On the stability of the Atlantic meridional overturning circulation
On the stability of the Atlantic meridional overturning circulation
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DOI：
10.1073/pnas.0909146106
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发表时间：
2009-12-08
影响因子：
11.1
通讯作者：
Rahmstorf, Stefan
中科院分区：
文献类型：
--
作者：
Hofmann, Matthias;Rahmstorf, Stefan
对地球气候影响最大的大尺度洋流系统之一是大西洋纬向翻转环流（AMOC）。在这里，我们回顾其稳定性和提出新的模型模拟研究的AMOC的滞后响应淡水扰动。我们采用了七个不同版本的海洋环流模式，通过使用一个高精度的示踪平流方案，最大限度地减少了数值扩散的问题。我们发现，一个特征淡水滞后也存在于主要是风力驱动，低扩散的AMOC限制。然而，形状的滞后变化，表明对流不稳定，而不是平流Stommel反馈起着主导作用。我们发现，在平均气候的模型误差可以使滞后消失，我们调查如何在过去的二十年中，如新的参数化和混合方案的模型创新，影响AMOC的稳定性。最后，我们讨论的证据表明，目前的气候模型系统高估了AMOC的稳定性。
One of the most important large-scale ocean current systems for Earth`s climate is the Atlantic meridional overturning circulation (AMOC). Here we review its stability properties and present new model simulations to study the AMOC's hysteresis response to freshwater perturbations. We employ seven different versions of an Ocean General Circulation Model by using a highly accurate tracer advection scheme, which minimizes the problem of numerical diffusion. We find that a characteristic freshwater hysteresis also exists in the predominantly wind-driven, low-diffusion limit of the AMOC. However, the shape of the hysteresis changes, indicating that a convective instability rather than the advective Stommel feedback plays a dominant role. We show that model errors in the mean climate can make the hysteresis disappear, and we investigate how model innovations over the past two decades, like new parameterizations and mixing schemes, affect the AMOC stability. Finally, we discuss evidence that current climate models systematically overestimate the stability of the AMOC.