Modelling satellite-level solar-induced chlorophyll fluorescence and its comparison with OCO-2 observations

Solar Induced chlorophyll Fluorescence (SIF) is a direct measure of photosynthesis rate as it is emitted by the photosynthetic system. This paper reports a method to model SIF over India by assimilating spatial inputs (LAI, Chlorophyll content etc.) into FluorMOD leaf and canopy model. Modelled SIF was then compared to Orbiting Carbon Observatory (OCO-2) SIF observations from September 2014 to August 2015. Modelled SIF at 757 nm averaged over the country varied between 0.18 to 0.33 W m(-2) sr(-1) mu m(-1) whereas SIF at 771 nm varied between 0.10 to 0.19 W m(-2) sr(-1) mu m(-1). OCO-2 observed SIF at 757 nm averaged over the country ranged from 0.18 to 0.42 Wm(-2)sr(-1)mu m(-1). Fairly good agreement (r=0.77, p< 0.01 at 757nm; r=0.71, p< 0.05 at 771 nm) was observed between modelled and observed SIF except for summer months of April and May. This paper presents a new approach to upscale a leaf and canopy level model to estimate SIF over entire country.