6533b825fe1ef96bd1281c44

RESEARCH PRODUCT

Atmospheric and Instrumental Effects on the Fluorescence Remote Sensing Retrieval

subject

description

Accurately disentangling the tiny Solar–Induced Chlorophyll Fluorescence (SIF) from canopy reflected solar irradiance by using passive remote sensing techniques is always challenging. Regardless the scale at which SIF is measured, i.e., proximal sensing, airborne or satellite level; instrumental and atmospheric effects must be accounted for and compensated as part of the SIF retrieval strategy. Regarding the instrumental effects, the use of very high spectral resolution spectrometers makes mandatory an accurate characterization of the Instrument Spectral Response Function (ISRF); and – in the case of imager spectrometers – an accurate characterization of the full instrument response in the spectral and in the spatial domain. Otherwise, spectral distortions derived by an inaccurate instrument's response characterization would rapidly derive into errors on SIF estimations. With regards to the atmospheric effects, when exploiting the oxygen absorption features to estimate SIF, aerosol characterization generally becomes the bottleneck of the atmospheric correction strategy due to its strong impact on these spectral regions. In this work, instrumental and atmospheric effects are analyzed twofold: (1) focusing on their detection by inspecting the at–sensor radiance and surface apparent reflectance, and (2) proposing an atmospheric and instrument compensation strategy to mitigate these effects.