Numerical Simulation of the Structural Characteristics and Precipitation Mechanism of Stratiform Clouds with Embedded Convections

Stratiform clouds with embedded convections represent an important precipitation system in China.Precipitation from this system has characteristics of both convective and stratiform cloud.We studied this important process on May 29, 2012 using a mesoscale Weather Research and Forecasting (WRF) model and a three-dimension growth model.Since the resulting simulation of rainfall and radar echo were similar to observation results, we then analyzed the microphysical structural characteristics and precipitation mechanism of stratiform and convective clouds, respectively, in stratiform clouds with embedded convections.Results show that there is a “seeder-feeder” mechanism in this precipitation system, and this mechanism is simple in stratiform cloud.In convective cloud, however, because of the frequent circular particle movement between the upper and lower levels, this mechanism can occur in both the upper and lower cloud levels and so the particles can grow bigger.At low levels of the cloud system, the particles move into the embedded convective cloud, while at high levels, the particles fall from the convective cloud to the stratiform cloud.Stratiform clouds with embedded convections give full play to the advantages of convective and stratiform cloud, so their precipitation efficiency is high.