Southward movement of the Pacific intertropical convergence zone AD 1400-1850
Southward movement of the Pacific intertropical convergence zone AD 1400-1850
复制标题
DOI：
10.1038/ngeo554
复制
发表时间：
2009-07-01
影响因子：
18.3
通讯作者：
Golubic, Stjepko
中科院分区：
文献类型：
--
作者：
Sachs, Julian P.;Sachse, Dirk;Golubic, Stjepko
热带降雨模式控制着超过10亿人的生存生活方式。这些降水模式的季节变化与热带辐合带位置的变化有关，其特征是夏季在北纬10度附近，冬季在北纬3度附近，深层对流导致强降水。对热带辐合带位置的动力控制存在争议，但来自亚洲、非洲和美洲大陆的古气候证据表明，热带辐合带在过去一千年中发生了重大变化，在小冰期（公元1400-1850年）的某个时间到达了最南端的位置。然而，由于没有太平洋热带辐合带气象核的记录，缺乏对其位置的定量约束。在这里，我们报告了来自北线群岛、加拉帕戈斯群岛和帕劳的湖泊沉积物的微生物学、分子和氢同位素证据，这些证据表明，在过去一千年的大部分时间里，太平洋热带辐合带在其现代位置的南部，在小冰期多达500公里。当时北半球较冷，可能是由于太阳辐照度较低，可能推动了热带辐合带向南。我们的结论是，地球辐射收支的微小变化可能深刻地影响热带降雨。
Tropical rainfall patterns control the subsistence lifestyle of more than one billion people. Seasonal changes in these rainfall patterns are associated with changes in the position of the intertropical convergence zone, which is characterized by deep convection causing heavy rainfall near 10 degrees N in boreal summer and 3 degrees N in boreal winter. Dynamic controls on the position of the intertropical convergence zone are debated, but palaeoclimatic evidence from continental Asia, Africa and the Americas suggests that it has shifted substantially during the past millennium, reaching its southernmost position some time during the Little Ice Age (AD 1400-1850). However, without records from the meteorological core of the intertropical convergence zone in the Pacific Ocean, quantitative constraints on its position are lacking. Here we report microbiological, molecular and hydrogen isotopic evidence from lake sediments in the Northern Line Islands, Galapagos and Palau indicating that the Pacific intertropical convergence zone was south of its modern position for most of the past millennium, by as much as 500 km during the Little Ice Age. A colder Northern Hemisphere at that time, possibly resulting from lower solar irradiance, may have driven the intertropical convergence zone south. We conclude that small changes in Earth's radiation budget may profoundly affect tropical rainfall.