一次北方春季罕见暴雨天气的湿位涡分析

Analysis of Moist Potential Vorticity for an Inrequent Northern Rainstorm in Spring

应用湿位涡理论 ,对 2 0 0 3年 4月发生在山东境内的一次暴雨天气进行诊断。结果表明 :暴雨产生在θe 线陡立密集区附近 ,θe 线陡立密集区附近对流稳定度较小 ,有利于湿斜压涡度发展 ;湿位涡在 70 0hPa上具有MPV1 <0 ,MPV2 >0的特征 ,对流层高层高值湿位涡下传有利于位势不稳定能量的储存和释放 ,也是低涡东移发展为气旋的重要机制。

By using the theory of moist potential vorticity (MPV),a rainstorm happened in shandong province in April,2003 was analyzed.The results show that the rainstorm occurred in the neighbourhood of the stiff and dense section of the moist isentropes,where the convective degree of stability is so small that it is beneficial to the development of moist baroclinic vorticity. MPV 1<0and MPV 2>0 were characteristic of 700hPa.The downward spread of high from the upper troposphere availed the release and storage of potential instability energy.It is also an importmant mechaniam that the low vortex moved east and developed into cyclone.