Multi-centennial variability controlled by Southern Ocean convection in the Kiel Climate Model
Multi-centennial variability controlled by Southern Ocean convection in the Kiel Climate Model
复制标题
基尔气候模型中南大洋对流控制的百年变率
DOI：
10.1007/s00382-012-1586-7
复制
发表时间：
2013
期刊：
影响因子：
4.6
通讯作者：
M. Latif
中科院分区：
文献类型：
--
作者：
T. Martin;W. Park;M. Latif
描述了基尔气候模型中南大洋大西洋部分的准振荡百年深对流模式。深对流的准周期性发生导致区域和全球表面气温、南半球海冰覆盖、南大洋和北大西洋海面高度、南极绕极流和大西洋经向翻转环流（AMOC）的变化。深层对流是由中深度强烈积聚的热量刺激的。当热库几乎耗尽时，海面同时发生的强烈清新事件会关闭对流。热量来自北大西洋形成的相对温暖的深水。热库持续数十年的补给过程取决于 AMOC 和威德尔环流，并设定了深层对流再次发生的最小延迟。在非对流状态下，虽然 AMOC 的强度增加，但威德尔环流却减弱。对流的开始和结束还取决于有利海面条件的随机发生，这导致了这种现象长达数百年之久。此次关闭引发了 AMOC 强度长达一个世纪的偏差，这是由于南大洋大西洋部分的底水形成和表面盐度显着减少造成的。额外的数值实验表明，海冰对深对流的发生频率和强度有重要影响。此外，我们还发现与 20 世纪 70 年代观测到的威德尔冰间湖有有趣的相似之处。
A quasi-oscillatory multi-centennial mode of open ocean deep convection in the Atlantic sector of the Southern Ocean in the Kiel Climate Model is described. The quasi-periodic occurrence of the deep convection causes variations in regional and global surface air temperature, Southern Hemisphere sea ice coverage, Southern Ocean and North Atlantic sea surface height, the Antarctic Circumpolar Current and the Atlantic Meridional Overturning Circulation (AMOC). The deep convection is stimulated by a strong built-up of heat at mid-depth. When the heat reservoir is virtually depleted a coincidental strong freshening event at the sea surface shuts down the convection. The heat originates from relatively warm deep water formed in the North Atlantic. The several decades lasting recharge process of the heat reservoir depends on the AMOC and the Weddell Gyre and sets a minimum delay for the deep convection to recur. While the strength of the AMOC increases, the Weddell Gyre weakens during the non-convective regime. Convection onset and shutdown also depend on the stochastic occurrence of favorable sea surface conditions, which contributes to the multi-centennial period of the phenomenon. The shutdown triggers a century-long deviation in AMOC strength caused by significant reductions in bottom water formation and surface salinity in the Southern Ocean’s Atlantic sector. Additional numerical experimentation reveals that sea ice has an important effect on the frequency of occurrence and intensity of the deep convection. Further, we find intriguing similarities to the Weddell Polynya observed during the 1970s.