensor, a panchromatic camera and a polarimeter.