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首页> 外文期刊>Global and planetary change >Surface-water Freshening: A Cause For The Onset Of North Pacific Stratification From 2.75 Ma Onward?
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Surface-water Freshening: A Cause For The Onset Of North Pacific Stratification From 2.75 Ma Onward?

机译：地表水新鲜化：是否是从2.75 Ma开始出现北太平洋分层的原因？

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摘要

Paleoceanographic data indicate a sudden stratification in the North Pacific Ocean around 2.75 Ma. Understanding the triggering mechanism for this sudden North Pacific stratification is one key to resolving forcing mechanisms for the Northern Hemisphere glaciation around 2.75 Ma, one of the most perplexing problems in paleoclimate research. The trigger for this sudden stratification has not been fully explored. Changes in deep-water or surface-water temperature and/or salinity can cause stratification. Here we re-examine paleoceanography data from the North Pacific Ocean and find evidence that the stratification was preceded by a surface-water salinity decrease between 2.83 and 2.75 Ma. This paleoceanographic result, in combination with recent model simulation results, suggests that fresh water input to the North Pacific via an intensified East Asian summer monsoon and/or an intensified Polar Westerly winter jet stream associated with a phase of accelerated uplift of the northeastern Tibetan Plateau from 4-2.6 Ma might be one important forcing for the onset of North Pacific stratification. Onset of North Pacific stratification around 2.75 Ma is closely related to the intensification of Northern Hemisphere glaciation around the same time via its effects on atmospheric CO_2 concentration and sea surface temperature seasonality. Forcing the onset of the North Pacific stratification and Northern Hemisphere glaciation via surface-water freshening has not been emphasized previously.
机译：古海洋学数据表明，北太平洋在2.75 Ma附近突然分层。了解这种北太平洋突然分层的触发机制是解决北半球冰期强迫机制的关键之一，该机制是古气候研究中最棘手的问题之一，约为2.75 Ma。这种突然分层的诱因尚未得到充分探索。深水或地表水温度和/或盐度的变化会导致分层。在这里，我们重新检查了北太平洋的古海洋学数据，发现有证据表明在分层之前，地表水盐度在2.83至2.75 Ma之间下降。该古海洋学结果与最近的模型仿真结果相结合，表明通过东亚夏季风的增强和/或北极西风冬季喷流的增强，北青藏高原东北部的加速隆升与淡水输入有关。从4-2.6 Ma开始可能是北太平洋分层开始的重要推动力。大约在2.75 Ma左右，北太平洋分层的发生与它对大气中CO_2浓度和海表温度季节性的影响密切相关，与北半球冰期的加剧密切相关。以前未曾强调过通过地表水新鲜化来强迫北太平洋分层和北半球冰川化。

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