文章基本信息

标题：Low cloud reduction in a greenhouse‐warmed climate: Results from Lagrangian LES of a subtropical marine cloudiness transition
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作者：Christopher S. Bretherton ; Peter N. Blossey
期刊名称：Journal of Advances in Modeling Earth Systems
电子版ISSN：1942-2466
出版年度：2014
卷号：6
期号：1
页码：1-24
DOI：10.1002/2013MS000250
出版社：John Wiley & Sons, Ltd.
摘要：Lagrangian large‐eddy simulations of a composite stratocumulus to cumulus transition case over the subtropical northeast Pacific Ocean are subject to perturbed forcings that isolate the cloud response to CO2, to overall tropical warming, and to increased inversion stability over the subtropical subsidence regions. These simulations show that a tropical surface warming of 4 K induces substantial stratocumulus thinning via a thermodynamic mechanism: increased cloud layer humidity flux in a warmer climate induces an entrainment liquid‐flux adjustment that dries the stratocumulus cloud layer, whether well mixed or cumulus coupled. A radiative mechanism amplifies this response: increased emissivity of the free troposphere due to increased CO2 and water vapor reduces radiative driving of turbulence in a stratocumulus‐capped boundary layer; a thinner stratocumulus layer accompanies less turbulence. In combination, a 4 K warming and CO2 quadrupling greatly reduce low cloud and weaken the simulated shortwave cloud radiative effect by over 50%. Large increases in inversion stability in the stratocumulus regions could counter much of this cloudiness reduction.
关键词：cloud feedbacks;Large‐Eddy Simulation;boundary‐layer clouds