Thermodynamic control of anvil cloud amount
Thermodynamic control of anvil cloud amount
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DOI：
10.1073/pnas.1601472113
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发表时间：
2016-08-09
影响因子：
11.1
通讯作者：
Medeiros, Brian
中科院分区：
文献类型：
--
作者：
Bony, Sandrine;Stevens, Bjorn;Medeiros, Brian
大气环流模式显示，随着地面温度的升高，对流砧云收缩。通过分析辐射对流平衡模拟，我们表明，这种行为是植根于基本的能量和热力学性质的大气：随着气候变暖，云上升，并保持在几乎相同的温度，但发现自己在一个更稳定的大气，这种增强的稳定性减少对流层上层的对流流出，并减少砧云的分数。通过加热对流层和增加对流层上层的稳定性，深对流的聚集也减少了对流流出和砧云分数。当云辐射活跃时，温度、高云和环流之间的这种强耦合对对流聚集产生正反馈，并有利于在高温下维持强聚集的大气状态。随着气候变暖，这种稳定性虹膜机制可能有助于缩小多雨区域。它是否影响气候敏感性需要进一步调查。
General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative-convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climatewarms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.