Diurnal evolution and structure of long-lived mesoscale convective vortices along the Mei-Yu Front over the East China Plains

The simulation uses lateral boundary conditions that vary only diurnally in time using analyses of recurring MCV events during 1-10 July 2007. Hence, the behavior of convection and vorticity follows a closely repeating diurnal cycle for each day during the simulation.

Assisted by the eastward extension of enhanced vorticity anomalies from the Sichuan basin, the incipient MCV forms in the morning hours over the immediate lee (east) of the central China mountain ranges (stage 1). From local afternoon to early evening, as the MCV moves over the plains, convection weakens in the daytime downward branch of the mountain-plains solenoid. This allows the upper-level and lower-level portions of the vortex to partially decouple, and for convection to shift to the east-southeast side of the surface vortex (stage 2).