Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.1175/JAS-D-16-0196.1 |
Reduction of the Entrainment Velocity by Cloud Droplet Sedimentation in Stratocumulus | |
de Lozar, Alberto; Mellado, Juan Pedro | |
2017-03-01 | |
发表期刊 | JOURNAL OF THE ATMOSPHERIC SCIENCES
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ISSN | 0022-4928 |
EISSN | 1520-0469 |
出版年 | 2017 |
卷号 | 74期号:3 |
文章类型 | Article |
语种 | 英语 |
国家 | Germany |
英文摘要 | The effect of sedimentation on stratocumulus entrainment is investigated using direct numerical simulations of a cloud-top mixing layer driven by radiative and evaporative cooling. The simulations focus on the meter and submeter scales that are expected to be relevant for entrainment, and the finest grid spacing is Delta x = 26 cm. The entrainment velocity is investigated from the analysis of the integrated-buoyancy evolution equation, which is exactly derived from the flow evolution equations. The analysis shows that sedimentation interacts with entrainment through two different mechanisms. As previously reported, sedimentation prevents droplets from evaporating in the entrainment zone, which in turn reduces the entrainment velocity. Here it is shown that sedimentation also promotes a positive buoyancy flux that directly opposes entrainment. The strengths of both mechanisms are characterized by two different settling numbers, which allow for predicting which meteorological conditions favor the reduction of entrainment by sedimentation. These new insights allow for including sedimentation in a parameterization of the entrainment velocity. The reduction of the entrainment velocity by sedimentation predicted by the parameterization and observed in the simulations is 3 times larger than previously reported in large-eddy simulations, which implies that meter-and submeter-scale turbulence plays an important role in the interaction of entrainment with sedimentation. On the whole, analysis and simulations indicate that stratocumulus entrainment is more sensitive to the cloud droplet number density due to sedimentation than previously thought. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000399332300002 |
WOS关键词 | NOCTURNAL MARINE STRATOCUMULUS ; LARGE-EDDY SIMULATIONS ; TOPPED MIXED LAYERS ; BOUNDARY-LAYER ; DIURNAL CYCLE ; AEROSOLS ; FORMULA ; IMPACT ; MODEL |
WOS类目 | Meteorology & Atmospheric Sciences |
WOS研究方向 | Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/29738 |
专题 | 地球科学 |
作者单位 | Max Plank Inst Meteorol, Hamburg, Germany |
推荐引用方式 GB/T 7714 | de Lozar, Alberto,Mellado, Juan Pedro. Reduction of the Entrainment Velocity by Cloud Droplet Sedimentation in Stratocumulus[J]. JOURNAL OF THE ATMOSPHERIC SCIENCES,2017,74(3). |
APA | de Lozar, Alberto,&Mellado, Juan Pedro.(2017).Reduction of the Entrainment Velocity by Cloud Droplet Sedimentation in Stratocumulus.JOURNAL OF THE ATMOSPHERIC SCIENCES,74(3). |
MLA | de Lozar, Alberto,et al."Reduction of the Entrainment Velocity by Cloud Droplet Sedimentation in Stratocumulus".JOURNAL OF THE ATMOSPHERIC SCIENCES 74.3(2017). |
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