2009: The role of the Sahara Low in summertime Sahel rainfall variability and change in the CMIP3 models

• Main Authors: M. Biasutti, A. H. Sobel, Suzana J. Camargo, Short Title
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.599.7041; http://www.ldeo.columbia.edu/~biasutti/papers/Biasutti_Sobel_Camargo_JClim09_in_press.pdf

Projections for 21st century changes in summertime Sahel precipitation differ greatly across models in the CMIP3 dataset, and cannot be explained solely in terms of discrepancies in the projected anomalies in global SST. This study shows that an index describing the low-level circulation in the north Atlantic-African region, namely the strength of the low-level Saharan Low, correlates with Sahel rainfall in all models and at the timescales of both interannual/interdecadal natural variability, and of the forced centennial trend. An analysis of Sahel interannual variability provides evidence that variations in the Sahara Low can be a cause, not just a consequence, of variations in Sahel rainfall and suggests that a better understanding of the sources of model discrepancy in Sahel rainfall predictions might be gained from an analysis of the mechanisms influencing changes in the Sahara Low. As a global mean temperature increase in response to increasing atmospheric greenhouse gases becomes more certain (Meehl et al., 2007b), new challenges emerge: