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Forcing of wet phases in southeast Africa over the past 17,000 years

机译：过去17,000年非洲东南部的湿相强迫

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Intense debate persists about the climatic mechanisms governing hydrologic changes in tropical and subtropical southeast Africa since the Last Glacial Maximum, about 20,000 years ago. In particular, the relative importance of atmospheric and oceanic processes is not firmly established. Southward shifts of the intertropical convergence zone (ITCZ) driven by high-latitude climate changes have beeh suggested as a primary forcing, whereas other studies infer a predominant influence of Indian Ocean sea surface temperatures on regional rainfall changes. To address this question, a continuous record representing an integrated signal of regional climate variability is required, but has until now been missing. Here we show that remote atmospheric forcing by cold events in the northern high latitudes appears to have been the main driver of hydro-climatology in southeast Africa during rapid climate changes over the past 17,000 years. Our results are based on a reconstruction of precipitation and river discharge changes, as recorded in a marine sediment core off the mouth of the Zambezi River, near the southern boundary of the modern seasonal ITCZ migration. Indian Ocean sea surface temperatures did not exert a primary control over southeast African hydrologic variability. Instead, phases of high precipitation and terrestrial discharge occurred when the ITCZ was forced southwards during Northern Hemisphere cold events, such as Heinrich stadial 1 (around 16,000 years ago) and the Younger Dryas (around 12,000 years ago), or when local summer insolation was high in the late Holocene, that is, during the past 4,000 years.
机译：自大约20,000年前的上一次冰河最高峰以来，关于控制热带和亚热带东南非洲水文变化的气候机制的争论一直很激烈。特别是，大气和海洋过程的相对重要性尚未得到牢固确立。在高纬度气候变化的推动下，热带辐合带（ITCZ）向南移动被认为是主要的强迫，而其他研究则推断印度洋海表温度对区域降雨变化具有主要影响。为了解决这个问题，需要连续的记录来表示区域气候变化的综合信号，但是迄今为止一直没有。在这里，我们表明，在过去17,000年的快速气候变化过程中，北部高纬度地区由于寒冷事件引起的偏远大气强迫似乎已经成为东南非洲水文气候学的主要驱动力。我们的结果基于对降水和河流流量变化的重建，正如在ITCZ季节性迁徙的南部边界附近的赞比西河河口附近的海洋沉积岩心中所记录的那样。印度洋海表温度并未对南非东南部的水文变异起主要控制作用。相反，当ITCZ在北半球寒冷事件（例如Heinrich stadial 1（大约16,000年前）和Younger Dryas（大约12,000年前））期间被迫向南移动时，或者当当地夏天发生日晒时，发生了高降水和地面放电的阶段。在全新世晚期（即过去的4,000年）中处于较高水平。

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  • 来源
    《Nature》 |2011年第7378期|p.509-512|共4页
  • 作者

    Enno Schefuss; rnHolger Kuhlmann; rnGesine Mollenhauer; rnMatthias Prange; rnJuergen Paetzold;

  • 作者单位

    MARUM-Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, D-28359 Bremen, Germany;

    MARUM-Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, D-28359 Bremen, Germany;

    MARUM-Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, D-28359 Bremen, Germany,Alfred Wegener Institute for Polar and Marine Research, D-27568 Bremerhaven, Germany;

    MARUM-Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, D-28359 Bremen, Germany;

    MARUM-Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, D-28359 Bremen, Germany;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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