the dynamical structure of the convective system at cl imax is studied and the air flow field is dep i cted . the ana i yses further show that north j i angsu and north annul is water vapor source of the rainstorm, and the inclining flow of wet air mass in pbl is the main water pass of convective systems 淮北、蘇北是魯南暴雨區(qū)對(duì)流層中下層氣流的源地,其充沛的水汽是此次過程前期水汽條件改善的重要原因,除水汽平流造成比濕增加外,對(duì)流層70ohpa及850hpa較強(qiáng)的上升運(yùn)動(dòng)也是該層次濕度增加的重要因素。