Search results for "Précipitation"
showing 9 items of 39 documents
Étude climatique de la mousson vietnamienne et applications à la prévision saisonnière
2008
This thesis aims at documenting the physical and dynamic processes associated with the monsoon circulation of Vietnamese regional and synoptic scales, to explore the predictability of its key components and develop statistical and dynamical methods for forecasting the monsoon onset and seasonal. It is divided into two parts. The first part is, in fact, a climate study based on analysis of diagnostic data: - first, the monthly rainfall and temperature data station over the period 1960-2000 are used to analyze the cycle and the variability of these fields on the seven traditional climatic regions of Vietnam using the observed precipitation in various stations. Classifications and correlations…
Temporal evolution of heavy rainfall in the southern West Africa coastline belt.
2018
The Southern Coastalbelt of West Africa (SCWA) is exposed to recurrent flooding. The two objectives of the study are to show thespecificity of SCWA to heavy rainfall occurrence and to determine the trends of the latter. Daily rainfall data of41 stations in the southern parts of Côte d’Ivoire, Ghana, Togo and Benin for the period 1951–2015 and ClimateHazards Group InfraRed Precipitation data were used. The approach is based on the determination (for eachstation and grid point) of the 95th centile (P95) of precipitations greater than or equal to 1 mm. Results indicatethat rainfall is heavier on the coastal belt than inland (average P95 is 65,4 and 45,5 m/day for coastal and inlandstations res…
Cropping system dynamics, climate variability, and seed losses among East African smallholder farmers: a retrospective survey.
2014
Abstract Climate variability directly affects traditional low input and rain-fed farming systems, but few studies have paid attention retrospectively to the cropping system’s ability to mitigate climate risk. This study analyzes the impacts of rainfall variability on farmers’ seed variety losses over time, considering changes in smallholder farming systems. The cropping system dynamics, in favoring maize at the expense of sorghum and pearl millet, have induced an increasing risk of seed loss during drought. Combining ecological anthropology and climatology, a retrospective survey asking farmers about the period 1961–2006 was carried out at three altitudinal levels (750, 950, and 1100 m) on …
Réponse des interactions plante-sol aux régimes de précipitations
2018
Water availability governs terrestrial nutrient cycles by impacting the functioning of both plants and of soil microorganisms. The predicted changes in precipitation patterns (i.e. the magnitude and frequency of precipitation events) associated with climate change, will thus likely have important consequences on ecosystem functioning. Dry and seasonally dry ecosystems are particularly vulnerable to changes in precipitation patterns, as they are already constrained to a large extent by water availability. However, more mesic systems may also experience dry periods that may impact plant-soil functions. In this thesis, experiments in soil-only systems and plant-soil systems were used to gain i…
Elaboration de céramiques transparentes Er YAG : synthèse de poudre par co-précipitation et frittage SPS
2013
Yttrium aluminium garnet (YAG, Y3Al5O12) transparent ceramics have attracted much attention since it can replace single crystals as host materials in solid state heat capacity lasers. These polycrystalline ceramics present improved mechanical and spectroscopic properties, as well as a better heat conductivity, lower fabrication costs for larger size materials. Furthermore, it is possible to reach higher doping concentrations as well a uniform distribution. Doping YAG with Erbium (Er:YAG) allows eye-safe emission at 1645nm. Moreover, a low doping rate (0.5%at.) enables upconversion process during laser operation. Conditions for transparency are amongst others, the absence of defects, a high …
État actuel des réseaux de mesures éco-climatiques en Afrique centrale : les ambitions du projet de recherche international FORGREENE.
2016
This work presents an overview of spatio-temporal quality andspatial density of rainfall networks of Cameroon, Gabon, Congo, CAP and DRC, particularly in the recentperiod (1973-2014) through the GSOD international database. Faced with enormous gaps observed, theseresults will help to select metrological and analytical orientations in FORGREENE project (Tropical forestsgreeness and cloudiness in Central Africa: present conditions and future evolution). A comparison with rainfallsatellite estimates (RFE type) also indicates their great potential, provided they are based on in situ validations.
Radar-rain gauges intercomparison for the estimation of high resolution rainfall.
2015
An accurate rainfall estimation is essential for many applications like precision viticulture. Rainfall is most of the time estimated by two methods:radar and rain gauges. High resolution rain gauges network Hydravitis was installed in 2014. Data coming from radar,composite product and the network was extracted for the 2014 3 to 4 November event. Data from the network were kriged tocompare with the other products. Results show that PANTHERE radar image well reproduces the spatial variability ofrainfall but underestimates rainfall amounts over a 4 mm/h intensité. Composite product ANTILOPE gives a goodvisualization of spatial variability and intensity of rainfall. Expectations of viticulture…
Évolution des précipitations extrêmes dans le bassin versant du Mono (Bénin-Togo) en contexte de variabilité / changement climatique.
2014
International audience; Dans le golfe de Guinée et dans le bassin du Mono, au Bénin-Togo, en particulier, la population est de plus enplus exposée aux événements de précipitations extrêmes ou à l’intensité de ces événements causant des inondations de plusen plus récurrentes dans un environnement où on assiste à une croissance démographique galopante. L’objectif de cetteétude est : 1) d’analyser l’évolution des précipitations extrêmes dans le bassin au cours de la période 1988-2010 à partir dedonnées pluviométriques krigées ; 2) d’effectuer une comparaison avec les simulations régionales à 50 km de résolutionproduites par les modèles MPI, ICT, SMH et METO dans le cadre du projet Européen ENS…
Estimation du rayonnement solaire dans le sud-ouest de l’océan Indien et a la Réunion : modélisation régionale du climat.
2014
6 pages; International audience; On analyse ici la capacité du modèle climatique régional RegCM4 à simuler les champs radiatifs, la températurede surface et les précipitations sur un domaine couvrant l’Afrique australe et le sud-ouest de l’océan Indien (0-40°S ; 0-100°E), centré sur La Réunion. Les données produites par le modèle sont confrontées aux données d’observations CERESpour les paramètres du rayonnement (ondes courtes et longues) et GPCP pour les précipitations, et aux données desréanalyses ERA-Interim pour la température. Six simulations ont été conduites, chacune avec un schéma de convectiondifférent, afin de tester la sensibilité des résultats à la physique du modèle.Le schéma m…