22 results on '"van der Tol, Christiaan"'
Search Results
2. Multi-sensor spectral synergies for crop stress detection and monitoring in the optical domain: A review
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Berger, Katja, Machwitz, Miriam, Kycko, Marlena, Kefauver, Shawn C., Van Wittenberghe, Shari, Gerhards, Max, Verrelst, Jochem, Atzberger, Clement, van der Tol, Christiaan, Damm, Alexander, Rascher, Uwe, Herrmann, Ittai, Paz, Veronica Sobejano, Fahrner, Sven, Pieruschka, Roland, Prikaziuk, Egor, Buchaillot, Ma. Luisa, Halabuk, Andrej, Celesti, Marco, Koren, Gerbrand, Gormus, Esra Tunc, Rossini, Micol, Foerster, Michael, Siegmann, Bastian, Abdelbaki, Asmaa, Tagliabue, Giulia, Hank, Tobias, Darvishzadeh, Roshanak, Aasen, Helge, Garcia, Monica, Pôças, Isabel, Bandopadhyay, Subhajit, Sulis, Mauro, Tomelleri, Enrico, Rozenstein, Offer, Filchev, Lachezar, Stancile, Gheorghe, Schlerf, Martin, Global Ecohydrology and Sustainability, Environmental Sciences, Berger, K, Machwitz, M, Kycko, M, Kefauver, S, Van Wittenberghe, S, Gerhards, M, Verrelst, J, Atzberger, C, van der Tol, C, Damm, A, Rascher, U, Herrmann, I, Paz, V, Fahrner, S, Pieruschka, R, Prikaziuk, E, Buchaillot, M, Halabuk, A, Celesti, M, Koren, G, Gormus, E, Rossini, M, Foerster, M, Siegmann, B, Abdelbaki, A, Tagliabue, G, Hank, T, Darvishzadeh, R, Aasen, H, Garcia, M, Pôças, I, Bandopadhyay, S, Sulis, M, Tomelleri, E, Rozenstein, O, Filchev, L, Stancile, G, Schlerf, M, Global Ecohydrology and Sustainability, Environmental Sciences, Department of Water Resources, Digital Society Institute, Faculty of Geo-Information Science and Earth Observation, UT-I-ITC-WCC, Department of Natural Resources, and UT-I-ITC-FORAGES
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Precision agriculture ,multispectral ,biotic and abiotic stre ,satellite ,Soil Science ,solar induced fluorescence ,Geology ,multi-modal ,Precision agriculture multi-modal solar-induced fluorescence satellite hyperspectral multispectral biotic and abiotic stress ,UNESCO::CIENCIAS TECNOLÓGICAS ,ITC-HYBRID ,hyperspectral ,ITC-ISI-JOURNAL-ARTICLE ,ddc:550 ,Computers in Earth Sciences - Abstract
Remote detection and monitoring of the vegetation responses to stress became relevant for sustainable agriculture. Ongoing developments in optical remote sensing technologies have provided tools to increase our understanding of stress-related physiological processes. Therefore, this study aimed to provide an overview of the main spectral technologies and retrieval approaches for detecting crop stress in agriculture. Firstly, we present integrated views on: i) biotic and abiotic stress factors, the phases of stress, and respective plant responses, and ii) the affected traits, appropriate spectral domains and corresponding methods for measuring traits remotely. Secondly, representative results of a systematic literature analysis are highlighted, identifying the current status and possible future trends in stress detection and monitoring. Distinct plant responses occurring under short-term, medium-term or severe chronic stress exposure can be captured with remote sensing due to specific light interaction processes, such as absorption and scattering manifested in the reflected radiance, i.e. visible (VIS), near infrared (NIR), shortwave infrared, and emitted radiance, i.e. solar-induced fluorescence and thermal infrared (TIR). From the analysis of 96 research papers, the following trends can be observed: increasing usage of satellite and unmanned aerial vehicle data in parallel with a shift in methods from simpler parametric approaches towards more advanced physically-based and hybrid models. Most study designs were largely driven by sensor availability and practical economic reasons, leading to the common usage of VIS-NIR-TIR sensor combinations. The majority of reviewed studies compared stress proxies calculated from single-source sensor domains rather than using data in a synergistic way. We identified new ways forward as guidance for improved synergistic usage of spectral domains for stress detection: (1) combined acquisition of data from multiple sensors for analysing multiple stress responses simultaneously (holistic view); (2) simultaneous retrieval of plant traits combining multi-domain radiative transfer models and machine learning methods; (3) assimilation of estimated plant traits from distinct spectral domains into integrated crop growth models. As a future outlook, we recommend combining multiple remote sensing data streams into crop model assimilation schemes to build up Digital Twins of agroecosystems, which may provide the most efficient way to detect the diversity of environmental and biotic stresses and thus enable respective management decisions.
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- 2022
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3. Downscaling of far-red solar-induced chlorophyll fluorescence of different crops from canopy to leaf level using a diurnal data set acquired by the airborne imaging spectrometer HyPlant
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Siegmann, Bastian, Cendrero-Mateo, Maria Pilar, Cogliati, Sergio, Damm, Alexander, Gamon, John, Herrera, David, Jedmowski, Christoph, Junker-Frohn, Laura Verena, Kraska, Thorsten, Muller, Onno, Rademske, Patrick, van der Tol, Christiaan, Quiros-Vargas, Juan, Yang, Peiqi, Rascher, Uwe, Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, UT-I-ITC-WCC, Siegmann, B, Cendrero-Mateo, M, Cogliati, S, Damm, A, Gamon, J, Herrera, D, Jedmowski, C, Junker-Frohn, L, Kraska, T, Muller, O, Rademske, P, van der Tol, C, Quiros-Vargas, J, Yang, P, and Rascher, U
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SIF ,FIS/06 - FISICA PER IL SISTEMA TERRA E PER IL MEZZO CIRCUMTERRESTRE ,Solar-induced chlorophyll fluorescence ,Photosynthetically active radiation ,Fluorescence correction vegetation index ,GEO/12 - OCEANOGRAFIA E FISICA DELL'ATMOSFERA ,UT-Hybrid-D ,food and beverages ,Diurnal course ,FCVI ,Article ,Fluorescence escape fraction ,ITC-HYBRID ,ITC-ISI-JOURNAL-ARTICLE ,HyPlant ,ddc:550 - Abstract
Remote sensing-based measurements of solar-induced chlorophyll fluorescence (SIF) are useful for assessing plant functioning at different spatial and temporal scales. SIF is the most direct measure of photosynthesis and is therefore considered important to advance capacity for the monitoring of gross primary production (GPP) while it has also been suggested that its yield facilitates the early detection of vegetation stress. However, due to the influence of different confounding effects, the apparent SIF signal measured at canopy level differs from the fluorescence emitted at leaf level, which makes its physiological interpretation challenging. One of these effects is the scattering of SIF emitted from leaves on its way through the canopy. The escape fraction (fesc) describes the scattering of SIF within the canopy and corresponds to the ratio of apparent SIF at canopy level to SIF at leaf level. In the present study, the fluorescence correction vegetation index (FCVI) was used to determine fesc of far-red SIF for three structurally different crops (sugar beet, winter wheat, and fruit trees) from a diurnal data set recorded by the airborne imaging spectrometer HyPlant. This unique data set, for the first time, allowed a joint analysis of spatial and temporal dynamics of structural effects and thus the downscaling of far-red SIF from canopy (SIF760canopy) to leaf level (SIF760leaf). For a homogeneous crop such as winter wheat, it seems to be sufficient to determine fesc once a day to reliably scale SIF760 from canopy to leaf level. In contrast, for more complex canopies such as fruit trees, calculating fesc for each observation time throughout the day is strongly recommended. The compensation for structural effects, in combination with normalizing SIF760 to remove the effect of incoming radiation, further allowed the estimation of SIF emission efficiency (εSIF) at leaf level, a parameter directly related to the diurnal variations of plant photosynthetic efficiency., Highlights • The far-red SIF (SIF760) escape fraction (fesc) strongly depends on the crop type • Crops with complex canopy geometries show more spatio-temporal variability in fesc • Detection of diurnal variations in plant physiology from airborne SIF760 maps
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- 2021
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4. Global transpiration data from sap flow measurements: the SAPFLUXNET database
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Poyatos, Rafael, Granda, Victor, Flo, Victor, Adams, Mark A., Adorjan, Balazs, Aguade, David, Aidar, Marcos P. M., Allen, Scott, Susana Alvarado-Barrientos, M., Anderson-Teixeira, Kristina J., Aparecido, Luiza Maria, Arain, M. Altaf, Aranda, Ismael, Asbjornsen, Heidi, Baxter, Robert, Beamesderfer, Eric, Berry, Z. Carter, Berveiller, Daniel, Blakely, Bethany, Boggs, Johnny, Bohrer, Gil, Bolstad, Paul, Bonal, Damien, Bracho, Rosvel, Brito, Patricia, Brodeur, Jason, Chave, Jerome, Chen, Hui, Cisneros, Cesar, Clark, Kenneth, Cremonese, Edoardo, Dang, Hongzhong, David, Jorge S., David, Teresa S., Delpierre, Nicolas, Desai, Ankur R., Do, Frederic C., Dohnal, Michal, Domec, Jean-Christophe, Dzikiti, Sebinasi, Edgar, Colin, Eichstaedt, Rebekka, El-Madany, Tarek S., Elbers, Jan, Eller, Cleiton B., Euskirchen, Eugenie S., Ewers, Brent, Fonti, Patrick, Forner, Alicia, Forrester, David, Freitas, Helber C., Galvagno, Marta, Garcia-Tejera, Omar, Ghimire, Chandra Prasad, Gimeno, Teresa E., Grace, John, Granier, Andre, Griebel, Anne, Guangyu, Yan, Hanson, Paul J., Hasselquist, Niles, Heinrich, Ingo, Hernandez-Santana, Virginia, Herrmann, Valentine, Holtta, Teemu, Holwerda, Friso, Irvine, James, Ayutthaya, Supat Isarangkool Na, Jarvis, Paul G., Jochheim, Hubert, Joly, Carlos A., Kaplick, Julia, Kim, Hyun Seok, Klemedtsson, Leif, Kropp, Heather, Lagergren, Fredrik, Lane, Patrick, Lapenas, Andrei, Lechuga, Victor, Lee, Minsu, Leuschner, Christoph, Limousin, Jean-Marc, Linares, Juan Carlos, Linderson, Maj-Lena, Lindroth, Anders, Llorens, Pilar, Lopez-Bernal, Alvaro, Loranty, Michael M., Luttschwager, Dietmar, Macinnis-Ng, Cate, Marechaux, Isabelle, Martin, Timothy A., Matheny, Ashley, McDowell, Nate, McMahon, Sean, Meir, Patrick, Meszaros, Ilona, Migliavacca, Mirco, Mitchell, Patrick, Molder, Meelis, Montagnani, Leonardo, Moore, Georgianne W., Nakada, Ryogo, Niu, Furong, Nolan, Rachael H., Norby, Richard, Novick, Kimberly, Oberhuber, Walter, Obojes, Nikolaus, Oishi, A. Christopher, Oliveira, Rafael S., Oren, Ram, Ourcival, Jean-Marc, Paljakka, Teemu, Perez-Priego, Oscar, Peri, Pablo L., Peters, Richard L., Pfautsch, Sebastian, Pockman, William T., Preisler, Yakir, Rascher, Katherine, Robinson, George, Rocha, Humberto, Rocheteau, Alain, Roll, Alexander, Rosado, Bruno H. P., Rowland, Lucy, Rubtsov, Alexey, Sabate, Santiago, Salmon, Yann, Salomon, Roberto L., Sanchez-Costa, Elisenda, Schuldt, Bernhard, Shashkin, Alexandr, Stahl, Clement, Stojanovic, Marko, Sun, Ge, Szatniewska, Justyna, Tatarinov, Fyodor, Tesar, Miroslav, Thomas, Frank M., Tor-ngern, Pantana, Urban, Josef, Valladares, Fernando, van der Tol, Christiaan, van Meerveld, Ilja, Varlagin, Andrej, Voigt, Holm, Warren, Jeffrey, Werner, Christiane, Werner, Willy, Wingate, Lisa, Wullschleger, Stan, Yi, Koong, Zweifel, Roman, Steppe, Kathy, Mencuccini, Maurizio, and Martinez-Vilalta, Jordi
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Ecology ,Botany - Abstract
Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.
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- 2021
5. On the relationship between sub-daily instantaneous and daily total gross primary production: Implications for interpreting satellite-based SIF retrievals
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Zhang, Yao, Xiao, X, Zhang, Yongguang, Wolf, Sebastian, Zhou, Sha, Joiner, Joanna, Guanter, Luis, Verma, Manish, Sun, Ying, Yang, Xi, Paul-Limoges, Eugénie, Gough, Christopher M, Wohlfahrt, Georg, Gioli, Beniamino, van der Tol, Christiaan, Yann, Nouvellon, Lund, Magnus, and de Grandcourt, Agnès
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Diurnal variation ,Light use efficiency ,Correction factor ,Geomatic Engineering ,Phenology ,SCOPE ,Photosynthetically active radiation ,FluxCom ,FLUXNET ,Geological & Geomatics Engineering ,Physical Geography and Environmental Geoscience - Abstract
Spatially and temporally continuous estimation of plant photosynthetic carbon fixation (or gross primary production, GPP) is crucial to our understanding of the global carbon cycle and the impact of climate change. Besides spatial, seasonal and interannual variations, GPP also exhibits strong diurnal variations. Satellite retrieved solar-induced chlorophyll fluorescence (SIF) provides a spatially continuous, but temporally discrete measurement of plant photosynthesis, and has the potential to be used to estimate GPP at global scale. However, it remains unclear whether the seasonal time series of SIF snapshots taken at a fixed time of the day can be used to infer daily total GPP variation at spatial and seasonal scales. In this study, we first used GPP estimates from 135 eddy covariance flux sites, covering a wide range of geographic locations and biome types, to investigate the relationship between the instantaneous GPP (GPPᵢₙₛₜ) and daily GPP (GPPdₐᵢₗy) on the seasonal course for different times of the day. Latitudinal and diurnal patterns were found to correspond to variations in photosynthetically active radiation (PAR) and light use efficiency (LUE), respectively. We then used the Soil-Canopy Observation Photosynthesis and Energy Balance (SCOPE) model and the FluxCom GPP product to investigate the instantaneous and daily SIF-GPP relationships at five flux tower sites along a latitudinal gradient and at a global scale for different biome types. The results showed that daily SIF had a stronger linear correlation with daily GPP than instantaneous SIF at the seasonal scale, with an instantaneous to daily SIF conversion factor following the latitudinal and seasonal pattern driven by PAR. Our study highlights the necessity to take the latitudinal and diurnal factors into consideration for SIF-GPP relationship analyses or for physiological phenology analyses based on SIF.
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- 2018
6. Nutrient induced changes in Sun-Induced Fluorescence emission in a Mediterranean grassland
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Martini, David, Pacheco-Labrador, Javier, Perez-Priego, Oscar, Van Der Tol, Christiaan, El Madany, Tarek, Julitta, Tommaso, Rossini, Micol, Gitelson, Anatoly, Reichstein, Markus, and Migliavacca, Mirco
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Sun-Induced Fluorescence, Fesc, Nutrient Fertilization - Abstract
Sun induced fluorescence (SIF), the radiation flux emitted by plant chlorophylls molecules in the 650-800 nm spectral window, is considered an indicator of photosynthetic performance. Recently it has been shown that SIF can track changes in light use efficiency (LUE), and therefore it is a good predictor of gross primary production (GPP) at various scales, from leaves and ecosystem to regional and global scale. Although SIF has been successfully used to predict GPP in various ecosystems, the mechanistic link between GPP and SIF remains not fully understood, and especially the effect of function and structure on SIF at the canopy scale remains an active area of research. SIF is emitted by the whole canopy, but only a fraction of the total emission is observed with remote sensing techniques. The escape probability of SIF (Fesc) controls the amount of SIF scattered by the canopy and is integral to separate the effect of canopy structure and function on the fluorescence signal. In this contribution we make use of data collected at the research site Majadas del Tietar, a Mediterranean grassland manipulated with Nitrogen and Phosphorus. Using the SCOPE model (Soil Canopy Observation Photochemistry and Energy fluxes) we obtain Fesc and we analyse how Top of canopy SIF and emitted SIF vary in response to the fertilization. With a combination of processes-based modelling and data driven analysis, such as relative importance analysis and structural equation modelling, we unravel the processes and causal relationship that are at the base of the GPP - SIF relationship. We show that the nutrient fertilization had an effect on plant composition, and therefore canopy structure, but also plant functioning. Nitrogen induced changes in biodiversity mainly affect leaf angle distribution of the canopy and therefore scattering properties such as Fesc. The nitrogen fertilization is also responsible for a change in plant functioning, with altered SIF emission. The simultaneous change of both canopy and structure causes the fertilization effect to be visible mainly at the emission level, but not at top of canopy, as the variation in canopy structure masks the change observed at leaf level. This contribution advances the knowledge of the highly complex dynamics involved in the GPP-SIF relationship. In depth understanding of the mechanistic processes is required to fully take advantage of the increasingly prevalent SIF data streams.
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- 2018
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7. Characterization of a highly biodiverse floodplain meadow using hyperspectral remote sensing within a plant functional trait framework
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Punalekar, Survarna, Verhoef, Anne, Tatarenko, Irina V., van der Tol, Christiaan, Macdonald, David M.J., Marchant, Benjamin, Gerard, France, White, Kevin, Gowing, David, Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, and UT-I-ITC-WCC
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optical functional types ,ITC-ISI-JOURNAL-ARTICLE ,MG4 community ,lcsh:Q ,radiative transfer model ,sedge and rush ,biophysical parameters ,lcsh:Science ,ITC-GOLD ,METIS-315824 ,field spectroscopy ,Ecology and Environment - Abstract
We assessed the potential for using optical functional types as effective markers to monitor changes in vegetation in floodplain meadows associated with changes in their local environment. Floodplain meadows are challenging ecosystems for monitoring and conservation because of their highly biodiverse nature. Our aim was to understand and explain spectral differences among key members of floodplain meadows and also characterize differences with respect to functional traits. The study was conducted on a typical floodplain meadow in UK (MG4-type, mesotrophic grassland type 4, according to British National Vegetation Classification). We compared two approaches to characterize floodplain communities using field spectroscopy. The first approach was sub-community based, in which we collected spectral signatures for species groupings indicating two distinct eco-hydrological conditions (dry and wet soil indicator species). The other approach was\ud “species-specific”, in which we focused on the spectral reflectance of three key species found on the meadow. One herb species is a typical member of the MG4 floodplain meadow community, while the other two species, sedge and rush, represent wetland vegetation. We also monitored vegetation biophysical and functional properties as well as soil nutrients and ground water levels. We found that the vegetation classes representing meadow sub-communities could not be spectrally distinguished from each other, whereas the individual herb species was found to have a distinctly different spectral signature from the sedge and rush species. The spectral differences between these three species could be explained by their observed differences in plant biophysical parameters, as corroborated through radiative transfer model simulations. These parameters, such as leaf area index, leaf dry matter content, leaf water content, and specific leaf area, along with other functional parameters, such as maximum carboxylation capacity and leaf nitrogen content, also helped explain the species’ differences in functional dynamics. Groundwater level and soil nitrogen availability, which are important factors governing plant nutrient status, were also found to be significantly different for the herb/wetland species’ locations. The study concludes that spectrally distinguishable species, typical for a highly biodiverse site such as a floodplain meadow, could potentially be used as target species to monitor vegetation dynamics under changing environmental conditions.
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- 2016
8. Towards an improved mapping of evapotranspiration in semi-arid regions
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Gökmen, Mustafa, van der Tol, Christiaan, Vekerdy, Zoltán, Verhoef, Wouter, Batelaan, Okke, Sarikaya, Hasan Z., Neale, C.M.U., Cosh, M.H., Faculty of Geo-Information Science and Earth Observation, Department of Water Resources, and UT-I-ITC-WCC
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In drylands, evapotranspiration is mainly limited by soil moisture, but current surface energy balance models do not directly make use of this fact. We tested the single-source energy balance model SEBS in a semi-arid region and showed that SEBS is significantly overestimating the evaporative fraction for sparsely vegetated drylands. As an alternative for such conditions, we derived an empirical function of soil moisture, temperature gradient and NDVI, which performed significantly better. This was then integrated with the evaporative fraction output of SEBS for an improved mapping of evapotranspiration in a semi-arid region. Ground measurements of the evaporative fraction from five Bowen ratio energy balance systems were used first to test SEBS and then to calibrate the empirical equation. The resulting method uses remote sensing data and in situ air temperature measurement.
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- 2012
9. Plant productivity and evaporation from remote sensing
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Prikaziuk, E., van der Tol, Christiaan, Department of Water Resources, UT-I-ITC-WCC, and Faculty of Geo-Information Science and Earth Observation
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The quantification of carbon and water fluxes between the land surface and the atmosphere has practical applications in agriculture and it is fundamental for global monitoring, especially in view of climate change. The main process of carbon uptake is photosynthesis, and the main water flux from the land to the atmosphere is evaporation, where we can differentiate transpiration as the flux through pores of living organisms, mostly stomata in plants. Remote sensing products can be used for both photosynthesis and evapotranspiration fluxes estimates, but modelling is an inevitable step. This thesis assesses the Soil-Canopy-Observation of Photosynthesis and Energy fluxes (SCOPE) model for flux simulation in theory, in agricultural field experiments, and globally for different ecosystems. Global sensitivity analysis In the first step a global sensitivity analysis (GSA) of SCOPE was carried out to evaluate the theoretical capability of the model to be driven by satellite data, and the effects of the atmosphere on this capability. The innovative element of the study was the sensitivity analysis at satellite level, including the atmosphere. Previous GSAs of SCOPE were limited to top of canopy (or bottom of atmosphere) level. The need for atmospheric analysis was also dictated by the choice of the Sentinel-3 satellite, the data of which were only available at the top of atmosphere level then. Another innovation - and also the motivation for the use of Sentinel-3 - was the GSA in thermal infrared domain (TIR). Previous studies demonstrated and our study confirmed that the link between thermal radiance emission and the key determinant of photosynthesis rate (plant biochemical property of the CO2 assimilating enzyme Rubisco; maximum Rubisco carboxylation capacity, Vcmax) is apparent in the output of the SCOPE model. We did not succeed in retrieving Vcmax from TIR radiance with numerical optimization, but it definitely requires further investigation. Large scale study The following step was the global evaluation of SCOPE-simulated gross primary productivity (GPP) and evapotranspiration (ET) across herbaceous and woody plant functional types in Europe. Various seasonally static and dynamic values of Vcmax were evaluated. Surprisingly, for most of the studied ecosystems the default parametrization performed the best for the GPP flux. The largest errors were found in dry regions, which we attribute to the lack of a soil water balance computation and soil moisture-transpiration feedback in SCOPE model. Another source of uncertainty was the varying ground pixel position of Sentinel-3, inherent from the varying observation orbit. A separate chapter in the thesis discusses the constraints on the homogeneity of the area of interest in the application of time series of Sentinel-3. Local scale study The final step was the in-field application of SCOPE for retrieval from hyperspectral data and potato plant productivity simulation from the CO2 assimilation flux. The performance of the retrieval algorithm was not as successful as on the synthetic dataset, in particular only leaf chlorophyll content (Cab) and leaf area index (LAI) were retrieved with acceptable accuracy. At the same time, exactly those two parameters are the main drivers of photosynthesis, therefore the retrieval of LAI and Cab enabled us to model potato yield as the sum of mean daily net primary productivity (NPP) fluxes corrected with the harvest index. Future perspectives This thesis confirms that SCOPE can be applied not only as a radiative transfer model, as it mostly has been applied up to now, but also as photosynthesis and energy balance model. SCOPE provides physically consistent approach where the satellite reflectance input and traits and fluxes output occur within a single model. The release of the faster version 2.0 facilitates operational applications further. The future improvement of the SCOPE model might include (1) a soil water balance representation relevant for drought-subjected ecosystems, where ET is determined by water availability, rather than energy availability, and (2) leaf clumping relevant for forests and row crops, whose leaves form patches in contrast to grasses, where leaves are evenly distributed. Finally, the link between thermal emitted radiance and Vcmax should be investigated in the coming research.
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- 2021
10. senSCOPE: Modeling mixed canopies combining green and brown senesced leaves. Evaluation in a Mediterranean Grassland
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Gerardo Moreno, Tarek S. El-Madany, Markus Reichstein, Rosario Gonzalez-Cascon, Javier Pacheco-Labrador, Jin-Hong Guan, M. Pilar Martín, Christiaan van der Tol, Oscar Perez-Priego, Mirco Migliavacca, Arnaud Carrara, Federal Ministry for Economics Affairs and Energy (Germany), German Centre for Air and Space Travel, Ministerio de Economía y Competitividad (España), European Commission, El-Madany, Tarek S., van der Tol, Christiaan, Martin, M. Pilar, Gonzalez-Cascón, Rosario, Perez-Priego, Oscar, Moreno, Gerardo, Carrara, Arnaud, Reichstein, Markus, Migliavacca, Mirco, Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, and UT-I-ITC-WCC
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Chlorophyll ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Soil Science ,02 engineering and technology ,Atmospheric sciences ,01 natural sciences ,chemistry.chemical_compound ,SCOPE ,Radiative transfer ,Plant functional traits ,Computers in Earth Sciences ,Leaf area index ,Photosynthesis ,0105 earth and related environmental sciences ,Remote sensing ,Mathematics ,Transpiration ,Senesced leaves ,Primary production ,Geology ,Vegetation ,Grassland ,020801 environmental engineering ,SenSCOPE ,chemistry ,Hyperspectral ,Photosynthetically active radiation ,Sun-induced fluorescence ,ITC-ISI-JOURNAL-ARTICLE ,Radiance ,GPP - Abstract
18 Pág. Departamento de Medio Ambiente y Agronomía, The coupling of radiative transfer, energy balance, and photosynthesis models has brought new opportunities to characterize vegetation functional properties from space. However, these models do not accurately represent processes in ecosystems characterized by mixtures of green vegetation and senescent plant material (SPM), in particular grasslands. These inaccuracies limit the retrieval of vegetation biophysical and functional properties. Green and senesced plants feature contrasting spectral properties and carry out different functions that current coupled models do not represent separately. Besides, senescent pigments' absorption features change as SPM decomposes, and neither is this process well parameterized in radiative transfer models. This manuscript aims at overcoming these limitations. On the one hand, we have developed senSCOPE, a version of the Soil-Canopy Observation of Photosynthesis and Energy fluxes (SCOPE) that separately represents light interaction and physiology of green and senesced leaves. On the other, we have characterized new specific absorption coefficients of senescent pigments (Ks) from optical measurements of SPM from a Mediterranean grassland. Sensitivity analyses revealed that compared to SCOPE, senSCOPE 1) predicts variables that respond more linearly to the faction of green leaf area; and 2) keeps high levels of absorbed photosynthetically active radiation in the green leaves, which leads to significant differences in leaf photosynthesis, non-photochemical quenching, and transpiration. Moreover, we compared SCOPE vs. senSCOPE's capability to provide estimates of functional and biophysical parameters of vegetation. We assimilated different combinations of reflectance factors (R), chlorophyll sun-induced fluorescence radiance in the O2-A band (F760), gross primary production (GPP), and thermal radiance (Lt) measured in a Mediterranean grassland. Besides, we compared the role of three different sets of Ks coefficients in the inversion of senSCOPE, two estimated from SPM. The performance of the inversions was assessed using field data and a pattern-oriented model evaluation approach. Unlike SCOPE, senSCOPE provided unbiased estimates of chlorophyll content (Cab) during the dry season. The use of SPM-specific Ks improved the representation of R in the near-infrared wavelengths; and, consequently, the estimation of leaf area index (LAI). Compared with field LAI, the coefficient of determination R2 increased from ~0.4 to ~0.6, depending on the inversion constraints. Compared with SCOPE, the new model and coefficients together reduced the root mean squared error between observed and modeled R (~40%), F760 (~30%), and GPP (~5%). Both models failed to represent Lt; in this case, senSCOPE featured larger uncertainties. The modeling approach we propose improves the simulation and retrieval of vegetation properties and function in grasslands. Further work is needed to test the applicability of senSCOPE in different ecosystems, improve the simulation of the thermal spectral domain, and better characterize the optical parameters of SPM. To do so, new databases of SPM optical and biophysical properties should be produced., JPL, MM and MR acknowledge the EnMAP project MoReDEHESHyReS “Modelling Responses of Dehesas with Hyperspectral Remote Sensing” (Contract No. 50EE1621, German Aerospace Center (DLR) and the German Federal Ministry of Economic Affairs and Energy). Authors acknowledge the Alexander von Humboldt Foundation for supporting this research with the Max-Planck Prize to Markus Reichstein; the project SynerTGE “Landsat-8+Sentinel-2: exploring sensor synergies for monitoring and modeling key vegetation biophysical variables in tree-grass ecosystems” (CGL2015-69095-R, MINECO/FEDER,UE); and the project FLUχPEC “Monitoring changes in water and carbon fluxes from remote and proximal sensing in Mediterranean ‘dehesa’ ecosystem” (CGL2012-34383, Spanish Ministry of Economy and Competitiveness).
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- 2021
11. Modelling sun-induced fluorescence and photosynthesis with a land surface model at local and regional scales in northern Europe
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Philipp Köhler, Federico Magnani, Annalea Lohila, Pasi Kolari, Mika Aurela, Tea Thum, Luis Guanter, Tuomas Laurila, Tuula Aalto, Christiaan van der Tol, Sönke Zaehle, Tiina Markkanen, Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, UT-I-ITC-WCC, Department of Physics, Micrometeorology and biogeochemical cycles, Thum, Tea, Zaehle, Sönke, Köhler, Philipp, Aalto, Tuula, Aurela, Mika, Guanter, Lui, Kolari, Pasi, Laurila, Tuoma, Lohila, Annalea, Magnani, Federico, Van Der Tol, Christiaan, and Markkanen, Tiina
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,EDDY COVARIANCE ,Eddy covariance ,lcsh:Life ,DATA ASSIMILATION SYSTEM ,FLUX MEASUREMENTS ,SCOTS PINE FOREST ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,114 Physical sciences ,CO2 EXCHANGE ,PHOTOSYSTEM-II ,lcsh:QH540-549.5 ,medicine ,Satellite imagery ,Chlorophyll fluorescence ,Ecology, Evolution, Behavior and Systematics ,1172 Environmental sciences ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Remote sensing ,4112 Forestry ,Simulation modeling ,lcsh:QE1-996.5 ,Primary production ,BOREAL CONIFEROUS FOREST ,BIOCHEMICAL-MODEL ,Seasonality ,medicine.disease ,Ecology, Evolution, Behavior and Systematic ,TERRESTRIAL CHLOROPHYLL FLUORESCENCE ,lcsh:Geology ,lcsh:QH501-531 ,Photosynthetically active radiation ,13. Climate action ,ITC-ISI-JOURNAL-ARTICLE ,Environmental science ,ENERGY-BALANCE ,lcsh:Ecology ,ITC-GOLD ,010606 plant biology & botany - Abstract
Recent satellite observations of sun-induced chlorophyll fluorescence (SIF) are thought to provide a large-scale proxy for gross primary production (GPP), thus providing a new way to assess the performance of land surface models (LSMs). In this study, we assessed how well SIF is able to predict GPP in the Fenno-Scandinavian region and what potential limitations for its application exist. We implemented a SIF model into the JSBACH LSM and used active leaf-level chlorophyll fluorescence measurements (Chl F) to evaluate the performance of the SIF module at a coniferous forest at Hyytiälä, Finland. We also compared simulated GPP and SIF at four Finnish micrometeorological flux measurement sites to observed GPP as well as to satellite-observed SIF. Finally, we conducted a regional model simulation for the Fenno-Scandinavian region with JSBACH and compared the results to SIF retrievals from the GOME-2 (Global Ozone Monitoring Experiment-2) space-borne spectrometer and to observation-based regional GPP estimates. Both observations and simulations revealed that SIF can be used to estimate GPP at both site and regional scales. At regional scale the model was able to simulate observed SIF averaged over 5 years with r2 of 0.86. The GOME-2-based SIF was a better proxy for GPP than the remotely sensed fAPAR (fraction of absorbed photosynthetic active radiation by vegetation). The observed SIF captured the seasonality of the photosynthesis at site scale and showed feasibility for use in improving of model seasonality at site and regional scale.
- Published
- 2017
12. Evaluating the predictive power of sun-induced chlorophyll fluorescence to estimate net photosynthesis of vegetation canopies: A SCOPE modeling study
- Author
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Neus Sabater, Federico Magnani, Gina H. Mohammed, Jochem Verrelst, Juan Pablo Rivera, Jose Moreno, Christiaan van der Tol, Department of Water Resources, Faculty of Geo-Information Science and Earth Observation, UT-I-ITC-WCC, Verrelst, Jochem, van der Tol, Christiaan, Magnani, Federico, Sabater, Neu, Rivera, Juan Pablo, Mohammed, Gina, and Moreno, Jose
- Subjects
Canopy ,010504 meteorology & atmospheric sciences ,Band analysi ,0211 other engineering and technologies ,Soil Science ,02 engineering and technology ,01 natural sciences ,chemistry.chemical_compound ,Photosynthesi ,SCOPE ,Emission spectrum ,Computers in Earth Sciences ,Leaf area index ,METIS-315823 ,Chlorophyll fluorescence ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Remote sensing ,Geology ,22/4 OA procedure ,Photosynthetic capacity ,Regression ,FLEX ,Imaging spectroscopy ,chemistry ,Sun-induced fluorescence ,ITC-ISI-JOURNAL-ARTICLE ,Chlorophyll ,Environmental science ,Nonlinear regression - Abstract
Progress in imaging spectroscopy technology and data processing can enable derivation of the complete sun-induced chlorophyll fluorescence (SIF) emission spectrum. This opens up opportunities to fully exploit the use of the SIF spectrum as an indicator of photosynthetic activity. Simulations performed with the coupled fluorescence–photosynthesis model SCOPE were used to determine how strongly canopy-leaving SIF can be related to net photosynthesis of the canopy (NPC) for various canopy configurations. Regression analysis between SIF retrievals and NPC values produced the following general findings: (1) individual SIF bands that were most sensitive to NPC were located around the first emission peak (SIFred) for heterogeneous canopy configurations (i.e., varying biochemistry, leaf, canopy variables); (2) using two SIF retrieval bands, e.g. O2-B at 687 nm and O2-A at 760 nm, or the red and NIR emission peaks at 685 nm and 740 nm, led to stronger correlations than using only one band; (3) using the O2-B and the O2-A SIF retrieval bands was at least as effective as using the two emission peaks; (4) superior correlations were achieved by using the four main SIF retrieval bands (Hα, O2-B, water vapor, O2-A); and (5) further improvements may be obtained by exploiting the full SIF profile and by using an adaptive, nonlinear regression algorithm such as Gaussian processes regression (GPR). Relationships can be due to variation in photosynthetic capacity (Vcmo), but also from variation in leaf optical and canopy structural variables such as chlorophyll content and leaf area index. Overall, modeling results suggest that sampling the SIF profile in at least both O2-B and O2-A bands enables quantification photosynthetic activity of vegetation with high accuracy.
- Published
- 2016
- Full Text
- View/download PDF
13. Effects of long-term changes in forest canopy structure on rainfall interception loss
- Author
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César Ramiro, Cisneros Vaca, Verhoef (Emeritus), Wouter, van der Tol, Christiaan, Department of Water Resources, UT-I-ITC-WCC, and Faculty of Geo-Information Science and Earth Observation
- Subjects
Tree canopy ,Environmental science ,Interception ,ITC-GOLD ,Atmospheric sciences ,Term (time) - Published
- 2018
- Full Text
- View/download PDF
14. 'Exploring fluorescence and pigment reflectance as methods to estimate photosynthesis with remote sensors
- Author
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Nastassia Rajh Vilfan, Verhoef (Emeritus), Wouter, van der Tol, Christiaan, Department of Water Resources, UT-I-ITC-WCC, and Faculty of Geo-Information Science and Earth Observation
- Subjects
Pigment ,Materials science ,visual_art ,visual_art.visual_art_medium ,Remote sensors ,Photosynthesis ,Reflectivity ,Fluorescence ,Remote sensing - Published
- 2018
- Full Text
- View/download PDF
15. Interpretation of Sun-Induced Chlorophyll Fluorescence for Remote Sensing of Photosynthesis
- Author
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Peiqi Yang, Verhoef (Emeritus), Wouter, van der Tol, Christiaan, UT-I-ITC-WCC, Faculty of Geo-Information Science and Earth Observation, and ITC-WRS
- Subjects
Remote sensing (archaeology) ,Environmental science ,Photosynthesis ,ITC-GOLD ,Chlorophyll fluorescence ,Remote sensing ,Interpretation (model theory) - Published
- 2018
16. Quantitative Remote Sensing of Vegetation Properties and Functioning under Normal and Dry Conditions
- Author
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Bagher Bayat, Verhoef (Emeritus), Wouter, van der Tol, Christiaan, Department of Water Resources, UT-I-ITC-WCC, and Faculty of Geo-Information Science and Earth Observation
- Subjects
Remote sensing (archaeology) ,medicine ,Environmental science ,medicine.symptom ,Vegetation (pathology) ,Remote sensing - Published
- 2018
17. How climate and land use determine the hydrology of Lake Naivasha Basin
- Author
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Vincent Odongo, Su, Bob, van der Tol, Christiaan, and Department of Water Resources
- Subjects
ITC-GOLD - Published
- 2016
- Full Text
- View/download PDF
18. Simulating energy, water and CO2 fluxes at representative desert ecosystems over Central Asia
- Author
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Li, Longhui, Su, Bob, van der Tol, Christiaan, Faculty of Geo-Information Science and Earth Observation, Department of Water Resources, and University of Twente
- Published
- 2015
19. Modeling of forest above-ground biomass and evapotransportation dynamics
- Author
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Xin Tian, Su, Bob, van der Tol, Christiaan, and Department of Water Resources
- Subjects
Above ground ,METIS-314331 ,Evapotranspiration ,Environmental science ,Biomass ,Atmospheric sciences - Published
- 2015
- Full Text
- View/download PDF
20. Global sensitivity analysis of the A-SCOPE model in support of future FLEX fluorescence retrievals
- Author
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Jochem Verrelst, Gina H. Mohammed, Federico Magnani, Juan Pablo Rivera, Jose Moreno, Christiaan van der Tol, Verrelst, Jochem, Rivera, Juan Pablo, Van Der Tol, Christiaan, Magnani, Federico, Mohammed, Gina, and Moreno, Jose
- Subjects
Scope (project management) ,Computer science ,business.industry ,Hyperspectral imaging ,Set (abstract data type) ,FLEX ,Variable (computer science) ,global sensitivity analysi ,Signal Processing ,Sensitivity (control systems) ,fluorescence ,Leaf area index ,business ,A-SCOPE ,Graphical user interface ,Remote sensing - Abstract
In support of ESA's Earth Explorer 8 candidate mission FLEX (FLuorescence EXplorer), a Photosynthesis Study has been initiated to quantitatively link fluorescence to photosynthesis. This led to the development of A-SCOPE, a graphical user interface software package that integrates multiple biochemical models into the soil-vegetation-atmosphere-transfer model SCOPE. Its latest version (v1.53) has been successfully verified and was subsequently evaluated through a global sensitivity analysis. By using the method of Saltelli [4], the relative importance of each input variable to model outputs was quantified through first order and total effect sensitivity indices. Variations in leaf area index (LAI) and chlorophyll content are mostly impacting the reflectance and fluorescence signal. Non-driving variables that can be safely set to default values have been identified and will facilitate consolidating SCOPE into an operational and invertible model.
- Published
- 2014
21. Sensitivity of scope modelled GPP and fluorescence for different plant functional types
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Federico Magnani, Gina H. Mohammed, Wout Verhoef, Christiaan van der Tol, Jochem Verrelst, J. Moreno, Joseph A. Berry, Van Der Tol, Christiaan, Verhoef, Wout, Verrelst, Jochem, Magnani, Federico, Mohammed, Gina, Moreno, Jose, and Berry, Joe
- Subjects
Hydrology ,Irradiance ,Tropics ,Humidity ,Primary production ,sensitivity analysi ,Atmospheric sciences ,Photosynthesis ,gross primary production ,Tundra ,SCOPE ,Signal Processing ,Temperate climate ,Environmental science ,fluorescence ,plant functional type ,Tropical rainforest - Abstract
This study addresses the question which factors are responsible for reported positive correlations between solar induced fluorescence (SIF) and gross primary production (GPP). A sensitivity analysis of the model SCOPE, which simulates photosynthesis, fluorescence emission and radiative transfer in canopies, has been carried out for four different plant functional types (PFT): tropical rainforest, C4 crops, C3 crops, and tundra, located in distinct climate zones: tropical everwet (Af), tropical with seasonal drought (savannah, Aw), temperate (Cf), and continental tundra (Dfd). Literature values for structural and physiological parameters and climate reanalysis data were used as input. The effect of main driving variables points towards a positive relation between GPP and SIF. For all four climates, the partial derivative of SIF to GPP is higher when irradiance varies than when any other parameter varies. Climate and PFT specific differences occurred, including a hot-spot effect on SIF in the tropics, relatively strong sensitivity of SIF and GPP to carboxylation capacity in the tropics, and a temperature and humidity effect in the tropical seasonal climate.
- Published
- 2014
22. Coupling optical and thermal directional radiative transfer to biophysical processes in vegetated canopies
- Author
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Timmermans, J., Su, Bob, Verhoef (Emeritus), Wouter, van der Tol, Christiaan, Department of Water Resources, UT-I-ITC-WCC, and Faculty of Geo-Information Science and Earth Observation
- Published
- 2011
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