Mineral Luminescence Observed From Space

Phillipp Koehler1, Woodward Fischer1, George Rossman1, John Grotzinger1, Russell Doughty1, Yujie Wang1, Yi Yin1, Christian Frankenberg1,2

1Division of Geological and Planetary Sciences California Institute of Technology, Pasadena, CA, USA
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA


Methods developed to explore the luminescent properties of the moon facilitated the development of techniques to infer terrestrial solar-induced chlorophyll fluorescence (SIF) from satellite instruments. While single SIF retrievals are inherently noisy, averaging many retrievals allows us to obtain highly accurate estimates. We analyzed several years of aggregated SIF data collected by the TROPOspheric Monitoring Instrument (TROPOMI) and the Orbiting Carbon Observatory-2 (OCO-2) over non-vegetated areas to explore the potential of SIF retrievals beyond the realm of photosynthesis. The fundamentally different retrievals at varying wavelengths in the near-infrared reveal that about 10% of all barren surfaces are weakly luminescent, while a few areas luminesce strongly- amounts comparable to SIF from vegetation. By means of lithological maps, we attribute the strongest luminescence signals to exposed carbonate and evaporite sedimentary rocks. Besides a detailed evaluation of the signal properties, we discuss implications for SIF data sets and other remote sensing products.