Search results for "Climatologie"
showing 10 items of 39 documents
A genomic map of climate adaptation in Mediterranean cattle breeds
2019
International audience; Domestic species such as cattle (Bos taurus taurus and B. t. indicus) represent attractive biological models to characterize the genetic basis of short term evolutionary response to climate pressure induced by their post-domestication history. Here, using newly generated dense SNP genotyping data, we assessed the structuring of genetic diversity of 21 autochtonous cattle breeds from the whole Mediterranean basin and performed genome-wide association analyses with covariables discriminating the different Mediterranean climate sub-types. This provided insights into both the demographic and adaptive histories of Mediterranean cattle. In particular, a detailed functional…
Social process of adaptation to environmental changes: How eastern african societies intervene between crops and climate
2014
Abstract Studies on climate change can only be conducted on a long time scale, and observing how societies adapt their sowing practices to climate variability is challenging and costly. As an alternative, a space and time substitution design was used, changes in space corresponding to that induced in time by environmental change. On the eastern slope of Mount Kenya, the Tharaka community, originating from the lowlands (750 m), moved up to the midlands (950 m) with their lowland-adapted resources, whereas the Mwimbi, originating from wetter upland (1100 m), moved down to the midlands with their highland-adapted genetic resources. A weather station was installed at 950 and 1100 m, and a logis…
Peaks of in situ N2O emissions are influenced by N2O producing and reducing microbial communities across arable soils
2018
International audience; Introduction Agriculture is the main source of terrestrial N2O emissions, a potent greenhouse gas and the main cause of ozone depletion ((Hu et al., 2015). The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only known biological process eliminating this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers (nosZII) was related to the potential capacity of the soil to act as a N2O sink (see Hallin et al., 2017 and references therein). However little is known about how this group responds to different agricultural practices. Here, we investigated how N2O-producers and N2O-reducers were …
Etudes climatiques régionales Applications à la variabilité pluviométrique en Afrique australe et orientale et à la qualité de l'air en Bourgogne
2004
Les chapitres 1 à 4 concernent l'Afrique, et essentiellement l'Afrique australe Chapitre 1 : Aspects spatiaux et saisonniers de la variabilité pluviométrique Excédents et déficits pluviométriques sont en priorité liés à des modifications de l'amplitude du régime pluviométrique saisonnier. La variabilité interannuelle s'inscrit dans un cadre spatial contraint par les régimes pluviométriques moyens. Néanmoins, certaines saisons sont plus propices au développement d'anomalies généralisées. Tel est le cas des short rains en Afrique de l'Est. Les anomalies pluviométriques majeures interviennent lors de la saison des pluies mais ne revêtent pas un caractère homogène. En Afrique du Sud, Octobre se…
Bias correction of dynamically downscaled precipitation to compute soil water deficit for explaining year-to-year variation of tree growth over north…
2017
This paper documents the accuracy of a post-correction method applied to precipitation regionalized by the Weather Research and Forecasting (WRF) Regional Climate Model (RCM) for improving simulated rainfall and feeding impact studies. The WRF simulation covers Burgundy (northeastern France) at a 8-km resolution and over a 20-year long period (1989–2008). Previous results show a strong deficiency of the WRF model for simulating precipitation, especially when convective processes are involved. In order to reduce such biases, a Quantile Mapping (QM) method is applied to WRF-simulated precipitation using the mesoscale atmospheric analyses system SAFRAN («Système d'Analyse Fournissant des Rense…
The onset of the rainy season and farmers’ sowing strategy for pearl millet cultivation in Southwest Niger
2011
A multi-year (2004-2009) field survey of on-farm sowing practices in 10 villages located in south-west Niger close to Niamey, is analysed to investigate the relationships (i) between rainfall and the sowing date of pearl millet and the risk of sowing failure, (ii) between sowing and meteorological/agro-climatic onset dates, (iii) between sowing/onset dates, and simulated and observed yield/biomass at the end of the season. Even if some villages sow without any synchronous or anterior rainfall, most parcels (73% out of the 1551 available cases) are sown during and just after a 2-day wet spell receiving at least 10 mm. In fact, there is a strong correlation (r = 0.82-0.95 depending on onset d…
Radiative surface temperature and convective flux calculation over crop canopies
1988
The analysis presented in this paper aims at a better understanding of the potential role of radiative temperature, as measured by a radiometer over crops, in sensible heat flux calculation. Defining radiative temperature as the mean temperature of the surfaces viewed by the radiometer (leaves and soil surface) and assuming that an Ohm's law type formula can be used to express sensible heat flux as a function of the difference between air temperature and radiative temperature, the aerodynamic resistance which divides this temperature difference has been analytically defined. The parameters which appear in the resistance expression depend essentially on wind velocity and canopy structure but…
Interactions surface continentale/atmosphère : l'expérience HAPEX-Sahel
1994
L'évolution saisonnière des termes du bilan radiatif, du bilan d'énergie et la production primaire d'une savane humide d'Afrique de l'Ouest (Lamto, Côte d'Ivoire) a été suivie dans le cadre du programme SAvanes à Long Terme (SALT). Ces données ont permis de développer un modèle de simulation des échanges surface/atmosphère en savane humide, basé sur les relations fonctionnelles existant entre la production et la phénologie de la savane d'une part, et les bilans d'énergie et hydrique de ce type de surface d'autre part. Ce modèle est issu du couplage de deux sous-modèles fonctionnant au pas de temps journalier et utilisant des variables climatiques standard en entrée : le modèle de bilan d'én…
Changements climatiques et océanographiques au cours du Campanien – approche couplée minéralogie et géochimie
2018
The origin of the Late Cretaceous (~100 – 65 Ma) global cooling is not yet well understood. The evolution of sea surface and bottom temperatures shows an acceleration of the cooling during the Campanian stage (~84 Ma). The main goal of this study was to explore the processes driving this cooling, focusing on Campanian sediments from the Tethyan, Boreal and Atlantic realms.The clay mineralogical assemblages of several (hemi)pelagic sites, selected along a S-N transect, from 5° to 45°N, reveal an increase in continental weathering during the Campanian, expressed by enhanced kaolinite inputs. The detrital input related to the uplift of new continental areas seems to evolve from south to north.…
L'activité dépressionnaire et anticyclonique hivernale des moyennes latitudes du Pacifique Nord
2007
Using a new automated scheme, synoptic mid-latitudes cyclone and anticyclone trajectories have been constructed over the North Pacific from daily sea level pressure (SLP) data, covering the period 1950-2001. Over the North-Eastern Pacific, the strength of anticyclones diminished and their frequency became more variable, while cyclones intensified and presented further southerly trajectories since the mid-1970s. Thus, cyclonic and anticyclonic activities are significantly anti-correlated. These transient activity changes averaged out into anomalously low winter mean SLP in the Aleutian Low region, consistent with the positive phase of the North Pacific Oscillation, inducing positive sea surf…