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DOI | 10.1175/JAS-D-18-0027.1 |
Wind Shear Effects on Radiatively and Evaporatively Driven Stratocumulus Tops | |
Schulz, Bernhard; Mellado, Juan Pedro | |
2018-09-01 | |
发表期刊 | JOURNAL OF THE ATMOSPHERIC SCIENCES |
ISSN | 0022-4928 |
EISSN | 1520-0469 |
出版年 | 2018 |
卷号 | 75期号:9页码:3245-3263 |
文章类型 | Article |
语种 | 英语 |
国家 | Germany |
英文摘要 | Direct numerical simulations resolving meter and submeter scales in the cloud-top region of stratocumulus are used to investigate the interactions between a mean vertical wind shear and in-cloud turbulence driven by evaporative and radiative cooling. There are three major results. First, a critical velocity jump (Delta u)(crit) exists, above which shear significantly broadens the entrainment interfacial layer (EIL), enhances cloud-top cooling, and increases the mean entrainment velocity; shear effects are negligible when the velocity jump is below (Delta u)(crit). Second, a depletion velocity jump (Delta u)(dep) exists, above which shear-enhanced mixing reduces cloud-top radiative cooling, thereby weakening the large convective motions; shear effects remain localized within the EIL when the velocity jump is below ((Delta)u)(dep). The critical velocity jump and depletion velocity jump are provided as a function of in-cloud and free-tropospheric conditions, and one finds (Delta u)(crit) similar or equal to 1-4 m s(-1) and (Delta u)(dep) similar or equal to 3-10 m s(-1) for typical subtropical conditions. Third, the individual contributions to the mean entrainment velocity from mixing, radiative cooling, and evaporative cooling strongly depend on the choice of the reference height where the entrainment velocity is calculated. This result implies that the individual contributions to the mean entrainment velocity should be estimated at a comparable height while deriving entrainment-rate parameterizations. Astrong shear alters substantially the magnitude and the height where these individual contributions reach their maxima, which further demonstrates the importance of shear on the dynamics of stratocumulus clouds. |
英文关键词 | Cloud forcing Mixing Wind Cloud radiative effects Cumulus clouds Numerical analysis modeling |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000443109700001 |
WOS关键词 | TOPPED BOUNDARY-LAYER ; LARGE-EDDY SIMULATION ; NOCTURNAL MARINE STRATOCUMULUS ; CLOUD-TOP ; MIXED LAYERS ; ENTRAINMENT INSTABILITY ; BUOYANCY REVERSAL ; MIXING LAYERS ; TURBULENCE ; CONVECTION |
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/29268 |
专题 | 地球科学 |
作者单位 | Max Planck Inst Meteorol, Hamburg, Germany |
推荐引用方式 GB/T 7714 | Schulz, Bernhard,Mellado, Juan Pedro. Wind Shear Effects on Radiatively and Evaporatively Driven Stratocumulus Tops[J]. JOURNAL OF THE ATMOSPHERIC SCIENCES,2018,75(9):3245-3263. |
APA | Schulz, Bernhard,&Mellado, Juan Pedro.(2018).Wind Shear Effects on Radiatively and Evaporatively Driven Stratocumulus Tops.JOURNAL OF THE ATMOSPHERIC SCIENCES,75(9),3245-3263. |
MLA | Schulz, Bernhard,et al."Wind Shear Effects on Radiatively and Evaporatively Driven Stratocumulus Tops".JOURNAL OF THE ATMOSPHERIC SCIENCES 75.9(2018):3245-3263. |
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