Effect of intense wind shear across the inversion on stratocumulus clouds

• Published in: Geophysical research letters Vol. 35; no. 15; pp. L15814 - n/a
• Main Authors: Wang, Shouping, Golaz, Jean-Christophe, Wang, Qing
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01-08-2008; Blackwell Publishing Ltd
• Subjects: Atmospheric Processes; Boundary layer processes; Clouds and cloud feedbacks; Earth sciences; Earth, ocean, space; Exact sciences and technology; stratocumulus clouds; Turbulence; turbulent mixing; wind shear; stratocumulus clouds; wind shear; turbulent mixing; models; inverse problem; Stratocumulus cloud; kinetic energy; Entrainment (atmosphere, ocean); strength; thickness; mixing; clouds; velocity; turbulence; Inversion layer; lead; intensity; Large eddy simulation; cooling; Turbulence energy; Height; equilibrium; reduction; Richardson number; Wind shear; Cloud top
• DOI: 10.1029/2008GL033865
• EISSN: 1944-8007
• ISSN: 0094-8276

A large‐eddy simulation model is used to examine the impact of the intense cross‐inversion wind shear on the stratocumulus cloud structure. The wind shear enhanced entrainment mixing effectively reduces the cloud water and thickens the inversion layer. It leads to a reduction of the turbulence kinetic energy (TKE) production in the cloud layer due to the weakened cloud‐top radiative cooling and the formation of a turbulent and cloud free sublayer within the inversion. The thickness of the sublayer increases with the enhanced wind shear intensity. Under the condition of a weaker inversion, the enhanced shear mixing within the inversion layer even lowers the cloud‐top height and reduces the entrainment velocity. Finally, increasing wind shear or reducing inversion strength tends to create an inversion layer with a constant bulk Richardson number (∼0.3), suggesting that an equilibrium value of the Richardson number is reached.