Coupled High-Latitude Climate Feedbacks and Their Impact on Atmospheric Heat Transport
Coupled High-Latitude Climate Feedbacks and Their Impact on Atmospheric Heat Transport
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DOI：
10.1175/jcli-d-16-0324.1
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发表时间：
2017
影响因子：
4.9
通讯作者：
N. Feldl;S. Bordoni;T. Merlis
中科院分区：
文献类型：
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作者：
N. Feldl;S. Bordoni;T. Merlis
大气热量输送对人类活动增暖的响应取决于纬向能量梯度的异常。反馈分析提供了梯度的特征，从而揭示了物理过程中的不确定性如何转化为环流响应中的不确定性。然而，个人反馈并不是孤立的。与一种反馈相关的异常可能会被另一种反馈所补偿，就像热带地区的正水汽和负直减率反馈一样。在这里，一组理想化的实验进行了一个aquaplanet模式，以评估之间的耦合表面的反馈和其他反馈，包括对大气热传输的影响。在热带，动力响应表现为翻转的Hadley环流的强度和结构的变化。在这些实验中，只有一半的哈德利细胞减弱的范围被认为是由于表面反馈的系统性变化。伴随着对流层变化的对流层外云的变化解释了剩余的扩散。反馈驱动的环流变化由涡流能通量变化补偿，这减少了实验之间的总体传播。这些发现对包括热带环流和水文循环在内的气候系统适应高纬度气候状态反馈的效率具有影响，这些气候状态从常年或季节性冰到北极的无冰条件。
The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic.