Intensification of the Walker and Hadley atmospheric circulations during the Pliocene-Pleistocene climate transition
Intensification of the Walker and Hadley atmospheric circulations during the Pliocene-Pleistocene climate transition
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DOI：
10.1016/j.epsl.2010.06.010
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发表时间：
2010-08
影响因子：
5.3
通讯作者：
J. Etourneau;R. Schneider;T. Blanz;P. Martinez
中科院分区：
文献类型：
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作者：
J. Etourneau;R. Schneider;T. Blanz;P. Martinez
对比赤道西太平洋和东赤道太平洋3.2 Ma以来的新海温记录，我们发现整个热带太平洋的纬向温度梯度从2.2 Ma到2.0 Ma不可逆转地增加了3~4℃。在这里，我们认为在早更新世，大气环流从弱到强的纬向沃克环流(WC)显著增加。来自其他海洋区域的证据也表明，在同一时期，经向哈德利环流(HC)有所加强。因此，我们还认为，这两种大气环流型的增强在上更新世过渡期间是密切耦合的，可能与热带到副热带暖球纬向延伸的收缩有关，与极地到赤道温度梯度的显著增加有关。我们的结论驳斥了热带和亚热带大气环流的加强对高纬度大陆冰盖形成的重要贡献的假设，因为北半球大范围冰川的开始发生在2.75 Ma之前，即上新世晚期。相反，2.2-2.0 Ma前更强的大气环流∼的发展可能对更新世-更新世气候变冷做出了重要贡献。
When comparing new sea surface temperature (SST) records between the western and eastern equatorial Pacific spanning the last 3.2Ma, we found that the zonal temperature gradient over the entire tropical Pacific irreversibly increased by 3 to 4°C from 2.2 to 2.0Ma. Here, we suggest a pronounced increase in atmospheric circulation from a weak to a strong zonal Walker circulation (WC) during the early Pleistocene. Evidence from other oceanic areas also suggests a strengthening in the meridional Hadley circulation (HC) during the same time period. Therefore, we also suggest that the invigoration of both atmospheric circulation patterns was intimately coupled during the Plio–Pleistocene transition, and likely linked to a shrinkage in the zonal extension of the tropical to subtropical warm-sphere associated with a prominent increase in the pole to equator temperature gradient. Our conclusion refutes assumptions that the intensification of atmospheric circulation in the tropics and subtropics significantly contributed to the initiation of continental ice sheet formation at high latitudes, since the onset of extensive Northern Hemisphere Glaciation (NHG) occurred ∼2.75Ma ago, in the late Pliocene. Instead, the development of a stronger atmospheric circulation ∼2.2–2.0Ma ago could have significantly contributed to the Plio–Pleistocene climate cooling.