Abstract
Remote sensing (RS) of sun-induced fluorescence (SIF) has emerged as a promising indicator of photosynthetic activity and related stress from the leaf to the ecosystem level. The implementation of modern RS technology on SIF is highly motivated by the direct link of SIF to the core of photosynthetic machinery. In the last few decades, a lot of studies have been conducted on SIF measurement techniques, retrieval algorithms, modeling, application, validation, and radiative transfer processes, incorporating different RS observations (i.e., ground, unmanned aerial vehicle (UAV), airborne, and spaceborne). These studies have made a significant contribution to the enrichment of SIF science over time. However, to realize the potential of SIF and to explore its full spectrum using different RS observations, a complete document of existing SIF studies is needed. Considering this gap, we have performed a detailed review of current SIF studies from the ground, UAV, airborne, and spaceborne observations. In this review, we have discussed the in-depth interpretation of each SIF study using four RS platforms. The limitations and challenges of SIF studies have also been discussed to motivate future research and subsequently overcome them. This detailed review of SIF studies will help, support, and inspire the researchers and application-based users to consider SIF science with confidence.
Highlights
Sun-induced fluorescence (SIF) is a novel remote sensing (RS) signal for monitoring global vegetation status, encompassing its structural and functional activity from the canopy to ecosystem levels [1,2]
Meroni et al [1] suggested that the instrument calibration process should pass through the comparison of a measured raw incident irradiance spectrum with modeled values obtained from high-resolution Millimetre-wave Atmospheric-Retrieval Code (MARC) [70]
We have provided an in-depth review of existing SIF studies from the ground, unmanned aerial vehicle (UAV), airborne and spaceborne measurements
Summary
Sun-induced fluorescence (SIF) is a novel remote sensing (RS) signal for monitoring global vegetation status, encompassing its structural and functional activity from the canopy to ecosystem levels [1,2]. The plant molecules absorb solar energy in the form of photons, and on the absorption of photons, the molecules get into their excited state. The highly energetic excited molecules release energy through vibration relaxation and photon emission, which is called fluorescence [3]. The full stretch of the SIF spectrum covers the wavelengths ranging between visible (VIS) to near-infrared (NIR) spectrum of 640–800 nm. Both PS II and PS I operate in a sequence and are commonly measured by two peak signals [6] identified by their usual wavelength positions at SIF690 and SIF760 for PS II and PS I, Sensors 2020, 20, 1144; doi:10.3390/s20041144 www.mdpi.com/journal/sensors
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have