Large Eddy Simulation of Microphysics and Influencing Factors in Shallow Convective Clouds

• Main Authors: Zhuangzhuang Zhou, Chongzhi Yin, Chunsong Lu, Xingcan Jia, Fang Ye, Yujun Qiu, Muning Cheng
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Atmosphere
• Subjects: cloud microphysics; relative dispersion; large eddy simulation; shallow convective clouds
• Online Access: https://www.mdpi.com/2073-4433/12/4/485

A flight of shallow convective clouds during the SCMS95 (Small Cumulus Microphysics Study 1995) observation project is simulated by the large eddy simulation (LES) version of the Weather Research and Forecasting Model (WRF-LES) with spectral bin microphysics (SBM). This study focuses on relative dispersion of cloud droplet size distributions, since its influencing factors are still unclear. After validation of the simulation by aircraft observations, the factors affecting relative dispersion are analyzed. It is found that the relationships between relative dispersion and vertical velocity, and between relative dispersion and adiabatic fraction are both negative. Furthermore, the negative relationships are relatively weak near the cloud base, strengthen with the increasing height first and then weaken again, which is related to the interplays among activation, condensation and evaporation for different vertical velocity and entrainment conditions. The results will be helpful to improve parameterizations related to relative dispersion (e.g., autoconversion and effective radius) in large-scale models.