The Fluorescence Explorer (FLEX): Mission Status and Data Exploitation Plans

The Fluorescence Explorer (FLEX) mission was selected in 2015, by the European Space Agency (ESA), as an Earth Explorer mission, with a launch planned for 2025. The main scientific objective is the quantitative global mapping of actual photosynthetic activity of terrestrial ecosystems, and its spatial/temporal variability with vegetation health status and environmental stress conditions. The very high spectral resolution measurements (0.1 nm sampling) provided by the FLORIS instrument, with a spatial resolution of 300 m, are designed to derive, as the main mission product, the spectrally resolved fluorescence emission spectrum in the range 600–780 nm. The mission is designed to fly in tandem with Copernicus Sentinel-3. The OLCI and SLSTR instruments on Sentinel-3 provide the necessary information to retrieve the emitted fluorescence, and to allow proper interpretation of the spatial and temporal dynamics of vegetation photosynthesis from such global measurements. As the launch date approaches, the scientific community is getting ready to exploit the data, developing not only the Level-1 and Level-2 data processing but also the high level data analysis strategies, involving exploitation of FLEX data, in combination with other data sources, in data assimilation schemes into global dynamical vegetation models and terrestrial carbon cycle models. This paper addresses recent developments in mission preparation, with particular focus on mission data exploitation plans.