Dr. Oded Liran

Chlorophyll fluorescence can be remotely sensed via the Fraunhofer atmospheric absorption lines of oxygen and is termed Solar-Induced Fluorescence (SIF). SIF has been extensively related to carbon assimilation at global ecology scale and was interpreted as Electron Transport Rate (ETR). However, SIF was shown to be unrelated directly to carbon assimilation at finer-scale resolution and may be related to other photosynthetic processes, such as non-photochemical quenching. To this end, we defined a novel Remote Sensing Electron Transport Rate index (RS-ETRi) based on a combination of three parameters: SIF, Normalized Differential Vegetation Index (NDVI) and light intensity. It is shown that ETR increased with light intensity in C3 crop, and assumed a linear relationship between the photosynthetic activity and light intensity, with a correlation of R2 = 0.99 to a portable fluorometer. Moreover, RS-ETRi correlated with other traditional vegetation indices of crop structure and stress. In the following step a formulation was devised of how each part of the photochemical mechanism and light energy utilization processes are manifested within this index. Given that the index is constructed from spectral bands that can also be measured from earth observatory system, it will be interesting to see how a scaling down of this index in spatial resolution to a continent level will contribute to our understanding on trends of global warming and climate change