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Sun-Induced Fluorescence

Demonstration product (beta version)
European Space Agency



Remotely sensed vegetation fluorescence is a promising new global proxy for GPP (Gross Primary Production), which can aid future climate predictions. Also, the Sun-Induced Fluorescence (SIF) data product can aid trace gas retrievals in the NIR wavelength region.

Other measures of vegetation like the Normalized Difference Vegetation Index use the ‘greenness’ of leaves as indicator of chlorophyll content. Unfortunately, chlorophyll content adapts slowly to stress (it can take weeks for leaves to lose their green color) and is therefore not as useful as a proxy for direct GPP. As photosynthesis is the core mechanism that drives both carbon assimilation and fluorescence, fluorescence can be exploited to serve as a more direct proxy for GPP. This allows for eyes on the short-timescale variability in terrestrial vegetation activity. During photosynthesis, sunlight is absorbed by chlorophyll pigments in leaves and converted into chemical energy. Approximately 80% of the harvested energy is used for photosynthesis. Most of the rest is dissipated non-radiatively as heat and a small fraction (~1%) is emitted at longer wavelengths as fluorescence. This SIF has a spectrally smooth signature and peaks at 737 nm.

Space based spectrometers observing this spectral region with sufficient spectral resolution and signal to noise ratio are able to detect the SIF signatures. Following recent advancements in space borne observatories, methods have been developed to disentangle the small SIF signal from radiance spectra of the GOME-2 instruments. The retrieval produces monthly averaged SIF maps on a 0.5x0.5 degree grid for the GOME-2A instrument.

SIF 2007-2016
SIF during the years 2007-2016 measured by GOME-2 on MetOp-A

Data and image archive

The GOME-2 SIF data (beta version) are provided by KNMI in the framework of the EUMETSAT Satellite Application Facility on Atmospheric Composition Monitoring (AC SAF).