Asian monsoon evolution linked to Pacific temperature gradients since the Late Miocene
Asian monsoon evolution linked to Pacific temperature gradients since the Late Miocene
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DOI：
10.1016/j.epsl.2021.116882
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发表时间：
2021-06
影响因子：
5.3
通讯作者：
Jiayi Lu;Huan Yang;M. Griffiths;N. Burls;G. Xiao;Jilong Yang;J. K. Wang;K. Johnson;S. Xie
中科院分区：
文献类型：
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作者：
Jiayi Lu;Huan Yang;M. Griffiths;N. Burls;G. Xiao;Jilong Yang;J. K. Wang;K. Johnson;S. Xie
自中新世晚期以来，东亚季风演化的性质和原因仍然存在相当大的不确定性，这是一个明显变暖的时期，其特点是经向和纬向太平洋海面温度（SST）梯度比今天弱得多，因此被视为当前和未来全球变暖的潜在类比。然而，这些温度梯度在多大程度上影响整个东亚地区的降雨模式，特别是季风区的北部范围，仍然存在争议。在这里，我们展示了华北平原第一个可追溯到八百万年前（Ma）的水文记录，该记录源自陆地沉积物序列中保存的有机生物标记。我们的记录显示，上新世早期（∼4.2-4.5 Ma）季风降雨显着增加，与太平洋经向和纬向海温梯度以及赤道东太平洋冷舌的加强相一致。南亚的古气候档案中也观察到了中国北方季风降雨的显着增强，但与中国中东部（包括华南）的情况相反，表明东亚地区出现了“三极状”降雨模式。通过一系列气候模型实验，我们表明，上新世早期（5.33-3.6 Ma）整个东亚季风降雨的重新分配可能是由于西太平洋暖池向赤道收缩、西副热带太平洋夏季对流减少以及哈德利和沃克环流的加强所致。因此，我们的研究强调了太平洋温度梯度对东亚水文气候的强烈影响。
Considerable uncertainty remains over the nature and causes(s) of East Asian monsoon evolution since the Late Miocene, a significantly warmer period characterized by substantially weaker meridional and zonal Pacific sea surface temperature (SST) gradients than today and therefore regarded as a potential analog for current and future global warming. However, the extent to which these temperature gradients impacted rainfall patterns across East Asia, and particularly the northern extent of the monsoon domain, remains controversial. Here we present the first hydrological record extending back eight million years (Ma) for North China Plain derived from organic biomarkers preserved in a terrestrial sediment sequence. Our record shows a significant increase in monsoon rainfall during the Early Pliocene (∼4.2-4.5 Ma), coincident with strengthening of Pacific meridional and zonal SST gradients, and the eastern equatorial Pacific cold tongue. This marked intensification of the monsoon rainfall in northern China is also observed in paleoclimate archives from southern Asia, but anti-phased with those from central-eastern China (including southern China), indicating a ‘tripole-like’ rainfall pattern over East Asia. Through a set of climate model experiments, we show that this redistribution of monsoon rainfall across East Asia during the Early Pliocene (5.33-3.6 Ma) was likely due to an equatorward contraction of the western Pacific warm pool, reduced summer convection in the western subtropical Pacific, and the strengthening of the Hadley and Walker circulations. Our study thus highlights the strong influence of Pacific Ocean temperature gradients on East Asian hydroclimate.