Age model, isotope analyses, geochemical measurements and grain size analyses of sediment core GeoB9508-5 from the Senegal River Mouth

The influence of the large-scale ocean circulation on Sahel rainfall is elusive because of the shortness of the observational record. We reconstructed the history of eolian and fluvial sedimentation on the continental slope off Senegal during the past 57,000 years. Our data show that abrupt onsets of arid conditions in the West African Sahel were linked to cold North Atlantic sea surface temperatures during times of reduced meridional overturning circulation associated with Heinrich Stadials. Climate modeling suggests that this drying is induced by a southward shift of the West African monsoon trough in conjunction with an intensification and southward expansion of the midtropospheric African Easterly Jet.由于观测记录时长有限，大规模海洋环流对萨赫勒（Sahel）地区降水的影响迄今仍难以厘清。本研究重建了过去57000年间塞内加尔外海大陆坡上的风成与河流相沉积演化历史。研究数据表明，西非萨赫勒地区突发干旱事件的出现，与海因里希冷期（Heinrich Stadials）期间经向翻转环流（meridional overturning circulation）减弱时北大西洋海表温度偏低存在显著关联。气候模拟结果显示，此次干旱事件由西非季风槽南移，叠加对流层中层非洲东风急流（African Easterly Jet）的增强与南扩共同驱动。