The OCO-2 Solar Induced Chlorophyll Fluorescence 757 nm layer displays the fluorescence emission from land surfaces derived from in-filling of solar Fraunhofer lines in the 757 nm region of the measured spectrum. Solar Induced Chlorophyll Fluorescence (SIF) is a byproduct of plant photosynthesis and is a direct measurement of plant response during respiration. During photosynthesis, among the other light reactions, a photon can be re-emitted and this energy decay is known as chlorophyll fluorescence. SIF is a complement to existing greenness indicators such as the normalized difference vegetation index (NDVI) and can be used to serve as a functional proxy for Gross Primary Productivity (GPP).

The Orbiting Carbon Observatory-2 (OCO-2) is a three-channel imaging grating spectrometer that primarily collects cloud-free XCO₂ observations continuously over the globe by measuring reflected sunlight in the near-infrared. One of the OCO-2 channels, the O₂ A-band, contains multiple Fraunhofer lines and thus allows for the retrieval of SIF. The absorption at 757 nm is about 1.5 times larger than at 771 nm, but both values are made available for analysis. However, the blended SIF is the recommended product. The OCO-2 Solar Induced Chlorophyll Fluorescence 757 nm parameter is taken from the OCO-2 Level 2 Lite SIF product. OCO-2 makes eight simultaneous, adjacent measurements, each with a spatial resolution of 2.25 km x 1.29 km. These measurements are then mapped onto a 500 m² grid. The repeat cycle for OCO-2 is every 16 days.

References: Frankenberg et al. Prospects for chlorophyll fluorescence remote sensing from the Orbiting Carbon Observatory-2, Remote Sensing of Environment, Vol 147, 5 May. 2014, Pgs 1-12, doi: 10.1016/j.rse.2014.02.007; GES DISC - OCO-2 Documents; OCO-2 Data Center