AMMA-CATCH studies in the Sahelian region of West-Africa: An overview

Abstract

The main objectives of this paper are: (i) to present the rationale for maintaining a long term hydrometeorological observing system in West Africa ; (ii) to review the state of the art regarding our knowledge on the land-atmosphere interactions in this region and the main scientific questions to address in order to improve our understanding of these interactions; (iii) to present the observational strategy of this long term observing system; and finally iv) the paper describes the scope and content of the special issue. As present, 18 papers are accepted for publication in the special issue, 6 are in final form, 12 others were accepted pending minor of moderate revision (written in green in the scope and content section and in the list of references); one is still undergoing revision of the re-submitted version (written in red in the scope and content section). Given the time needed for reviewing a paper and in order not to delay the final publication of the special issue, this overview paper is submitted now, since it is considered that the papers accepted pending minor of moderate revision, will indeed be included in the special issue. We thank you very much for considering this manuscript for the special issue.

On the spatial coherence of rainfall over the Saloum delta (Senegal) from seasonal to decadal time scales

“…Their methods are aimed at assessing the natural variability of the WAM over long periods. However, such generalization may deserve some care since precipitations are known to have patchy features with small spatial scale (Houze and Cheng, 1977;Leary and Houze, 1979;Nicholson, 1995;Chen et al, 1996;Rickenbach and Rutledge, 1998;Lebel et al, 2009). In this study, we show how the local Saloum rainfall is coherent with the regional Sahel rainfall at seasonal to decadal time scales.…”

“…While their work opens stimulating perspectives for the investigation of the seasonality of the WAM in the past, the relationship between local and regional rainfall variability needs to be assessed before extending paleoclimate reconstructions in the Saloum to the WAM in general. Precipitation is indeed known to be a patchy feature with small spatial scale (e.g., Houze and Cheng, 1977;Leary and Houze, 1979;Nicholson, 1995;Chen et al, 1996;Rickenbach and Rutledge, 1998;Lebel et al, 2009).…”

“…Fontaine and Janicot (1996) later simplified this classification as they found that the western and continental Sahel rainfall anomalies were of the same sign for the majority of stations they analyzed. More recently, east-west contrasts have also been noted at decadal timescales (Dieppois et al, 2013) as well as at longer timescales, related to the long-term trends in response to climatic forcing (e.g., Lebel et al, 2009;Monerie et al, 2012;Biasutti, 2013).…”

A review of droughts on the African continent: a geospatial and long-term perspective

“…Clarke et al, 2012;Cornforth, 2013;Dube and Jury, 2000Green, 1993;Jager et al, 1998;Manatsa et al, 2008;O'Meagher et al, 1998;Richard et al, 2001;Unganai and Kogan, 1998;Vogel et al, 2010), Sahel (western Africa) (e.g. Giannini et al, 2008;Govaerts and Lattanzio, 2008;Kasei et al, 2010;Lebel et al, 2009;Lodoun et al, 2013;Traore and Fontane, 2007;Zeng, 2003), eastern Africa (Horn of Africa) (e.g. Anderson et al, 2012;Syroka and Nucifora, 2010) and northwestern Africa (e.g.…”

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

“…This high hydric deficit, which was never known in West Africa in the past, had severe impacts on agricultural activities and vegetation development due likely to its spatial extent and temporal continuity (IPCC 2013). In the West Africa region, the climate is strongly controlled by the West African Monsoon (WAM), but with significant differences related to the variability of precipitation between Sahelian and Sudanian regions as reported by several authors (Lebel et al 2009;Nicholson 2013). Consequently, most ecosystems (anthropogenic and natural) may be significantly modified in the context of climate change and high population growth in West Africa (IPCC 2013;Ajonina et al 2014).…”