Search results for "Bas"
showing 10 items of 28787 documents
Measuring, modelling and managing gully erosion at large scales: A state of the art
2018
Soil erosion is generally recognized as the dominant process of land degradation. The formation and expansion of gullies is often a highly significant process of soil erosion. However, our ability to assess and simulate gully erosion and its impacts remains very limited. This is especially so at regional to continental scales. As a result, gullying is often overlooked in policies and land and catchment management strategies. Nevertheless, significant progress has been made over the past decades. Based on a review of >590 scientific articles and policy documents, we provide a state-of-the-art on our ability to monitor, model and manage gully erosion at regional to continental scales. In this…
Comparison of gap-filling techniques applied to the CCI soil moisture database in Southern Europe
2021
Abstract Soil moisture (SM) is a key variable that plays an important role in land-atmosphere interactions. Monitoring SM is crucial for many applications and can help to determine the impact of climate change. Therefore, it is essential to have continuous and long-term databases for this variable. Satellite missions have contributed to this; however, the continuity of the series is compromised due to the data gaps derived by different factors, including revisit time, presence of seasonal ice or Radio Frequency Interference (RFI) contamination. In this work, the applicability of different gap-filling techniques is evaluated on the ESA Climate Change Initiative (CCI) SM combined product, whi…
An autonomous petrological database for geodynamic simulations of magmatic systems
2022
SUMMARY Self-consistent modelling of magmatic systems is challenging as the melt continuously changes its chemical composition upon crystallization, which may affect the mechanical behaviour of the system. Melt extraction and subsequent crystallization create new rocks while depleting the source region. As the chemistry of the source rocks changes locally due to melt extraction, new calculations of the stable phase assemblages are required to track the rock evolution and the accompanied change in density. As a consequence, a large number of isochemical sections of stable phase assemblages are required to study the evolution of magmatic systems in detail. As the state-of-the-art melting diag…
Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake
2016
Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteri…
Impact of basin burial and exhumation on Jurassic carbonates diagenesis on both sides of a thick clay barrier (Paris Basin, NE France).
2014
27 pages; International audience; Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris Basin. The paragenetic sequences are compared in both aquifers to propose a diagenetic model for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy), structural (fracture orientations) and geochemical (δ18O, δ13C, REE) studies were conducted to characterize diagenetic cements, with a focus on blocky calcite cements, and their connection with fracturation events. Four generations of blocky calcite (Cal1-Cal4) are identified. Cal1 and Cal2 are widespread in the dominantly grain-supported facies of t…
THEMIS: A Parameter Estimation Framework for the Event Horizon Telescope
2020
This is an open access article.-- Full list of authors: Broderick, Avery E.; Gold, Roman; Karami, Mansour; Preciado-López, Jorge A.; Tiede, Paul; Pu, Hung-Yi; 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; Bronzwaer, Thomas; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chatterjee, Shami; Chatterjee, Koushik; Chen, Ming-Tang; Chen, Yongjun; Cho, Ilje; Conway, John E.; Cordes, James M.; Crew, Geoffrey B.; Cu…
Mapping Vegetation Density in a Heterogeneous River Floodplain Ecosystem Using Pointable CHRIS/PROBA Data
2012
River floodplains in the Netherlands serve as water storage areas, while they also have the function of nature rehabilitation areas. Floodplain vegetation is therefore subject to natural processes of vegetation succession. At the same time, vegetation encroachment obstructs the water flow into the floodplains and increases the flood risk for the hinterland. Spaceborne pointable imaging spectroscopy has the potential to quantify vegetation density on the basis of leaf area index (LAI) from a desired view zenith angle. In this respect, hyperspectral pointable CHRIS data were linked to the ray tracing canopy reflectance model FLIGHT to retrieve vegetation density estimates over a heterogeneous…
Astrometric detection of a low-mass companion orbiting the star AB Doradus
1997
International audience; We report submilliarcsecond-precise astrometric measurements for the late-type star AB Doradus via a combination of VLBI (very long baseline interferometry) and HIPPARCOS data. Our astrometric analysis results in the precise determination of the kinematics of this star, which reveals an orbital motion readily explained as caused by gravitational interaction with a low-mass companion. From the portion of the reÑex orbit covered by our data and using a revised mass of the primary star (0.76 M _) derived from our new value of the parallax (66.3 mas \ n \ 67.2 mas), we Ðnd the dynamical mass of the newly discovered companion to be between 0.08 and 0.11 If accurate photom…
The river harbour of Ostia Antica - stratigraphy, extent and harbour infrastructure from combined geophysical measurements and drillings
2018
Abstract We performed a combined geophysical and geoarchaeological survey of the harbour of ancient Ostia, Italy, to investigate the extent of the former harbour basin, the sedimentary infill and possible building remains around the harbour. Besides geoarchaeological results the paper highlights the advantage of combining vibracore drilling with different geophysical prospection methods, which are sensitive to different physical soil parameters. Geophysical methods applied were electrical resistivity tomography (ERT), ground penetrating radar (GPR) and seismics with shear and compressional waves. The extent and shape of the harbour basin were determined by ERT profiling. The ERT profiles we…
Oligo-Miocene lacustrine microbial and metazoan buildups from the Limagne Basin (French Massif Central)
2018
The Limagne Basin (French Massif Central) is an extensive continental lacustrine system accommodating microbial and metazoan buildups from Chattian to Aquitanian age. A description of these buildups and their associated biotic components in Grand Gandaillat and Crechy quarries provides insights into their spatio-temporal distribution patterns. Flats, cauliflowers, domes, cones and coalescent columnar morphologies have been identified with a main laminated mesofabric and laminated, columnar, filamentous and caddisfly-coated microfabrics. Two low-gradient margin models emerged based on the changes in the distribution, morphology and size of the microbial and metazoan-rich deposits through tim…