Search results for "ENSO"
showing 10 items of 5582 documents
Potential of Automated Digital Hemispherical Photography and Wireless Quantum Sensors for Routine Canopy Monitoring and Satellite Product Validation
2021
To better characterize the temporal dynamics of vegetation biophysical variables, a variety of automated in situ measurement techniques have been developed in recent years. In this study, we investigated automated digital hemispherical photography (DHP) and wireless quantum sensors, which were installed at two sites under the Copernicus Ground Based Observations for Validation (GBOV) project. Daily estimates of plant area index (PAI) and the fraction of absorbed photosynthetically active radiation (FAPAR) were obtained, which realistically described expected vegetation dynamics. Good correspondence with manual DHP and LAI-2000 data (RMSE = 0.39 to 0.90 for PAI, RMSE = 0.07 for FAPAR) provid…
A multisensor fusion approach to improve LAI time series
2011
International audience; High-quality and gap-free satellite time series are required for reliable terrestrial monitoring. Moderate resolution sensors provide continuous observations at global scale for monitoring spatial and temporal variations of land surface characteristics. However, the full potential of remote sensing systems is often hampered by poor quality or missing data caused by clouds, aerosols, snow cover, algorithms and instrumentation problems. A multisensor fusion approach is here proposed to improve the spatio-temporal continuity, consistency and accuracy of current satellite products. It is based on the use of neural networks, gap filling and temporal smoothing techniques. …
The high overtone and combination levels of SF6 revisited at Doppler-limited resolution: A global effective rovibrational model for highly excited vi…
2017
Abstract Sulfur hexafluoride is an important prototypal molecule for modeling highly excited vibrational energy flow and multi quanta absorption processes in hexafluoride molecules of technological importance. It is also a strong greenhouse gas of anthropogenic origin. This heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 =1 vibrational state. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 120 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectr…
PHYSICS-based retrieval of scattering albedo and vegetation optical depth using multi-sensor data integration
2017
Vegetation optical depth and scattering albedo are crucial parameters within the widely used τ-ω model for passive microwave remote sensing of vegetation and soil. A multi-sensor data integration approach using ICESat lidar vegetation heights and SMAP radar as well as radiometer data enables a direct retrieval of the two parameters on a physics-derived basis. The crucial step within the retrieval methodology is the calculus of the vegetation scattering coefficient KS, where one exact and three approximated solutions are provided. It is shown that, when using the assumption of a randomly oriented volume, the backscatter measurements of the radar provide a sufficient first order estimate and …
Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers
2019
Growing interest in the proximal sensing of sun-induced chlorophyll fluorescence (SIF) has been boosted by space-based retrievals and up-coming missions such as the FLuorescence EXplorer (FLEX). The European COST Action ES1309 “Innovative optical tools for proximal sensing of ecophysiological processes” (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) has produced three manuscripts addressing the main current challenges in this field. This article provides a framework to model the impact of different instrument noise and bias on the retrieval of SIF; and to assess uncertainty requirements for the calibration and characterization of state-of-the-art SIF-oriented spectroradiom…
Estimating Gravimetric Moisture of Vegetation Using an Attenuation-Based Multi-Sensor Approach
2018
Estimating parameters for global climate models via combined active and passive microwave remote sensing data has been a subject of intensive research in recent years. A variety of retrieval algorithms has been proposed for the estimation of soil moisture, vegetation optical depth and other parameters. A novel attenuation-based retrieval approach is proposed here to globally estimate the gravimetric moisture of vegetation (m g ) and retrieve information about the amount of water [kg] per amount of wet vegetation [kg]. The parameter m g is particularly interesting for agro-ecosystems, to assess the status of growing vegetation. The key feature of the proposed approach is that it relies on mu…
High-resolution spectroscopy and analysis of the V2 + V3 combination band of SF6 in a supersonic jet expansion
2013
International audience; Sulphur hexafluoride is a very strong greenhouse gas whose concentration is increasing in the atmosphere. It is detected through infrared absorption spectroscopy in the strong ν3 fundamental region. Due to the existence of low-lying vibrational states of this molecule, however, many hot bands arise at room temperature and those are still not known. We present here a contribution to the elucidation of this hot band structure, by analysing the ν2 + ν3 combination band. We use a supersonic jet expansion high-resolution spectrum at a rotational temperature of ca. 25 K that was recorded thanks to the Jet-AILES setup at the Source Optimisée de Lumière d'Energie Intermédiai…
Antropologia come "general Weltkenntniß" Kant e la concezione cosmica dell'umano
2018
Il progetto antropologico di un mondo-ambiente nel quale l'uomo, grazie allo sviluppo delle proprie capacità, trova la sua posizione e conquista un ruolo centrale, si inserisce, in Kant, all'interno in un disegno più ampio che pone l'uomo al cospetto di scopi la cui realizzazione va ben al di là di quel che egli può fare; va ben al di là dell'immagine pragmatica di un mondo pensato e progettato a misura d'uomo. Come risulta insufficiente, dunque, ogni antropologia fisiologica che rimanga limitata al punto di vista dell'uomo in quanto prodotto del gioco della natura, altrettanto insufficiente risulterebbe un'antropologia pragmatica che si legasse unicamente alla rappresentazione antropocentr…
Coastal Oceanic climate change and variability from 1982 to 2009 around South Africa
2010
Changes and fluctuations in sea surface temperature (SST) around the South African coast are analysed at a monthly scale from 1982 to 2009. There is a statistically significant negative trend of up to 0.5 °C per decade in the southern Benguela from January to August, and a cooling trend of lesser magnitude along the South Coast and in the Port Elizabeth/Port Alfred region from May to August. The cooling is due to an increase in upwelling-favourable south-easterly and easterly winds. There is a positive trend in SST of up to 0.55 °C per decade in most parts of the Agulhas Current system during all months of the year, except for KwaZulu-Natal where warming is in summer. The warming was attri…
Effect of addition of Opuntia ficus-indica mucilage on the biological leavening, physical, nutritional, antioxidant and sensory aspects of bread
2019
The addition of active compounds to enhance the functional properties of foods is a quite common practice. Recently, bread became one of the target foods to incorporate functional ingredients such as those deriving from Opuntia spp. So far, only Opuntia ficus-indica cladodes in powder has been tested. The addition of fresh O. ficus-indica mucilage (in substitution to water) did not influence the biological leavening of the doughs. The resulting breads showed a biological role of the cactus mucilage, because their antioxidant activity was higher than that of control wheat bread. The sensory analysis indicated a general appreciation of the breads enriched with O. ficus-indica mucilage by the …