Continuous and long-term measurements of reflectance and sun-induced chlorophyll fluorescence by using novel automated field spectroscopy systems

In this paper we present novel automated field spectroradiometers for collecting unattended, continuous and long-term measurements of plant canopies and, more in general, of Earth’s ecosystems. These systems simultaneously collect high and ultra-high resolution spectra in the visible to near-infrared (VNIR) domain employing two spectrometers: i) the first covers the spectral range 400-1000 nm with a 1.0 nm spectral resolution; ii) the second provides a sub-nanometer spectral resolution within the 700-800 nm spectral range. The data collected by the first spectrometer allow retrieval of VNIR reflectance, while the higher spectral resolution data from the second device permit estimation of vegetation Sun-Induced Fluorescence (SIF) in the O2-A band. The instruments are constructed by assembling commercial and on-the-shelf optical optoelectronic devices to facilitate reproduction of the instrument for promoting measurements over different ecosystems. The instrument’s optical design, data collection and processing, laboratory and field calibration methods are reported and discussed. The high spectral resolution and the rigorous calibration methods enable accurate estimation of SIF in physical units by exploiting almost the same retrieval concept as that of the European Space Agency FLuorescence EXplorer mission. Reliability of the radiance, reflectance and fluorescence measurements collected by the Multiplexer Radiometer Irradiometer (MRI) and its compacted version (SFLUOR box) are tested in several field campaigns to: i) collect continuous measurements during the vegetation growing season; ii) calibrate/validate the novel airborne HyPlant imager. The datasets of canopy reflectance, vegetation indices and sun-induced fluorescence collected are shown and discussed.

COGLIATI Sergio;  ROSSINI Micol;  JULITTA Tommaso;  MERONI Michele;  SCHICKLING Anke;  BURKARF A;  PINTO Francisco;  RASCHER Uwe;  COLOMBO Roberto; 

2015-12-02

ELSEVIER SCIENCE INC

JRC94298

0034-4257,   

http://www.sciencedirect.com/science/article/pii/S0034425715001248,    https://publications.jrc.ec.europa.eu/repository/handle/JRC94298,   

10.1016/j.rse.2015.03.027,