Simulation study of three-dimensional airflow structure of mesovortexes along Meiyu front

A simulation of the vortexes process along Meiyu front during the latter period of June 1999 was conducted using mesoscale model with a four-dimensional data assimilation. By using the model output of high temporal and spatial resolution, two different scale vortexes (a mesoscale α-vortex and a mesoscale β-vortex) during 28-30 June 1999 was analyzed: the three-dimensional airflow structure of vortexes were examined by drawing trajectories and tracing the thermodynamic properties of some representative particles. The results show: 1) Three branches of airflow constitute the airflow structure of mesoscale α-vortex: dry and cold eastern to northeastern airflow from low layer in northwestern region; wet and warm southwestern airflow from low and middle layers in southeastern region; west-northwestern airflow from high layer. 2) On lee side of Mufu Mountain, northwestern airflow south to the α-vortex and southwestern airflow converge, and a mesoscale β-vortex is formed. 3) The airflows that constitute mesoscale β-vortex are: southeastern and southwestern airflows from low layer; southwestern and west-southwestern airflows from middle and high layers.