中文摘要：

利用NCEP/NCAR 1°×1°再分析资料,计算了2009年第8号台风＂莫拉克＂引发浙江沿海地区强降水过程的湿位涡（MPV）和假相当位温（θse）,重点分析了正压项（MPV1）和斜压项（MPV2）的正负值变化特征。结果表明,通过判断大气对流不稳定处,θse陡立面密集区,能量锋较强区域,同时结合上升运动,可以作为判断强降水发生的判据。MPV1和MPV2与强降水有很好的对应关系。MPV1负值越小即其绝对值越大,降水强度越大,并且负值区分布变化与台风路径变化较为一致。MPV2的负值区出现,大气的斜压性增强,有利于降水增幅,同时此负值区影响范围及其所在高度层的变化也与降水增强与减弱有一定关系。当降水区完全由MPV2负值区所控制时,该区域降水即告结束。

英文摘要：

Based on the NCEP/NCAR 1°×1° reanalysis data,the calculation was made on moist potential vorticity and Pseudo-equivalent potential temperature of the heavy rain triggered by the 8th typhoon ＂Morakot＂ in the coastal areas of Zhejiang Province in 2009.The analysis was emphasized on variation characteristics of positive values and negative values of MPV1 and MPV2.As a result,it is the criterion to forecast severe precipitation by judging the instable place of atmospheric convective,dense section of abrupt slope,stronger section of energy front considering ascending motion.The center of negative MPV1 and MPV2 has a very good correspondence with the centre of rainstorm.The smaller the negative value of MPV1（e.g.the bigger the absolute value of MPV1） is,the heavier the precipitation is,and the distribution variation of negative value region of MPV1 is consistent with the variation of moving path of typhoon.Atmospheric baroclinity increases when negative MPV2 region arised,and it is benefit for the increasing of precipitation.At the same time the change of influence scope and height of the negative value section is relative with the increase or decrease of precipitation.When precipitation area is covered completely by negative MPV2 region,the precipitation in this area will end.