The climate response of the Indo-Pacific warm pool to glacial sea level
The climate response of the Indo-Pacific warm pool to glacial sea level
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DOI：
10.1002/2015pa002890
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发表时间：
2016-06-01
期刊：
影响因子：
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通讯作者：
Montenegro, Alvaro
中科院分区：
文献类型：
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作者：
Di Nezio, Pedro N.;Timmermann, Axel;Montenegro, Alvaro
越来越多的气候代用证据表明，海平面的变化是冰川-间冰期时间尺度上热带气候变化的重要驱动因素。这些古数据表明，印度洋-太平洋暖池（IPWP）的降雨模式对海洋大陆的陆块配置高度敏感，海平面下降导致末次盛冰期（LGM，约21，000年B. P.）期间的大规模干燥。利用社区地球系统模式版本1.2（CESM 1），我们调查的机制，海平面下降影响IPWP的气候在末次盛冰期。CESM 1模拟表明，与以前的假设一致，大气环流的变化是由巽他和Sahul大陆架的暴露引起的。海洋动力过程通过增加沿赤道印度洋沿着的东西海表面温度梯度，放大了大气环流的变化。驱动这种反应的耦合机制类似于Bjerknes反馈，并导致印度洋大规模的气候重组，影响范围从东非延伸到热带太平洋西部。与Sunda陆架的暴露不同，Sahul陆架的暴露和相关的地表水变化确实发挥了关键作用，因为正反馈。这一机制可以解释在气候代用指标和末次冰期模拟中确定的东（西）印度洋干（湿）的格局。然而，这种反应也需要加强SST梯度沿着赤道印度洋，一种模式，是不明显的海洋古重建。解决这个问题的策略进行了讨论。
Growing climate proxy evidence suggests that changes in sea level are important drivers of tropical climate change on glacial-interglacial timescales. These paleodata suggest that rainfall patterns over the Indo-Pacific warm pool (IPWP) are highly sensitive to the landmass configuration of the Maritime Continent and that lowered sea level contributed to large-scale drying during the Last Glacial Maximum (LGM, approximately 21,000 years B.P.). Using the Community Earth System Model Version 1.2 (CESM1), we investigate the mechanisms by which lowered sea level influenced the climate of the IPWP during the LGM. The CESM1 simulations show that, in agreement with previous hypotheses, changes in atmospheric circulation are initiated by the exposure of the Sunda and Sahul shelves. Ocean dynamical processes amplify the changes in atmospheric circulation by increasing the east-west sea surface temperature (SST) gradient along the equatorial Indian Ocean. The coupled mechanism driving this response is akin to the Bjerknes feedback and results in a large-scale climatic reorganization over the Indian Ocean with impacts extending from east Africa to the western tropical Pacific. Unlike exposure of the Sunda shelf, exposure of Sahul shelf and the associated changes in surface albedo play a key role because of the positive feedback. This mechanism could explain the pattern of dry (wet) eastern (western) Indian Ocean identified in climate proxies and LGM simulations. However, this response also requires a strengthened SST gradient along the equatorial Indian Ocean, a pattern that is not evident in marine paleoreconstructions. Strategies to resolve this issue are discussed.