Sudan-Sahel rainfall onset: Definition of an objective index, types of years, and experimental hindcasts

Using rainfall estimates from the 5-day version of CPC Merged Analysis of Precipitation (CMAP) and Global Precipitation Climatology Project data along with multiscale spatial key descriptors of atmospheric dynamics from National Center for Environmental Prediction/Department of Energy reanalysis 2 (NCEP/DOE), we first define a West African monsoon onset index to determine its successive dates of occurrence over the period 1979-2004 (28-29 June in mean with a standard deviation of 8.5 days). Then we focus on the three main types of time evolutions of that index at the moment of the monsoon onset in terms of precipitation, pressure, temperature, and winds at different levels to detect the mos…

"Abundance of main vectors of malaria and climatic factors: the case of Ndiop and Dielmo villages (Sine Saloum, Senegal)"

International audience

Definition and predictability of an OLR based West African monsoon onset

The monsoon onset is documented in terms of latitudinal shift of deep convection areas within the ITCZ using an interpolated version of the National Oceanic and Atmospheric Administration (NOAA) Outgoing Longwave Radiation (OLR) at a 5-day time-step over West Africa for the period 1979–2004. Signals in moist convection derived from OLR values lower than 180 W/m2 allow better determination of onset dates (ODs) than the use of other thresholds or of the raw values of OLR. Such ODs are defined without any time filtering or spatial averaging along the meridional plane. They are also significantly correlated with ODs based on other datasets such as the CMAP and Global Precipitation Climatology P…

Impact des facteurs climatiques sur la présence et l'abondance saisonnière des principaux vecteurs du paludisme en Afrique soudano-sahélienne

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How using large scale rainfall datasets over West Africa ?

Etude d'impact de la variabilité saisonnière des paramètres environnementaux sur les vecteurs du paludisme dans les villages de Ndiop et Dielmo (Sénégal)

Action Thématique Interdépartementale de l'IRD "Evolution Climatique et Santé"; Séminaire AMMA, Montpellier

Changements d'échelle et sorties climatiques régionalisées

Les modèles numériques de circulation générale produisent des champs climatiques sur un maillage trop grossier. Certains paramètres varient beaucoup localement en fonction de leur environnement (relief, végétation...). C'est le cas des précipitations, lorsqu'elles sont essentiellement convectives comme en Afrique. Les méthodes et outils permettant un dialogue entre ces deux échelles vont des modèles emboîtés aux modèles statistiques, en passant par des approches mixtes. Ces techniques en développement deviennent nécessaires si l'on veut mener correctement les études d'impact liées à la variabilité climatique à court ou moyen terme, particulièrement pour ce qui concerne l'extension des malad…

Climate Adjustments over Africa Accompanying the Indian Monsoon Onset

Abstract Rainfall and circulation changes accompanying the Indian monsoon onset are examined, focusing on the African continent and neighboring areas. The Indian Meteorological Department official monsoon onset dates over Kerala (MOK; on average on 1 June) are used. Composites are formed at a pentad (5 days) time scale to compare pre- and postonset conditions. Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) data for 1979–2007 indicate that a substantial rainfall decrease over several parts of Africa is associated with MOK. Significant rainfall anomalies, after removal of the mean seasonal cycle, are found in eastern Africa and the nearby western Indian Ocean. Indian …

Detecting the West African monsoon onset

International audience

Detection of intra-seasonnal leading signals for the rainfall onset over the Sudanian and Sahelian belts : experimental hindcast

International audience

An OLR based West African monsoon onset index

International audience