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37 results on '"Rascher, Uwe"'

7. Multi-sensor spectral synergies for crop stress detection and monitoring in the optical domain: A review

Author

Berger, Katja, primary, Machwitz, Miriam, additional, Kycko, Marlena, additional, Kefauver, Shawn C., additional, Van Wittenberghe, Shari, additional, Gerhards, Max, additional, Verrelst, Jochem, additional, Atzberger, Clement, additional, van der Tol, Christiaan, additional, Damm, Alexander, additional, Rascher, Uwe, additional, Herrmann, Ittai, additional, Paz, Veronica Sobejano, additional, Fahrner, Sven, additional, Pieruschka, Roland, additional, Prikaziuk, Egor, additional, Buchaillot, Ma. Luisa, additional, Halabuk, Andrej, additional, Celesti, Marco, additional, Koren, Gerbrand, additional, Gormus, Esra Tunc, additional, Rossini, Micol, additional, Foerster, Michael, additional, Siegmann, Bastian, additional, Abdelbaki, Asmaa, additional, Tagliabue, Giulia, additional, Hank, Tobias, additional, Darvishzadeh, Roshanak, additional, Aasen, Helge, additional, Garcia, Monica, additional, Pôças, Isabel, additional, Bandopadhyay, Subhajit, additional, Sulis, Mauro, additional, Tomelleri, Enrico, additional, Rozenstein, Offer, additional, Filchev, Lachezar, additional, Stancile, Gheorghe, additional, and Schlerf, Martin, additional

Published
2022
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10. Multi-sensor spectral synergies for crop stress detection and monitoring in the optical domain: A review

Author

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, 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, 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, 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, and Schlerf, Martin

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 analys

Published
2022

11. Towards consistent assessments of in situ radiometric measurements for the validation of fluorescence satellite missions

Author

Buman, B, Hueni, A, Colombo, R, Cogliati, S, Celesti, M, Julitta, T, Burkart, A, Siegmann, B, Rascher, U, Drusch, M, Damm, A, Buman, Bastian, Hueni, Andreas, Colombo, Roberto, Cogliati, Sergio, Celesti, Marco, Julitta, Tommaso, Burkart, Andreas, Siegmann, Bastian, Rascher, Uwe, Drusch, Matthias, Damm, Alexander, Buman, B, Hueni, A, Colombo, R, Cogliati, S, Celesti, M, Julitta, T, Burkart, A, Siegmann, B, Rascher, U, Drusch, M, Damm, A, Buman, Bastian, Hueni, Andreas, Colombo, Roberto, Cogliati, Sergio, Celesti, Marco, Julitta, Tommaso, Burkart, Andreas, Siegmann, Bastian, Rascher, Uwe, Drusch, Matthias, and Damm, Alexander

Abstract

The upcoming Fluorescence Explorer (FLEX) satellite mission aims to provide high quality radiometric measurements for subsequent retrieval of sun-induced chlorophyll fluorescence (SIF). The combination of SIF with other observations stemming from the FLEX/Sentinel-3 tandem mission holds the potential to assess complex ecosystem processes. The calibration and validation (cal/val) of these radiometric measurements and derived products are central but challenging components of the mission. This contribution outlines strategies for the assessment of in situ radiometric measurements and retrieved SIF. We demonstrate how in situ spectrometer measurements can be analysed in terms of radiometric, spectral and spatial uncertainties. The analysis of more than 200 k spectra yields an average bias between two radiometric measurements by two individual spectrometers of 8%, with a larger variability in measurements of downwelling radiance (25%) compared to upwelling radiance (6%). Spectral shifts in the spectrometer relevant for SIF retrievals are consistently below 1 spectral pixel (up to 0.75). Found spectral shifts appear to be mostly dependent on temperature (as measured by a temperature probe in the instrument). Retrieved SIF shows a low variability of 1.8% compared with a noise reduced SIF estimate based on APAR. A combination of airborne imaging and in situ non-imaging fluorescence spectroscopy highlights the importance of a homogenous sampling surface and holds the potential to further uncover SIF retrieval issues as here shown for early evening acquisitions. Our experiments clearly indicate the need for careful site selection, measurement protocols, as well as the need for harmonized processing. This work thus contributes to guiding cal/val activities for the upcoming FLEX mission.

Published
2022

13. Combining near-infrared radiance of vegetation and fluorescence spectroscopy to detect effects of abiotic changes and stresses

Author

Zeng, Yelu, primary, Chen, Min, additional, Hao, Dalei, additional, Damm, Alexander, additional, Badgley, Grayson, additional, Rascher, Uwe, additional, Johnson, Jennifer E., additional, Dechant, Benjamin, additional, Siegmann, Bastian, additional, Ryu, Youngryel, additional, Qiu, Han, additional, Krieger, Vera, additional, Panigada, Cinzia, additional, Celesti, Marco, additional, Miglietta, Franco, additional, Yang, Xi, additional, and Berry, Joseph A., additional

Published
2022
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14. NIRVP: A robust structural proxy for sun-induced chlorophyll fluorescence and photosynthesis across scales

Author

Dechant, Benjamin, primary, Ryu, Youngryel, additional, Badgley, Grayson, additional, Köhler, Philipp, additional, Rascher, Uwe, additional, Migliavacca, Mirco, additional, Zhang, Yongguang, additional, Tagliabue, Giulia, additional, Guan, Kaiyu, additional, Rossini, Micol, additional, Goulas, Yves, additional, Zeng, Yelu, additional, Frankenberg, Christian, additional, and Berry, Joseph A., additional

Published
2022
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18. Estimating near-infrared reflectance of vegetation from hyperspectral data

Author

Zeng, Yelu, primary, Hao, Dalei, additional, Badgley, Grayson, additional, Damm, Alexander, additional, Rascher, Uwe, additional, Ryu, Youngryel, additional, Johnson, Jennifer, additional, Krieger, Vera, additional, Wu, Shengbiao, additional, Qiu, Han, additional, Liu, Yaling, additional, Berry, Joseph A., additional, and Chen, Min, additional

Published
2021
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19. 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

Author

Siegmann, Bastian, primary, Cendrero-Mateo, Maria Pilar, additional, Cogliati, Sergio, additional, Damm, Alexander, additional, Gamon, John, additional, Herrera, David, additional, Jedmowski, Christoph, additional, Junker-Frohn, Laura Verena, additional, Kraska, Thorsten, additional, Muller, Onno, additional, Rademske, Patrick, additional, van der Tol, Christiaan, additional, Quiros-Vargas, Juan, additional, Yang, Peiqi, additional, and Rascher, Uwe, additional

Published
2021
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20. Spatio-spectral deconvolution for high resolution spectral imaging with an application to the estimation of sun-induced fluorescence

Author

Scharr, H, Rademske, P, Alonso, L, Cogliati, S, Rascher, U, Scharr, Hanno, Rademske, Patrick, Alonso, Luis, Cogliati, Sergio, Rascher, Uwe, Scharr, H, Rademske, P, Alonso, L, Cogliati, S, Rascher, U, Scharr, Hanno, Rademske, Patrick, Alonso, Luis, Cogliati, Sergio, and Rascher, Uwe

Abstract

We propose a signal deconvolution procedure for imaging spectrometer data, where a measured point spread function (PSF) is deconvolved itself before being used for deconvolution of the signal. We evaluate the effectiveness of our procedure for improvement of the spatio-spectral signal, as well as our target application, i.e. estimation of sun-induced fluorescence (SIF). Imaging spectrometers are well established instruments for remote sensing. When used for scientific purposes these instruments are usually calibrated on a regular basis. In our case the point spread function of the optics is measured in an elaborate procedure with a tunable monochromator point light source. PSFs are measured at different pixel positions of the imaging sensor, i.e. at different spatio-spectral locations, and averaged in order to get an as accurate PSF as possible. We investigate error sources in this calibration process by simulating the procedure in silico. Averaging as well as the spectral and spatial width of the point source introduce some smoothness in the measured PSF. We propose corrective measures, i.e. deconvolution of the PSF itself and median instead of mean averaging, leading to a set of sharper PSFs. We test the performance of these PSFs in deconvolving simulated as well as real hyperspectral images. For deconvolution we test a set of well-known, off the shelf deconvolution algorithms. Quantitatively in terms of PSNR (Peak Signal to Noise Ratio) a combination of Wiener filtering and sharpened PSFs yields strongest improvements, while using Wiener filtering with non-sharpened PSFs even deteriorates the signal. Comparing deconvolution results of the simulated data with results of real data reveals, that visually very similar effects can be observed. This well supports the assumption, that our findings are also valid for real spatio-spectral data. Surprisingly, the choice of PSF, sharpened or not, is of little effect for SIF estimation with the iFLD algorithm in the O2A band

Published
2021

21. Response times of remote sensing measured sun-induced chlorophyll fluorescence, surface temperature and vegetation indices to evolving soil water limitation in a crop canopy

Author

Damm, Alexander, Cogliati, S, Colombo, R, Fritsche, L, Genangeli, A, Genesio, L, Hanus, J, Peressotti, A, Rademske, P, Rascher, Uwe, Schuettemeyer, D, Siegmann, B, Sturm, J, Miglietta, F, Damm, A, Cogliati, S, Colombo, R, Fritsche, L, Genangeli, A, Genesio, L, Hanus, J, Peressotti, A, Rademske, P, Rascher, U, Schuettemeyer, D, Siegmann, B, Sturm, J, Miglietta, F, University of Zurich, and Damm, Alexander

Subjects
Photochemical reflectance index, FIS/06 - FISICA PER IL SISTEMA TERRA E PER IL MEZZO CIRCUMTERRESTRE, MERIS terrestrial chlorophyll index, 1903 Computers in Earth Sciences, GEO/12 - OCEANOGRAFIA E FISICA DELL'ATMOSFERA, Soil Science, Geology, Multi-sensor remote sensing, 10122 Institute of Geography, Agricultural ecosystems, Agricultural ecosystem, ddc:550, Soil water limitation, Water band index, 910 Geography & travel, Computers in Earth Sciences, 1111 Soil Science, 1907 Geology
Abstract

Vegetation responds at varying temporal scales to changing soil water availability. These process dynamics complicate assessments of plant-water relations but also offer various access points to advance understanding of vegetation responses to environmental change. Remote sensing (RS) provides large capacity to quantify sensitive and robust information of vegetation responses and underlying abiotic change driver across observational scales. Retrieved RS based vegetation parameters are often sensitive to various environmental and plant specific factors in addition to the targeted plant response. Further, individual plant responses to water limitation act at different temporal and spatial scales, while RS sampling schemes are often not optimized to assess these dynamics. The combination of these aspects complicates the interpretation of RS parameter when assessing plant-water relations. We consequently aim to advance insight on the sensitivity of physiological, biochemical and structural RS parameter for plant adaptation in response to emerging soil water limitation. We made a field experiment in maize in Tuscany (Central Italy), while irrigation was stopped in some areas of the drip-irrigated field. Within a period of two weeks, we measured the hydraulic and physiological state of maize plants in situ and complemented these detailed measurements with extensive airborne observations (e.g. sun-induced chlorophyll fluorescence (SIF), vegetation indices sensitive for photosynthesis, pigment and water content, land surface temperature). We observe a double response of far-red SIF with a short-term increase after manifestation of soil water limitation and a decrease afterwards. We identify different response times of RS parameter representing different plant adaptation mechanisms ranging from short term responses (e.g. stomatal conductance, photosynthesis) to medium term changes (e.g. pigment decomposition, changing leaf water content). Our study demonstrates complementarity of common and new RS parameter to mechanistically assess the complex cascade of functional, biochemical and structural plant responses to evolving soil water limitation.

Published
2022
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25. Remote sensing of solar-induced chlorophyll fluorescence (SIF) in vegetation: 50 years of progress

Author

Mohammed, Gina H., primary, Colombo, Roberto, additional, Middleton, Elizabeth M., additional, Rascher, Uwe, additional, van der Tol, Christiaan, additional, Nedbal, Ladislav, additional, Goulas, Yves, additional, Pérez-Priego, Oscar, additional, Damm, Alexander, additional, Meroni, Michele, additional, Joiner, Joanna, additional, Cogliati, Sergio, additional, Verhoef, Wouter, additional, Malenovský, Zbyněk, additional, Gastellu-Etchegorry, Jean-Philippe, additional, Miller, John R., additional, Guanter, Luis, additional, Moreno, Jose, additional, Moya, Ismael, additional, Berry, Joseph A., additional, Frankenberg, Christian, additional, and Zarco-Tejada, Pablo J., additional

Published
2019
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26. Exploring the spatial relationship between airborne-derived red and far-red sun-induced fluorescence and process-based GPP estimates in a forest ecosystem

Author

Tagliabue, Giulia, primary, Panigada, Cinzia, additional, Dechant, Benjamin, additional, Baret, Frédéric, additional, Cogliati, Sergio, additional, Colombo, Roberto, additional, Migliavacca, Mirco, additional, Rademske, Patrick, additional, Schickling, Anke, additional, Schüttemeyer, Dirk, additional, Verrelst, Jochem, additional, Rascher, Uwe, additional, Ryu, Youngryel, additional, and Rossini, Micol, additional

Published
2019
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