Search results for "Earth Science"
showing 10 items of 2419 documents
Dynamique spatio-temporelle d’un événement extrême froid : impact de la circulation atmosphérique sur les basses températures en Bourgogne viticole.
2020
During April 2019 France experienced several frost events that caused extensive damage to almost all of its winegrowing regions. In Bourgogne-Franche-Comté the frost effects were very punctual and spatially diffused, the greatest damage being observed in the early bud breaking winegrowing sub-regions of Saône-et-Loire and the south of the Côte de Beaune. This study focuses on the multi-scalar analysis of the spring frost event underwent during the night between the 4th and 5th of April on a vineyard plot located in the Hautes Côtes de Beaune appellation. The analysis highlights the impact of local parameters (topography, surface discontinuity, etc.) on the spatio-temporal structuring of tem…
Sekcija "Arheologu un etnogrāfu pētījumi Latvijā 2018. – 2020. gadā" : Tēžu krājums
2021
Krājumā apkopotas 2021. gada 11. martā Latvijas Universitātes 79. starptautiskās zinātniskās konferences ietvaros Latvijas Universitātes Latvijas vēstures institūta organizētās sekcijas “Arheologu un etnogrāfu pētījumi Latvijā 2018. – 2020. gadā” nolasīto referātu tēzes. Tēzēs atspoguļojas LU Latvijas vēstures institūta, LU Vēstures un filozofijas fakultātes un Latvijas Nacionālā vēstures muzeja arheologu ieguldījums arheoloģiskā mantojuma un senvēstures aktuālu jautājumu izpētē. Tēzēs ietvertās atziņas balstītas padziļinātos, starpdisciplināros pētījumos, tās atspoguļo jaunu tēmu un arheoloģiskā materiāla interpretāciju meklējumus, kā arī arheoloģisko pieminekļu apzināšanas un izrakumu met…
Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012
2015
Abstract. Dehydration in the Antarctic winter stratosphere is a well-known phenomenon that is annually observed by satellites and occasionally observed by balloon-borne measurements. However, in situ measurements of dehydrated air masses in the Antarctic vortex are very rare. Here, we present detailed observations with the in situ and GLORIA remote sensing instrument payload aboard the German aircraft HALO. Strongly dehydrated air masses down to 1.6 ppmv of water vapor were observed as far north as 47° S in an altitude between 12 and 13 km in the lowermost stratosphere. The dehydration can be traced back to individual ice formation events above the Antarctic Peninsula and Plateau, where ice…
Raman Investigations to Identify Corallium rubrum in Iron Age Jewelry and Ornaments
2016
International audience; During the Central European Iron Age, more specifically between 600 and 100 BC, red precious corals (Corallium rubrum) became very popular in many regions, often associated with the so-called (early) Celts. Red corals are ideally suited to investigate several key questions of Iron Age research, like trade patterns or social and economic structures. While it is fairly easy to distinguish modern C. rubrum from bone, ivory or shells, archaeologists are confronted with ancient, hence altered, artifacts. Due to ageing processes, archaeological corals lose their intensive red color and shiny surface and can easily be confused with these other light colored materials. We pr…
Surcotes, tempêtes et risque d’inondation le long du littoral belge : variabilité contemporaine et future (1950-2100)
2010
6 pages; International audience; A l’échelle quotidienne, la hauteur des surcotes à Ostende est quasi-linéairement corrélée à la pressionatmosphérique de surface (PSM) sur la Mer Baltique. Les plus fortes surcotes s’y produisent quand une dépression restestationnaire plusieurs jours sur la Scandinavie synchrone à un renforcement de l’anticyclone des Açores. Cette géographiebarométrique favorise la genèse des forts vents d’afflux de nord-ouest dans la partie sud de la Mer du Nord. Un modèle derégression linéaire permet de simuler de façon robuste la variabilité interannuelle des fortes surcotes à Ostende de 1950 à2000 avec (i) la PSM autour de la Mer Baltique et (ii) le gradient barométrique…
Determinants of the interannual relationships between remote sensed photosynthetic activity and rainfall in tropical Africa
2007
International audience; The response of photosynthetic activity to interannual rainfall variations in Africa South of the Sahara is examined using 20 years (1981-2000) of Normalised Difference Vegetation Index (NDVI) AVHRR data. Linear correlations and regressions were computed between annual NDVI and annual rainfall at a 0.5° latitude/longitude resolution, based on two gridded precipitation datasets (Climate Prediction Center Merged Analysis of Precipitation [CMAP] and Climatic Research Unit [CRU]). The spatial patterns were then examined to detect how they relate to the mean annual rainfall amounts, land-cover types as from the Global Land Cover 2000 data set, soil properties and soil typ…
Acoustic wave guides as infinite-dimensional dynamical systems
2015
We prove the unique solvability, passivity/conservativity and some regularity results of two mathematical models for acoustic wave propagation in curved, variable diameter tubular structures of finite length. The first of the models is the generalised Webster's model that includes dissipation and curvature of the 1D waveguide. The second model is the scattering passive, boundary controlled wave equation on 3D waveguides. The two models are treated in an unified fashion so that the results on the wave equation reduce to the corresponding results of approximating Webster's model at the limit of vanishing waveguide intersection.
Contour map of the top of the regional geothermal reservoir of Sicily (Italy).
2015
An integrated review of existing geological and geophysical data – partly acquired during oil and gas exploration – combined with new data provided by deep geothermal studies of selected key areas, was used for the 3D modeling and mapping of the top of the geothermal reservoir developed at a regional scale in Sicily (Central Mediterranean). The resulting 1:500,000 scale map covers the area of the whole Sicily (about 25,700 km2) and is devoted to represent the main input for both the thermal modeling and the evaluation of geothermal potential at a regional scale. As the map indicates the distribution at depth of a likely target for geothermal drilling, it can be also used as a rough indicato…
Dynamics of hydrofracturing and permeability evolution in layered reservoirs
2015
International audience; A coupled hydro-mechanical model is presented to model fluid driven fracturing in layered porous rocks. In the model the solid elastic continuum is described by a discrete element approach coupled with a fluid continuum grid that is used to solve Darcy based pressure diffusion. The model assumes poro-elasto-plastic effects and yields real time dynamic aspects of the fracturing and effective stress evolution under the influence of excess fluid pressure gradients. We show that the formation and propagation of hydrofractures are sensitive to mechanical and tectonic conditions of the system. In cases where elevated fluid pressure is the sole driving agent in a stable tec…
Evolution des paysages Sahélines au cours des six dernières décennies dans la région de Niamey : de la disparition de la brousse tigrée à l'encroutem…
2010
In the Sahel, the rapid increase of the population during the last decades and the climate variation lead to an important environmental degradation. This work aims to measure the impacts of the human pressure on ecosystem during the six last decades. A diachronic cartography of a 100 km² area close to Niamey was done with aerial photographs (1950 and 1975) and GPS measurements (2009). Results showed that the tiger bush vegetation was completely cleared between 1950 and 2009 while the fallow decreases from 7 % to 1 %. In the sandy valley, the increase of cultivated fields from 20,7 % (1950) to 69,4 % (1975) favoured wind and water erosions which allowed surface soil crusting. Between 1975 an…