Climatic controls on central African hydrology during the past 20,000 years
Climatic controls on central African hydrology during the past 20,000 years
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DOI：
10.1038/nature03945
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发表时间：
2005-10-13
期刊：
影响因子：
64.8
通讯作者：
Schneider, RR
中科院分区：
文献类型：
--
作者：
Schefuss, E;Schouten, S;Schneider, RR
非洲过去的水文变化与不同区域和时间尺度的各种气候过程有关。受季风影响的北方和南部非洲地区的长期降水变化被认为是由夏季日照岁差变化所控制的（1，2）。相反，北方非洲热带地区的短期降水变化与北大西洋海面温度异常有关，影响了热带辐合带及其相关雨带的北向延伸（3，4）。然而，我们对赤道非洲大规模水文变化及其强迫因素的了解有限（5）。在这里，我们分析了陆源植物脂质的同位素组成，提取的海洋沉积物核心靠近刚果河口，以重建过去的中非降雨量的变化，并比较这一记录在南大西洋的海面温度变化。我们发现，在过去的20,000年中非降水主要是由南大西洋的热带和亚热带之间的海面温度的差异控制，而我们没有发现证据表明热带辐合带的位置的变化有显着的影响在中部非洲的整体水分供应。我们的结论是，海洋环流的变化，因此海表温度模式，是重要的调制大气水分输送到中非大陆。
Past hydrological changes in Africa have been linked to various climatic processes, depending on region and timescale. Long-term precipitation changes in the regions of northern and southern Africa influenced by the monsoons are thought to have been governed by precessional variations in summer insolation(1,2). Conversely, short-term precipitation changes in the northern African tropics have been linked to North Atlantic sea surface temperature anomalies, affecting the northward extension of the Intertropical Convergence Zone and its associated rainbelt(3,4). Our knowledge of large-scale hydrological changes in equatorial Africa and their forcing factors is, however, limited(5). Here we analyse the isotopic composition of terrigenous plant lipids, extracted from a marine sediment core close to the Congo River mouth, in order to reconstruct past central African rainfall variations and compare this record to sea surface temperature changes in the South Atlantic Ocean. We find that central African precipitation during the past 20,000 years was mainly controlled by the difference in sea surface temperatures between the tropics and subtropics of the South Atlantic Ocean, whereas we find no evidence that changes in the position of the Intertropical Convergence Zone had a significant influence on the overall moisture availability in central Africa. We conclude that changes in ocean circulation, and hence sea surface temperature patterns, were important in modulating atmospheric moisture transport onto the central African continent.