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Sources of Sahelian-Sudan moisture: Insights from a moisture-tracing atmospheric model
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Physical Geography.
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Meteorology .
Number of Authors: 4
2016 (English)In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 121, no 13, 7819-7832 p.Article in journal (Refereed) Published
Abstract [en]

The summer rainfall across Sahelian-Sudan is one of the main sources of water for agriculture, human, and animal needs. However, the rainfall is characterized by large interannual variability, which has attracted extensive scientific efforts to understand it. This study attempts to identify the source regions that contribute to the Sahelian-Sudan moisture budget during July through September. We have used an atmospheric general circulation model with an embedded moisture-tracing module (Community Atmosphere Model version 3), forced by observed (1979-2013) sea-surface temperatures. The result suggests that about 40% of the moisture comes with the moisture flow associated with the seasonal migration of the Intertropical Convergence Zone (ITCZ) and originates from Guinea Coast, central Africa, and the Western Sahel. The Mediterranean Sea, Arabian Peninsula, and South Indian Ocean regions account for 10.2%, 8.1%, and 6.4%, respectively. Local evaporation and the rest of the globe supply the region with 20.3% and 13.2%, respectively. We also compared the result from this study to a previous analysis that used the Lagrangian model FLEXPART forced by ERA-Interim. The two approaches differ when comparing individual regions, but are in better agreement when neighboring regions of similar atmospheric flow features are grouped together. Interannual variability with the rainfall over the region is highly correlated with contributions from regions that are associated with the ITCZ movement, which is in turn linked to the Atlantic Multidecadal Oscillation. Our result is expected to provide insights for the effort on seasonal forecasting of the rainy season over Sahelian Sudan.

Place, publisher, year, edition, pages
2016. Vol. 121, no 13, 7819-7832 p.
Keyword [en]
Sahel, Sudan, rainfall, moisture sources, moisture tagging, rainfall variability
National Category
Meteorology and Atmospheric Sciences
URN: urn:nbn:se:su:diva-134287DOI: 10.1002/2015JD024575ISI: 000380730500019OAI: diva2:1033091
Available from: 2016-10-05 Created: 2016-10-03 Last updated: 2016-10-05Bibliographically approved

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Zhang, QiongPausata, Francesco S. R.Tjernström, Michael
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