GALENE - Understanding coastal and inland ecosystem properties, processes and dynamics

Abstract

Coastal and inland aquatic ecosystems are of fundamental interest for societal and economical purposes due to a significant part of the population living there. They both highly contribute to carbon cycling and biodiversity. Those 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 are also not adapted for characterizing the biodiversity patchiness of submerged habitats and water column compositions such as phytoplankton assemblages due to their inadequate spectral resolution (e.g., Sentinel-2/MSI, Sentinel-3/OLCI). Wetland ecosystems are insufficiently described as current sensors do not adequately capture their diversity, which compromises their management and protection. A future satellite mission, so-called Global Assessment of Limnological, Estuarine and Neritic Ecosystems (GALENE), has been proposed to the Earth Explorer 11 call (ESA) to respond to the 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. GALENE will thus fill a major gap by comprehensively quantifying the state of Earth’s water bodies and aquatic ecosystems. It will substantially contribute addressing global water challenges, including water pollution and ensuring clean drinking water supply for all and protecting coastal environments and populations. GALENE mission concept consists of a synergy of three innovative instruments, namely a hyperspectral sensor, a panchromatic camera and a polarimeter. The GALENE science objectives and main technological features will be presented.