Search results for "Universe"

Précipitations en Afrique du Sud. Observations (1969-1998) et simulations (1969-2099).

2003

International audience

Instabilité spatio-temporelle des régimes pluviométriques dans le bassin-versant du Mono-Couffo (Afrique de l'Ouest) de 1961-2000.

2008

International audience

Variabilité climatique et pathologie dans le département du Mono (Bénin)

2006

International audience

Changement climatique et variabilité des ressources en eau dans le bassin de l'Alibori (Bénin, Afrique de l'Ouest)

2006

International audience

Timing and patterns of ENSO impacts in Africa over the last 30 years: insights from Normalized Difference Vegetation Index data.

2012

International audience; In this study we reassess and provide a more complete picture of the timing and patterns of ENSO impacts for the whole of Africa over the three last decades. We analyse the vegetation photosynthetic activity estimated by the NOAA-AVHRR Normalized Difference Vegetation Index (NDVI) rather than rainfall itself, because NDVI allows us to document the impacts at fine space and time scales. The use of the monthly time-step adds important new insights to the findings of previous works based largely on annual or seasonal time-scales and on a regional spatial-scale: several dipolar and propagative patterns are highlighted. In addition, we show that the less-studied winter ra…

Spatial coherence of agronomic boreal monsoon onset over Western and Central Sahel (1950-2000).

2007

Poster Presentation

Etude isotopique et spatialisation du carbone dans l'agglomération dijonnaise

2005

Intraseasonal oscillations of the East African long rains and their connection with MJO activity over the Indian Ocean

2005

Our understanding of the East African long rains (March-May) variability remains relatively poor. Interannual variations are quite small compared to intraseasonal vari- ations. An analysis of pentad rainfall and OLR data shows organised variations in the range of 20-75 days, though quite irregular from year to year. However, rainfall and OLR variations are strongly consistent over the highland region only. For this region, NCEP-DOE II reanalysis data are used to detect atmospheric patterns associated to wet events. Significant zonal wind anomalies, of opposite sign at 850 and 200 hPa, are found locally over East Africa. Anomalous low-level westerlies (upper-level easter- lies) are observed d…

Concentrations de NO2 développement d'un SIG et influence de la météorologie à Dijon durant l'hiver 1999

2000

ACTI; International audience; A nitrogen dioxide (NO2) measurements campaign, with passive diffusion tubes, realised by ATMOSF'Air during the winter 1999, allows to realise an atmospheric pollution study in the Dijon urban area. In order to understand the spatial NO2 distribution in the urban area, NO2 is correlated with NO emissions and topography thanks to a Geographical Information System (GIS). With a multiple linear regression, NO2 concentrations are explained principally by traffic and topography. A Principal Components Analysis shows the necessity to nuance the relation between these variables. So, the meteorological datas of Dijon-Longvic, could explain the different NO2 distributio…

The Madden-Julian Oscillation (MJO) impacts on Southern African summer rainfall and Tropical-Temperate Interactions

2006

Composite maps of outgoing longwave radiation (OLR) anomalies over the Madden–Julian oscillation (MJO) cycle show marked intraseasonal fluctuations over southern Africa (south of 15°S). Large-scale convective clusters are seen to propagate eastward and then northward over the continent, mainly between 10° and 20°S. The corresponding response of the rainfall field presents the alternation, over the cycle, of dry and humid phases, which are both significant. Moisture flux anomalies indicate an intraseasonal modulation of the midtropospheric easterly flow over the Congo basin at 700 hPa; these fluctuations are coupled to meridional flux anomalies that extend from the tropical to the subtropica…