B) Interpretation and exploitation of global fluorescence data
We evaluate the potential of the derived global fluorescence data sets as a proxy for vegetation photosynthesis and gross primary production (GPP, output from photosynthesis). Because of the coarse spatial resolution of the global data sets currently available, we mostly rely on a data-driven approach, in which we compare fluorescence with other relevant data sets, such as space-based vegetation indices and geophysical parameters derived from spectral reflectance measurements, GPP estimates from carbon models and a range of meteorological parameters expected to drive vegetation photosynthesis at the synoptic scale.
Two main questions to be answered by this research are: (i) how can we link our space-based top-of-canopy fluorescence measurements to GPP on a global scale, and (ii) where and under which conditions the fluorescence observations can provide a better handle for vegetation functioning than other existing data sets like vegetation indices. We performe specific studies on those areas where we identify that fluorescence data can be particularly useful, such as large cropland areas and boreal forests, in order to gain a better understanding of the terrestrial carbon cycle through fluorescence data.