A simulation of the merger of convective clouds in the torrential rainfalls associated with the Meiyu front

The merger of convective clouds in severe precipitation associated with the Meiyu front occurred near Nanjing during 4–5 July 2003 is investigated using satellite observational analyses and numerical simulations with the Weather Research and Forecast version 3.2. It is found that the merger of convective clouds plays a crucial role in the excessive storm. The severe rainfall event experiences a multi-scale organized process ranging from triggered convective bulbs, growing convective cells, to the formation of the convective complex. The development of convections causes the large-scale dynamic and thermodynamic environment change, which in turn favors the organized processes of convective systems and promotes multi-scale coupling of the nonlinear interaction between convections and its large-scale environment.