How does the Redi parameter for mesoscale mixing impact global climate in an Earth System Model?
How does the Redi parameter for mesoscale mixing impact global climate in an Earth System Model?
复制标题
中尺度混合的 Redi 参数如何影响地球系统模型中的全球气候？
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Gnanadesikan
中科院分区：
文献类型：
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作者：
M. Pradal;A. Gnanadesikan
一个耦合的气候模式被用来研究由于中尺度涡旋的混合增加对全球气候系统的影响。Redi混合系数ARedi增加六倍，在允许的变化范围内，总体上会使全球平均表面空气和海洋表面温度升高1°C以上。在局部地区，北太平洋的海面温度上升了7°C，南大洋上升了4°C，对极地地区的冰密度和冰的范围产生了相应的影响。然而，目前还不清楚，从热带到极地的热传输的变化与改变这个系数是主要负责这些变化。我们发现，热量传输的变化通常比长波捕获和短波吸收的变化小得多。此外，热量向两极的平流和扩散输送的变化往往是相反的。然而，我们注意到，盐的极向运输增加表面附近的ARedi增加。我们提出了一个因果链，其中增强的涡流搅拌导致高纬度表面盐度增加，减少盐分层和水柱稳定性，并增强对流，触发两个反馈回路。在一个，更深的对流防止海冰形成，这减少了对流，这增加了西南吸收，进一步增加SST和减少海冰形成。另一方面，SST增加和海冰减少使大气中有更多的水蒸气，捕获长波辐射。因此，破坏极地地区是海洋环流变化可能使地球变暖的一种潜在方式。
A coupled climate model is used to examine the impact of an increase in the mixing due to mesoscale eddies on the global climate system. A sixfold increase in the Redi mixing coefficient ARedi, which is within the admissible range of variation, has the overall effect of warming the global‐mean surface air and sea surface temperatures by more than 1°C. Locally, sea surface temperatures increase by up to 7°C in the North Pacific and by up to 4°C in the Southern Ocean, with corresponding impacts on the ice concentration and ice extent in polar regions. However, it is not clear that the changes in heat transport from tropics to poles associated with changing this coefficient are primarily responsible for these changes. We found that the changes in the transport of heat are often much smaller than changes in long‐wave trapping and short‐wave absorption. Additionally, changes in the advective and diffusive transport of heat toward the poles often oppose each other. However, we note that the poleward transport of salt increases near the surface as ARedi increases. We suggest a causal chain in which enhanced eddy stirring leads to increased high‐latitude surface salinity reducing salt stratification and water column stability and enhancing convection, triggering two feedback loops. In one, deeper convection prevents sea ice formation, which decreases albedo, which increases SW absorption, further increasing SST and decreasing sea ice formation. In the other, increased SST and reduced sea ice allow for more water vapor in the atmosphere, trapping long‐wave radiation. Destratifying the polar regions is thus a potential way in which changes in ocean circulation might warm the planet.
影响因子：
4.3
作者：
Jungclaus, J. H.;Lorenz, S. J.;Marotzke, J.
通讯作者：
Marotzke, J.