Search results for "Planetary Science"
showing 10 items of 4367 documents
Multitemporal unmixing of MERIS FR data
2007
Compensation of Oxygen Transmittance Effects for Proximal Sensing Retrieval of Canopy–Leaving Sun–Induced Chlorophyll Fluorescence
2018
Estimates of Sun–Induced vegetation chlorophyll Fluorescence (SIF) using remote sensing techniques are commonly determined by exploiting solar and/or telluric absorption features. When SIF is retrieved in the strong oxygen (O 2 ) absorption features, atmospheric effects must always be compensated. Whereas correction of atmospheric effects is a standard airborne or satellite data processing step, there is no consensus regarding whether it is required for SIF proximal–sensing measurements nor what is the best strategy to be followed. Thus, by using simulated data, this work provides a comprehensive analysis about how atmospheric effects impact SIF estimations on proximal sensing, regarding: (…
Verification of Radiative Transfer Schemes for the EHT
2020
Authors: Gold, Roman; Broderick, Avery E.; Younsi, Ziri; Fromm, Christian M.; Gammie, Charles F.; Mościbrodzka, Monika; Pu, Hung-Yi; Bronzwaer, Thomas; Davelaar, Jordy; Dexter, Jason; Ball, David; Chan, Chi-kwan; Kawashima, Tomohisa; Mizuno, Yosuke; Ripperda, Bart; Akiyama, Kazunori; Alberdi, Antxon; Alef, Walter; Asada, Keiichi; Azulay, Rebecca Baczko, Anne-Kathrin; Baloković, Mislav; Barrett, John; Bintley, Dan; Blackburn, Lindy; Boland, Wilfred; Bouman, Katherine L.; Bower, Geoffrey C.; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broguiere, Dominique; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chatterjee, Koushik; Chatterjee, Shami; Chen, Ming-T…
First M87 Event Horizon Telescope Results. VII. Polarization of the Ring
2021
Full list of authors: Akiyama, Kazunori; Algaba, Juan Carlos; Alberdi, Antxon; Alef, Walter; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Baczko, Anne-Kathrin; Ball, David; Baloković, Mislav; Barrett, John; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Boland, Wilfred; Bouman, Katherine L.; Bower, Geoffrey C.; Boyce, Hope Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chan, Chi-kwan; Chatterjee, Shami; Chatterjee, Koushik; Chen, Ming-Tang; Chen, Yongjun; Chesler, Paul M.; Cho, Ilje; Christian, Pierre; Conway, John E.…
2021
Nitrogen (N) is one of the key nutrients supplied in agricultural production worldwide. Over-fertilization can have negative influences on the field and the regional level (e.g., agro-ecosystems). Remote sensing of the plant N of field crops presents a valuable tool for the monitoring of N flows in agro-ecosystems. Available data for validation of satellite-based remote sensing of N is scarce. Therefore, in this study, field spectrometer measurements were used to simulate data of the Sentinel-2 (S2) satellites developed for vegetation monitoring by the ESA. The prediction performance of normalized ratio indices (NRIs), random forest regression (RFR) and Gaussian processes regression (GPR) f…
Spatio-temporal soil drying in southeastern South America: the importance of effective sampling frequency and observational errors on drydown time sc…
2020
The study of the spatio-temporal dynamics of surface soil moisture (SSM) drydowns integrates the soil response to climatic conditions, drainage and land cover and is key to advances in our knowledg...
Transition vers des systèmes agricole et agroalimentaire durables : quelle place et qualification pour les légumineuses à graines ?
2017
Cet article propose une analyse historique du processus de verrouillage du système agroalimentaire en défaveur des légumineuses à graines, à l’aune des théories évolutionnistes. Plusieurs mécanismes d’autorenforcement permettent de comprendre pourquoi ces espèces sont de moins en moins cultivées en France face à un système agro-industriel qui s’est spécialisé en faveur des céréales, favorisant à l’amont l’usage d’engrais azotés de synthèse et limitant à l’aval les investissements pour les légumineuses en alimentation humaine. Cet article s’interroge alors sur les perspectives de déverrouillage.
Satellite Observations of the Contrasting Response of Trees and Grasses to Variations in Water Availability
2019
Interannual variations in ecosystem primary productivity are dominated by water availability. Until recently, characterizing the photosynthetic response of different ecosystems to soil moisture anomalies was hampered by observational limitations. Here, we use a number of satellite-based proxies for productivity, including spectral indices, sun-induced chlorophyll fluorescence, and data-driven estimates of gross primary production, to reevaluate the relationship between terrestrial photosynthesis and water. In contrast to nonwoody vegetation, we find a resilience of forested ecosystems to reduced soil moisture. Sun-induced chlorophyll fluorescence and data-driven gross primary production ind…
Information nutritionnelle, choix et caractéristiques des consommateurs
2012
Consumers’ food decisions are based on the information they receive and on their own individual characteristics. This paper is based on an experiment using experimental economics and sensory evaluation to measure individual characteristics of participants and to analyze the impact of nutritional information relative to orange juice. The aim is to explore the potential link between specific characteristics (risk aversion, time preference) and the reactions of consumers to nutritional information. The results show that participants react significantly to this information supplied, positively for the pure orange juice and a negatively for orange nectars. In addition, “risk averse” individuals …
Monitoring Cropland Phenology on Google Earth Engine Using Gaussian Process Regression
2021
Monitoring cropland phenology from optical satellite data remains a challenging task due to the influence of clouds and atmospheric artifacts. Therefore, measures need to be taken to overcome these challenges and gain better knowledge of crop dynamics. The arrival of cloud computing platforms such as Google Earth Engine (GEE) has enabled us to propose a Sentinel-2 (S2) phenology end-to-end processing chain. To achieve this, the following pipeline was implemented: (1) the building of hybrid Gaussian Process Regression (GPR) retrieval models of crop traits optimized with active learning, (2) implementation of these models on GEE (3) generation of spatiotemporally continuous maps and time seri…