Schefuss Enno, Schouten Stefan, Schneider Ralph R
DFG-Research Center Ocean Margins (RCOM) at the University of Bremen, Klagenfurter Strasse, 28359 Bremen, Germany.
Nature. 2005 Oct 13;437(7061):1003-6. doi: 10.1038/nature03945.
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. 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. Our knowledge of large-scale hydrological changes in equatorial Africa and their forcing factors is, however, limited. 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.
非洲过去的水文变化与各种气候过程有关，这取决于区域和时间尺度。受季风影响的非洲北部和南部地区的长期降水变化被认为受夏季日照岁差变化的控制。相反，北非热带地区的短期降水变化与北大西洋海表温度异常有关，影响了热带辐合带及其相关雨带的向北延伸。然而，我们对赤道非洲大规模水文变化及其驱动因素的了解有限。在这里，我们分析了从刚果河河口附近的一个海洋沉积岩芯中提取的陆源植物脂质的同位素组成，以便重建过去中非的降雨变化，并将这一记录与南大西洋的海表温度变化进行比较。我们发现，过去2万年中非的降水主要受南大西洋热带和亚热带之间海表温度差异的控制，而我们没有发现热带辐合带位置的变化对中非整体水分供应有重大影响的证据。我们得出结论，海洋环流的变化以及由此产生的海表温度模式在调节大气水分向中非大陆的输送方面很重要。
