Rainfall and environmental controls of the vegetation patterns at the beginning of the rainy season in semi-arid South Africa.

Soumis; International audience

Analysis of the relationship between start of the rainy season and farmer's sowing strategy in the Niamey area and its impacts on the pearl millet yield

International audience; Relationship between start of the rainy season and farmer's planting date have been analysed at local scale through in situ daily rainfall records and agronomical measurement provided by on-farm survey at plot scale for 10 villages network located on the mesoscale AMMA-CATCH Niger site during the 2004-2007 rainy seasons. Many classical empirical methods of monsoon onset dectection (e.g. Benoit, Kowal, Sivakumar, Ati, Marteau, Balme, Sultan) and numerical methods based on crop model SARRAH have been compared to the observed farmer's sowing date. Results show that SARRAH and Balme mean onset date are close to sowing date. But spatial and temporal variability of the sow…

Lien entre démarrage de la saison des pluies et rendements agricoles observés/simulés du mil sur le site AMMA-CATCH.

International audience

What controls the early summer greenness in semi-arid South Africa?

Multi-scale study of the rainy season onset over the Sudano-Sahelian belt: Spatial coherence and potential predictability

The spatial coherence of boreal monsoon onset (July-September) over the western and central Sahel is studied through the analysis of daily rainfall records for 136 rain-gauges from 1950-2000. Onset of the rainy season has been defined using 3 definitions which rely on 3 overlapped spatial scales: (i) the regional scale, i.e. the northward ITCZ jump from Guinean to Soudano-Sahelian latitudes, (ii) the meso-scale related with the first occurrence of the main rainfall-generating phenomenon, that is squall line and (iii) the local-scale of the first rainfall recorded at the rain-gauge. Local and meso-scale onsets show a weak degree of instantaneous and inter-annual spatial coherence, meaning th…

Spatial coherence and potential predictability of intraseasonal descriptors of the rainy season in Soudano-Sahelian Africa : application to the pearl millet crop in Niamey area

The aim of this thesis is twofold : (i) fill a lack of knowledge about the spatial coherence and seasonal predictability of the intraseasonal characteristics (ISC) of the soudano-sahelian rainy season. These ISC are the seasonal rainfall amount (S), the daily rainfall frequency > 1 mm (O), the daily rainfall mean intensity (I), the dates of the onset and withdrawal of the rainy season, the mean length of the dry (LDS) and/or wet spells (LWS) ; (ii) document the climate-agriculture relationship over the Niamey area based on the millet crop example.From FRIEND-AOC daily rainfall records (1950-2000) for a 136 stations-network located in Senegal, Mali, Burkina-Faso and Niger, the spatial cohere…