Angle matters: Bidirectional effects impact the slope of relationship between gross primary productivity and sun-induced chlorophyll fluorescence from Orbiting Carbon Observatory-2 across biomes.

Written Summary: It is important to understand how sun-sensor geometry affects satellite sun-induced fluorescence (SIF) in order to take full advantage of these measurements, particularly given their close relationship with gross primary production (GPP). We displayed the bidirectionality of SIF at different viewing zenith angles in the solar principal plane and observed a clear bowl shape of SIF from the backward to forward scattering directions. Therefore, it is important to consider the bidirectionality of SIF when using OCO-2 SIF data to evaluate the SIF-GPP relationship.