Investigating Fraunhofer line based fluorescence retrieval in O<inf>2</inf>-B band with hyperspectral radiative transfer simulations

Abstract

The telluric O 2 -B and O 2 -A have been proved to be capable of solar-induced vegetation fluorescence (SIF) retrieval based on Fraunhofer line depth (FLD) principle. However, most FLD based algorithms mainly aim for SIF detection in O 2 -A, not suitable in O 2 -B. One of the critical reasons is that it is very difficult to model the sudden varying reflectance around O 2 -B band located in the red-edge spectral region (about 680–800 nm). In order to resolve this issue, this study proposes a new method based on the established inverted Gaussian reflectance model (IGM) and FLD principle using hyperspectral radiative transfer simulations with 1 nm bandwidth in 400–1000 nm range. Results show that the proposed method can better capture the spectrally non-linear characterization of the reflectance in 680–800 nm and thereby enables retrieval in O 2 -B, yielding much more accurate SIFs than typical FLD methods, including sFLD, 3FLD and iFLD.