Simulation of the cold climate event 8200 years ago by meltwater outburst from Lake Agassiz
Simulation of the cold climate event 8200 years ago by meltwater outburst from Lake Agassiz
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阿加西湖融水爆发模拟 8200 年前的寒冷气候事件
DOI：
10.1029/2004pa001030
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
M. Montoya
中科院分区：
文献类型：
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作者：
E. Bauer;A. Ganopolski;M. Montoya
根据Laurentide冰盖（LIS）消融的冰川学模拟，假定融水脉冲的体积为1.6 - 10 - 14立方米，流量周期为2年。我们提出了一个可能的机制，可以解释8.2 ka冷事件的百年持续时间。其机制与北大西洋深水（NADW）形成减少和NADW形成区南移的额外平衡气候状态的存在有关。在蒙特卡洛模拟中，脉冲引起的寒冷事件的持续时间变化很大，响应于叠加的随机淡水波动，由此获得了额外气候状态的线索。模式平衡状态是通过通过融水脉冲完成的圣劳伦斯通道释放微弱的多世纪淡水通量而达到的。这种气候模式的存在对于重现与8.2 ka事件古气候重建密切一致的气候异常是必不可少的。结果进一步表明，寒冷事件的时间演变在一定程度上是偶然的。索引项：3344气象学和大气动力学：古气候学；海洋学：一般：数值模拟；4532海洋学：物理：一般环流；4215海洋学：总论：气候和年际变化（3309）；9325地理区域相关信息：大西洋；
meltwater pulse is assumed to have a volume of 1.6 10 14 m 3 and a period of discharge of 2 years on the basis of glaciological modeling of the decay of the Laurentide Ice Sheet (LIS). We present a possible mechanism which can explain the centennial duration of the 8.2 ka cold event. The mechanism is related to the existence of an additional equilibrium climate state with reduced North Atlantic Deep Water (NADW) formation and a southward shift of the NADW formation area. Hints at the additional climate state were obtained from the largely varying duration of the pulse-induced cold episode in response to overlaid random freshwater fluctuations in Monte Carlo simulations. The model equilibrium state was attained by releasing a weak multicentury freshwater flux through the St. Lawrence pathway completed by the meltwater pulse. The existence of such a climate mode appears essential for reproducing climate anomalies in close agreement with paleoclimatic reconstructions of the 8.2 ka event. The results furthermore suggest that the temporal evolution of the cold event was partly a matter of chance. INDEX TERMS: 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 4255 Oceanography: General: Numerical modeling; 4532 Oceanography: Physical: General circulation; 4215 Oceanography: General: Climate and interannual variability (3309); 9325 Information Related to Geographic Region: Atlantic Ocean;