Search results for "changes"

Vegetation - atmosphere feedback in West Africa on time scales of weeks to months

2010

Rainfall exerts a strong control on the seasonal evolution of vegetation across West Africa. In turn vegetation, and the root zone soil moisture which influences its growth, controls the fluxes of water and heat back into the atmosphere. This provides a mechanism for the land to feed back on the large-scale circulation over the course of the annual cycle. In this study, satellite data are combined with the outputs from land surface models and atmospheric reanalysis to develop an overview of where and when such feedbacks can occur in the region. The influence of rainfall on vegetation cover is re-examined using satellite data from the period 2000-8. MODIS Normalised Vegetation Difference Ind…

Relationships between dust aerosols and meningitis epidemics using satellite data sets

2010

Pollution en ozone en Bourgogne Orientale

2000

International audience; Ozone concentrations in Burgundy, and particularly for the two principal agglomerations, Dijon and Chalon-sur-Saône, are studied on the 1998 and 1999 summers (April-September). A Principal Component Analysis is carried out to examine their relationships with meteorological conditions and nitrogen oxides (NOx). The episodes are associated with summer warm, dry and sunny weather conditions, which are established during several days when Northerly or Easterly winds prevail. The entire region is affected. Night patterns of ozone are more heterogeneous with a higher chemical destruction in Chalon. Outside episodes, night concentrations are for a large part controlled by t…

Agrégation des données de températures en Bourgogne : Sensibilité aux échelles de temps.

2010

SOUMIS; L'étude de la variabilité spatiale du climat ou de potentialités agricoles nécessite des champs continus de variables climatiques. Les températures sont mesurées de façon ponctuelle par des stations météorologiques. Il est donc nécessaire d'agréger ces données dans l'espace c'est-à-dire d'estimer la valeur de la variable ‘température' en tous points de la région d'étude (la Bourgogne, France). Dans ce but, une méthode déterministe est utilisée : les splines partielles en plaque mince Elle est appliquée pour les années 1991 et 2003, aux pas de temps annuel, mensuel et quotidien. L'altitude est intégrée dans la procédure d'interpolation, comme covariable environnementale. La performan…

About the potential role of desert dust in the West African meningitis epidemics

2007

Cohérence spatiale et prévisibilité potentielle du démarrage de la saison des pluies en Afrique soudano-sahélienne

2010

In-Water Reflectance Spectra Measured On Board a Jet-Ski Across a Complex Nearshore Zone of Case-2 Waters during the ECORS Experiment

2008

International audience

Zonal circulations over the Indian and Pacific oceans and the level of lakes Victoria and Tanganyika.

2004

International audience

Climate-related activities within the Southern African Development Community (SADC) region.

2012

4 pages; International audience

Advances in the analyses of dust/climate and meningitis relationships based on a multidisciplinary approach

2009

International audience