title: Sun-induced fluorescence - a new probe of photosynthesis: First maps from the imaging spectrometer HyPlant.
abstract: Variations in photosynthesis still cause substantial uncertainties in predicting photosynthetic CO2 uptake rates and monitoring plant stress. Changes in actual photosynthesis that are not related to greenness of vegetation are difficult to measure by reflectance based optical remote sensing techniques. Several activities are underway to evaluate the sun-induced fluorescence signal on the ground and on a coarse spatial scale using space-borne imaging spectrometers. Intermediate-scale observations using airborne-based imaging spectroscopy, which are critical to bridge the existing gap between small-scale field studies and global observations, are still insufficient. Here we present the first validated maps of sun-induced fluorescence in that critical, intermediate spatial resolution, employing the novel airborne imaging spectrometer HyPlant. HyPlant has an unprecedented spectral resolution, which allows for the first time quantifying sun-induced fluorescence fluxes in physical units according to the Fraunhofer Line Depth Principle that exploits solar and atmospheric absorption bands. Maps of sun-induced fluorescence show a large spatial variability between different vegetation types, which complement classical remote sensing approaches. Different crop types largely differ in emitting fluorescence that additionally changes within the seasonal cycle and thus may be related to the seasonal activation and deactivation of the photosynthetic machinery. We argue that sun-induced fluorescence emission is related to two processes: (i) the total absorbed radiation by photosynthetically active chlorophyll; and (ii) the functional status of actual photosynthesis and vegetation stress.
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Rascher
authors.affiliation: Department of Earth Physics and Thermodynamics, University of Valencia, Dr Moliner 50 46100 Burjassot, Valencia, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Alonso
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Burkart
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.|Remote Sensing of Environmental Dynamics Lab, DISAT, Università degli Studi Milano-Bicocca, Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Cilia
authors.affiliation: Remote Sensing of Environmental Dynamics Lab, DISAT, Università degli Studi Milano-Bicocca, Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cogliati
authors.affiliation: Remote Sensing of Environmental Dynamics Lab, DISAT, Università degli Studi Milano-Bicocca, Milano, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Colombo
authors.affiliation: Remote Sensing Laboratories, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Damm
authors.affiliation: European Space Agency (ESA), ESTEC, Keplerlaan 1, 2200 AG, Noordwijk, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Drusch
authors.affiliation: Institute for Space Sciences, Free University of Berlin, Carl-Heinrich-Becker-Weg 6-10, 12165, Berlin, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Guanter
authors.affiliation: Global Change Research Centre AS CR, Bělidla 986/4a, 603 00, Brno, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Hanus
authors.affiliation: Specim Spectral Imaging Ltd., Teknologiantie 18A, 90590, Oulu, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Hyvärinen
authors.affiliation: Remote Sensing of Environmental Dynamics Lab, DISAT, Università degli Studi Milano-Bicocca, Milano, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Julitta
authors.affiliation: Specim Spectral Imaging Ltd., Teknologiantie 18A, 90590, Oulu, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Jussila
authors.affiliation: Specim Spectral Imaging Ltd., Teknologiantie 18A, 90590, Oulu, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Kataja
authors.affiliation: Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236, Athens, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Kokkalis
authors.affiliation: European Space Agency (ESA), ESTEC, Keplerlaan 1, 2200 AG, Noordwijk, the Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Kraft
authors.affiliation: Field Lab Campus Klein-Altendorf, Agricultural Faculty, University of Bonn, Klein-Altendorf 3, 53359, Rheinbach, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kraska
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Matveeva
authors.affiliation: Department of Earth Physics and Thermodynamics, University of Valencia, Dr Moliner 50 46100 Burjassot, Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Moreno
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Muller
authors.affiliation: Remote Sensing of Environmental Dynamics Lab, DISAT, Università degli Studi Milano-Bicocca, Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Panigada
authors.affiliation: Global Change Research Centre AS CR, Bělidla 986/4a, 603 00, Brno, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Pikl
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Pinto
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Prey
authors.affiliation: Field Lab Campus Klein-Altendorf, Agricultural Faculty, University of Bonn, Klein-Altendorf 3, 53359, Rheinbach, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Pude
authors.affiliation: Remote Sensing of Environmental Dynamics Lab, DISAT, Università degli Studi Milano-Bicocca, Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Rossini
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schickling
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, Leo-Brandt-Str., 52425, Jülich, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Schurr
authors.affiliation: European Space Agency (ESA), ESTEC, Keplerlaan 1, 2200 AG, Noordwijk, the Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Schüttemeyer
authors.affiliation: Department of Earth Physics and Thermodynamics, University of Valencia, Dr Moliner 50 46100 Burjassot, Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Verrelst
authors.affiliation: Global Change Research Centre AS CR, Bělidla 986/4a, 603 00, Brno, Czech Republic.
authors.forename: F
authors.initials: F
authors.lastname: Zemek
mesh_terms: D002734:Chlorophyll / Q000502:physiology*; D005453:Fluorescence; D010788:Photosynthesis; D058998:Remote Sensing Technology / Q000379:methods*; D013050:Spectrometry, Fluorescence; D013472:Sunlight
chemical_list: D002734:Chlorophyll
keywords: FLEX; HyPlant; airborne measurements; chlorophyll fluorescence; imaging spectroscopy; photosynthesis; remote sensing; sun-induced fluorescence; vegetation monitoring