Indian monsoon variations during three contrasting climatic periods: The Holocene, Heinrich Stadial 2 and the last interglacial–glacial transition
Indian monsoon variations during three contrasting climatic periods: The Holocene, Heinrich Stadial 2 and the last interglacial–glacial transition
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DOI：
10.1016/j.quascirev.2015.06.009
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发表时间：
2015-10
影响因子：
4
通讯作者：
Coralie Zorzi;M. F. S. Goñi;K. Anupama;S. Prasad;V. Hanquiez;Joel E. Johnson;L. Giosan
中科院分区：
文献类型：
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作者：
Coralie Zorzi;M. F. S. Goñi;K. Anupama;S. Prasad;V. Hanquiez;Joel E. Johnson;L. Giosan
与东亚和非洲季风相比，印度季风在上一个气候周期(过去135,000年)中的记录仍然很少。从位于核心季风带(CMZ)的近海Godavari和Mahanadi盆地采集的两个海洋沉积物岩芯(NGHP-01-16A和NGHP-01-19B)的花粉分析显示，印度夏季风在三个不同的气候阶段：全新世、海因里希阶梯(HS)2和海洋同位素阶段(MIS)5/4的冰盖生长过渡期间发生了变化。在全新世第一部分(11300~4200年BP)，以高日照(最小进动，最大倾角)为特征，沿海森林和红树林的最大伸展反映了高季风降水。这一气候制度与全新世第二阶段的气候制度形成了对比，从4200年前到现在，以低日照(最大进动，最小倾角)背景下较干燥的植被发育为标志。印度的历史时期以强季风和弱季风的百年交替为特征，这可能分别反映了中世纪气候异常和小冰期。在北大西洋低日照和大范围冰山排放的HS 2期间，由于印度夏季风的减弱，植被以草原和干燥的植物为主，表明明显的干旱。MIS5/4冰期的特征是印度夏季风减弱较弱，季节反差减小，表现为干燥植被的扩张和蒿属植物的发育。我们的结果支持模式预测，即日照变化控制着印度季风降水的长期趋势，但其千年尺度的变异性和强度却受到北大西洋、欧亚或印度洋偏远现象的大气遥相关的调制。
In contrast to the East Asian and African monsoons the Indian monsoon is still poorly documented throughout the last climatic cycle (last 135,000 years). Pollen analysis from two marine sediment cores (NGHP-01-16A and NGHP-01-19B) collected from the offshore Godavari and Mahanadi basins, both located in the Core Monsoon Zone (CMZ) reveals changes in Indian summer monsoon variability and intensity during three contrasting climatic periods: the Holocene, the Heinrich Stadial (HS) 2 and the Marine Isotopic Stage (MIS) 5/4 during the ice sheet growth transition. During the first part of the Holocene between 11,300 and 4200 cal years BP, characterized by high insolation (minimum precession, maximum obliquity), the maximum extension of the coastal forest and mangrove reflects high monsoon rainfall. This climatic regime contrasts with that of the second phase of the Holocene, from 4200 cal years BP to the present, marked by the development of drier vegetation in a context of low insolation (maximum precession, minimum obliquity). The historical period in India is characterized by an alternation of strong and weak monsoon centennial phases that may reflect the Medieval Climate Anomaly and the Little Ice Age, respectively. During the HS 2, a period of low insolation and extensive iceberg discharge in the North Atlantic Ocean, vegetation was dominated by grassland and dry flora indicating pronounced aridity as the result of a weak Indian summer monsoon. The MIS 5/4 glaciation, also associated with low insolation but moderate freshwater fluxes, was characterized by a weaker reduction of the Indian summer monsoon and a decrease of seasonal contrast as recorded by the expansion of dry vegetation and the development ofArtemisia, respectively. Our results support model predictions suggesting that insolation changes control the long term trend of the Indian monsoon precipitation, but its millennial scale variability and intensity are instead modulated by atmospheric teleconnections to remote phenomena in the North Atlantic, Eurasia or the Indian Ocean.