State-of-the-art satellite vegetation fluorescence retrievals and comparisons with reflectance-based bio-spectral indicators

Global mapping of far-red (755-770 nm) terrestrial vegetation fluorescence from space has recently been accomplished by utilizing the filling-in of solar Fraunhofer line and measurements from a high spectral resolution interferometer on the Japanese Greenhouse gases Observing SATellite (GOSAT). Strong evidence of vegetation fluorescence at a longer wavelength (866 nm) has also been shown with a lower spectral resolution spectrometer, the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument, aboard the EnviSat. These data are of interest because they can potentially provide global information on the functional status of vegetation including light-use efficiency and global primary productivity that can be used for global carbon cycle modeling. In this work we will explore different methods of retrieving chlorophyll fluorescence from space, including the use of different spectral windows. We present state-of-the-art fluorescence retrievals from GOSAT and other satellite sensors and compare the spatio-temporal variations of these data sets with those from popular reflectance-based bio-spectral vegetation indicators such as the Normalized Difference Vegetation Index (NDVI) and the Photochemical Reflectance Index (PRI).