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1. Modelling LAI, surface water and carbon fluxes at high-resolution over France: comparison of ISBA-A-gs and ORCHIDEE

Author

Sébastien Lafont, Yue Zhao, Fabienne Maignan, Jean-Christophe Calvet, Marie Weiss, Philippe Peylin, P. Ciais, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), European Commission within the GMES initiative, The publication of this article is financed by CNRS-INSU, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, LEAF-AREA INDEX, CYCLOPES GLOBAL PRODUCTS, LAND-SURFACE, SOUTHWESTERN FRANCE, CLIMATE MODELS, ECOSYSTEM RESPIRATION, VEGETATION MODEL, EUROPEAN FORESTS, SATELLITE DATA, SOIL-MOISTURE, [SDV]Life Sciences [q-bio], lcsh:Life, 0207 environmental engineering, 02 engineering and technology, Land cover, 01 natural sciences, lcsh:QH540-549.5, medicine, Leaf area index, 020701 environmental engineering, Water content, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Earth-Surface Processes, Transpiration, lcsh:QE1-996.5, 15. Life on land, Seasonality, medicine.disease, Canopy conductance, lcsh:Geology, lcsh:QH501-531, 13. Climate action, [SDU]Sciences of the Universe [physics], Climatology, [SDE]Environmental Sciences, Environmental science, Climate model, lcsh:Ecology, Ecosystem respiration
Abstract

The Leaf Area Index (LAI) is a measure of the amount of photosynthetic leaves and governs the canopy conductance to water vapor and carbon dioxide. Four different estimates of LAI were compared over France: two LAI products derived from satellite remote sensing, and two LAI simulations derived from land surface modelling. The simulated LAI was produced by the ISBA-A-gs model and by the ORCHIDEE model (developed by CNRM-GAME and by IPSL, respectively), for the 1994–2007 period. The two models were driven by the same atmospheric variables and used the same land cover map (SAFRAN and ECOCLIMAP-II, respectively). The MODIS and CYCLOPES satellite LAI products were used. Both products were available from 2000 to 2007 and this relatively long period allowed to investigate the interannual and the seasonal variability of monthly LAI values. In particular the impact of the 2003 and 2005 droughts were analyzed. The two models presented contrasting results, with a difference of one month between the average leaf onset dates simulated by the two models, and a maximum interannual variability of LAI simulated at springtime by ORCHIDEE and at summertime by ISBA-A-gs. The comparison with the satellite LAI products showed that, in general, the seasonality was better represented by ORCHIDEE, while ISBA-A-gs tended to better represent the interannual variability, especially for grasslands. While the two models presented comparable values of net carbon fluxes, ORCHIDEE simulated much higher photosynthesis rates than ISBA-A-gs (+70 %), while providing lower transpiration estimates (−8 %).

Published
2018
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2. PROSPECT and SAIL models: a review of use for vegetation characterization

Author

Pablo J. Zarco-Tejada, Susan L. Ustin, C. François, Frédéric Baret, Stéphane Jacquemoud, Wout Verhoef, Gregory P. Asner, Cédric Bacour, Faculty of Geo-Information Science and Earth Observation, Department of Natural Resources, Department of Water Resources, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), National Aerospace, Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Global Ecology, Carnegie Institution for Science [Washington], Ecologie Systématique et Evolution (ESE), Université Paris-Sud - Paris 11 (UP11)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), University of California [Davis] (UC Davis), University of California, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Carnegie Institution for Science, and University of California (UC)

Subjects
Canopy, [SPI.OTHER]Engineering Sciences [physics]/Other, NRS, 010504 meteorology & atmospheric sciences, ADLIB-ART-2848, 0211 other engineering and technologies, Soil Science, Context (language use), 02 engineering and technology, WRS, water-content, 01 natural sciences, DIRECTIONAL REFLECTANCE, Laboratory of Geo-information Science and Remote Sensing, leaf optical-properties, Radiative transfer, RELATION PLANTE-SOL, Laboratorium voor Geo-informatiekunde en Remote Sensing, remote-sensing data, Computers in Earth Sciences, Leaf area index, SPECTRAL REFLECTANCE, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, Radiative transfer modeling, Geology, Vegetation, 15. Life on land, PE&RC, Reflectivity, Characterization (materials science), radiative-transfer models, chlorophyll content, bidirectional reflectance, Environmental science, canopy reflectance models, VEGETATION, RADIATIVE TRANSFER MODELS, area index, cyclopes global products, sugar-beet canopies
Abstract

International audience; The combined PROSPECT leaf optical properties model and SAIL canopy bidirectional reflectance model, also referred to as PROSAIL, has been used for about sixteen years to study plant canopy spectral and directional reflectance in the solar domain. PROSAIL has also been used to develop new methods for retrieval of vegetation biophysical properties. It links the spectral variation of canopy reflectance, which is mainly related to leaf biochemical contents, with its directional variation, which is primarily related to canopy architecture and soil/vegetation contrast. This link is key to simultaneous estimation of canopy biophysical/structural variables for applications in agriculture, plant physiology, or ecology, at different scales. PROSAIL has become one of the most popular radiative transfer tools due to its ease of use, general robustness, and consistent validation by lab/field/space experiments over the years. However, PROSPECT and SAIL are still evolving: they have undergone recent improvements both at the leaf and the plant levels. This paper provides an extensive review of the PROSAIL developments in the context of canopy biophysics and radiative transfer modeling

Published
2009
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3. International Journal of Applied Earth Observation and Geoinformation Intercomparison and quality assessment of MERIS, MODIS and SEVIRI FAPAR products over the Iberian Peninsula

Author

Martínez, B, Camacho, F, Verger, A, Garcia-Haro, Javier, Gilabert, M.A, IPLA CSIC, Dept Technol & Biotechnol Dairy Prod, Dairy Safe Grp, Instituto de Productos Lácteos de Asturias, Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Universitat de València (UV), ARTEMIS project [CGL2008-00381/CLI], LSA SAF project, and VALi+d program (FUSAT) [GV-20100270]

Subjects
Gross primary production, LEAF-AREA INDEX, CYCLOPES GLOBAL PRODUCTS, Forests, VALIDATION, SOLAR SPECTRUM, FRACTION, LAI, REFLECTANCE, [SDE]Environmental Sciences, SATELLITE MEASUREMENTS, Intercomparison, FAPAR, VEGETATION, PHOTOSYNTHETICALLY ACTIVE RADIATION, Iberian Peninsula
Abstract

International audience; The fraction of absorbed photosynthetically active radiation (FAPAR) is a key variable in productivity and carbon cycle models. The variety of available FAPAR satellite products from different space agencies leads to the necessity of assessing the existing differences between them before using into models. Discrepancies of four FAPAR products derived from MODIS, SEVIRI and MERIS (TOAVEG and MGVI algorithms), covering the Iberian Peninsula from July 2006 to June 2007 are here analyzed. The assessment is based on an intercomparison involving the spatial and temporal consistency between products and a statistical analysis across land cover types. In general, significant differences are found over the Iberian Peninsula concentrated on the temporal variation and absolute values. The MODIS and MERIS/MGVI FAPAR products clearly show the highest and lowest absolute values, respectively, along with the lowest intra-annual variation. When considering individual land cover types, the largest FAPAR disagreements among the analyzed products were found between MODIS-MERI/MGVI and MERIS/TOAVEG-MERIS/MGVI over broadleaf and needleaf forests, with discrepancies quantified by RMSE higher than 0.30 and absolute bias higher than 0.25. These discrepancies can lead to relative gross primary production differences up to 65%.

Published
2013
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4. Retrieving wheat Green Area Index during the growing season from optical time series measurements based on neural network radiative transfer inversion

Author

Gregory Duveiller, Frédéric Baret, Pierre Defourny, Marie Weiss, Earth and Life Institute [Louvain-La-Neuve] (ELI), Université Catholique de Louvain (UCL), Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Catholique de Louvain = Catholic University of Louvain (UCL), and Belgian Fond de la Recherche Scientifique FNRS

Subjects
[SPI.OTHER]Engineering Sciences [physics]/Other, Earth observation, WINTER WHEAT, MULTISITE ANALYSES, Mean squared error, VEGETATION INDEX, LEAF-AREA, SPECTRAL-BIOPHYSICAL DATA, TRANSFER MODELS, 0207 environmental engineering, CYCLOPES GLOBAL PRODUCTS, Soil Science, Growing season, 02 engineering and technology, NEURAL NETWORKS, DATA ASSIMILATION, TIME SERIES, Radiative transfer, GREEN AREA INDEX, Computers in Earth Sciences, Leaf area index, 020701 environmental engineering, Image resolution, Remote sensing, Mathematics, SPOT/HRV, Artificial neural network, Geology, Inversion (meteorology), 04 agricultural and veterinary sciences, HEMISPHERICAL PHOTOGRAPHY, SATURATION, SPOT/HRVIR, [SDE]Environmental Sciences, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, LEAF AREA INDEX, CANOPY REFLECTANCE, RADIATIVE TRANSFER INVERSION, INDICE FOLIAIRE, REMOTE-SENSING DATA
Abstract

International audience; Keywords: Winter wheat Leaf Area Index Green Area Index Radiative transfer inversion Neural networks Saturation SPOT/HRV SPOT/HRVIR Time series Technological advances have opened the possibility to have Earth observation imagery combining both high spatial resolution with high revisit frequency. The monitoring of land surface processes will greatly benefit from this type of data if biophysical variables such as Leaf Area Index (LAI) can be retrieved from it. However, the large amounts of data that will become available call for methods satisfying constraint of (i) portability across different landscapes, (ii) independence from field measurements and (iii) computational efficiency. Currently, the most suitable technique to approach this objective is neural network inversion of radiative transfer. This paper quantifies the performance of such approach for a specific crop (winter wheat) all along the growing season. By redefining the retrieved biophysical variable as Green Area Index (GAI) and correcting the typical saturation effect that affects the estimation of higher values, this study shows that physically-based retrieval can yield similar results to those obtained by empirical methods such as stepwise linear regression (with an relative RMSE of 24.7% and 22.8% respectively). The research further shows how a trained neural network for a specific sensor can produce a GAI map from imagery acquired from different viewing conditions without a significant loss in accuracy.

Published
2010
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