A Cloud Top Radiative Cooling Model Coupled With CLUBB in the Community Atmosphere Model: Description and Simulation of Low Clouds. (15th April 2019)

• Record Type: Journal Article
• Authors: Guo, Zhun; Wang, Minghuai; Larson, Vincent E.; Zhou, Tianjun
• Is Part Of: Journal of advances in modeling earth systems. Volume 11:Number 4(2019)
• Page Start: 979
• Page End: 997
• Publication Date: 2019-04-15
• Subjects: low cloud -- buoyancy flux -- cloud top radiative cooling -- higher‐order closure scheme; Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1029/2018MS001505
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: In this study, a higher‐order closure scheme known as Cloud Layers Unified By Binormals (CLUBB) is coupled with a cloud top radiative cooling scheme (RAD). The cloud top radiative cooling scheme treats the buoyancy flux generated near the top of the boundary layer which helps the CLUBB scheme to better represent the radiation‐turbulence interaction on the condition of coarse vertical resolution. CLUBB with RAD is found to improve subtropical low‐cloud simulations, and the improvement is particularly evident for nocturnal stratocumulus. The improvements are caused by the stronger and more symmetric vertical turbulent mixing in the boundary layer, as CLUBB with RAD increases the variance of vertical velocity and vertical turbulent transports and reduces the skewness of vertical velocity by enhancing the radiative cooling effects and buoyancy fluxes at the cloud layer. The pumping effect related to the stronger vertical turbulent transports further cools and dries the lower boundary layer, which increases the local surface heating fluxes and further improves the low‐cloud simulations. Key Points: A cloud top radiative cooling model (RAD) is implemented in a higher‐order closure scheme CLUBB CLUBB with RAD improves subtropical low‐cloud simulations, especially for the nocturnal stratocumulus The improvements are related to the stronger and more symmetric vertical turbulent mixing