Potential of the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor for the monitoring of terrestrial chlorophyll fluorescence

摘要

Global monitoring of sun-induced chlorophyll fluorescence (SIF) is improvingour knowledge about the photosynthetic functioning of terrestrial ecosystems.The feasibility of SIF retrievals from spaceborne atmospheric spectrometershas been demonstrated by a number of studies in the last years. In this work,we investigate the potential of the upcoming TROPOspheric MonitoringInstrument (TROPOMI) onboard the Sentinel-5 Precursor satellite mission forSIF retrieval. TROPOMI will sample the 675–775 nm spectral window with aspectral resolution of 0.5 nm and a pixel size of 7 km × 7 km. Weuse an extensive set of simulated TROPOMI data in order to assess theuncertainty of single SIF retrievals and subsequent spatio-temporalcomposites. Our results illustrate the enormous improvement in SIF monitoringachievable with TROPOMI with respect to comparable spectrometers currentlyin-flight, such as the Global Ozone Monitoring Experiment-2 (GOME-2)instrument. We find that TROPOMI can reduce global uncertainties in SIFmapping by more than a factor of 2 with respect to GOME-2, which comes togetherwith an approximately 5-fold improvement in spatial sampling. Finally, we discuss thepotential of TROPOMI to map other important vegetation parameters at a globalscale with moderate spatial resolution and short revisit time. Those includeleaf photosynthetic pigments and proxies for canopy structure, which willcomplement SIF retrievals for a self-contained description of vegetationcondition and functioning.