A Dynamic Study of One Kind of Meiyu Front Lows Producing Heavy Rainfall
梅雨锋上引发暴雨的低压动力学研究

Vorticity budget was diagnosed during the developing process of a cyclone which occurred on Meiyu (Baiu)front around the end of the second stage of Meiyu (Baiu) in 1998. It was found out that it is different not only from the classical Euramerican cyclone models, but also from the mesoscale lows which usually occur during Meiyu (Baiu) period. It belongs to another kind of cyclone on Meiyu (Baiu)front. Its characteristics are as follows: (1) Wind is the major feature of this cyclone. (2) From the results of the budgets of vorticity, two different factors influenced the development of the cyclone: one factor, the low\|level convergence field directly determined the occurrence and development of the cyclone. It created low\|level positive vorticity and had direct effects on the development of the cyclone; the other factor, the positive horizontal advection of vorticity in mid\|and upper troposphere and the whole\|level vertical advection of vorticity had indirect effects on the development of the cyclone through the low\|level convergence. (3) Based on a series of research work, including this paper, a physical model of one kind of cyclones on Meiyu front has been suggested.